Scientific American Supplement, No. 460, October 25, 1884
by
Various
Part 1 out of 2
Produced by Don Kretz, Juliet Sutherland, Charles Franks and the DP Team
[Illustration]
SCIENTIFIC AMERICAN SUPPLEMENT NO. 460
NEW YORK, OCTOBER 25, 1884
Scientific American Supplement. Vol. XVIII, No. 460.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
* * * * *
TABLE OF CONTENTS.
I. CHEMISTRY. ETC.--Wolpert's Method of Estimating the
Amount of Carbonic Acid in the Air.--7 Figures.
Japanese Camphor.--Its preparation, experiments, and analysis
of the camphor oil.--By H. OISHI.
II. ENGINEERING AND MECHANICS.--Links in the History of the
Locomotive.--With two engravings of the Rocket.
The Flow of Water through Turbines and Screw Propellers.--By
ARTHUR RIGG.--Experimental researches.--Impact on level
plate.--Impact and reaction in confined channels.--4 figures.
Improved Textile Machinery.--The Textile Exhibition at
Islington.--5 figures.
Endless Rope Haulage.--2 figures.
III. TECHNOLOGY.--A Reliable Water Filter.--With engraving.
Simple Devices for Distilling Water.--4 figures.
Improved Fire Damp Detecter.--With full description and engraving.
Camera Attachment for Paper Photo Negatives.--2 figures.
Instantaneous Photo Shutter.--1 figure.
Sulphurous Acid.--Easy method of preparation for photographic
purposes.
IV. PHYSICS. ELECTRICITY, ETC.--Steps toward a Kinetic
Theory of Matter.--Address by Sir Wm. THOMSON at the Montreal
meeting of the British Association.
Application of Electricity to Tramways.--By M. HOLROYD
SMITH.--7 figures.
The Sunshine Recorder.--1 figure.
V. ARCHITECTURE AND ART.--The National Monument at Rome.--With
full page engraving.
On the Evolution of Forms of Art.--From a paper by Prof.
JACOBSTHAL.--Plant Forms the archetypes of cashmere
patterns.--Ornamental representations of plants of two
kinds.--Architectural forms of different ages.--20 figures.
VI. NATURAL HISTORY.--The Latest Knowledge about Gapes.--How
to keep poultry free from them.
The Voyage of the Vettor Pisani.--Shark fishing In the Gulf
of Panama.--Capture of Rhinodon typicus, the largest fish in
existence.
VII. HORTICULTURE, ETC.--The Proper Time for Cutting Timber.
Raising Ferns from Spores.--1 figure.
The Life History of Vaucheria.--Growth of alga vaucheria
under the microscope.--4 figures.
VIII. MISCELLANEOUS.--Fires in London and New York.
The Greely Arctic Expedition.--With engraving.
The Nile Expedition.--1 figure.
* * * * *
LINKS IN THE HISTORY OF THE LOCOMOTIVE.
It is, perhaps, more difficult to write accurate history than anything
else, and this is true not only of nations, kings, politicians, or wars,
but of events and things witnessed or called into existence in every-day
life. In _The Engineer_ for September 17, 1880, we did our best to place a
true statement of the facts concerning the Rocket before our readers. In
many respects this was the most remarkable steam engine ever built, and
about it there ought to be no difficulty, one would imagine, in arriving at
the truth. It was for a considerable period the cynosure of all eyes.
Engineers all over the world were interested in its performance. Drawings
were made of it; accounts were written of it, descriptions of it abounded.
Little more than half a century has elapsed since it startled the world by
its performance at Rainhill, and yet it is not too much to say that the
truth--the whole truth, that is to say--can never now be written. We are,
however, able to put some facts before our readers now which have never
before been published, which are sufficiently startling, and while
supplying a missing link in the history of the locomotive, go far to show
that much that has hitherto been held to be true is not true at all.
When the Liverpool and Manchester Railway was opened on the 15th of
September, 1830, among those present was James Nasmyth, subsequently the
inventor of the steam hammer. Mr. Nasmyth was a good freehand draughtsman,
and he sketched the Rocket as it stood on the line. The sketch is still in
existence. Mr. Nasmyth has placed this sketch at our disposal, thus earning
the gratitude of our readers, and we have reproduced as nearly as possible,
but to a somewhat enlarged scale, this invaluable link in the history of
the locomotive. Mr. Nasmyth writes concerning it, July 26, 1884: "This
slight and hasty sketch of the Rocket was made the day before the opening
of the Manchester and Liverpool Railway, September 12, 1830. I availed
myself of the opportunity of a short pause in the experimental runs with
the Rocket, of three or four miles between Liverpool and Rainhill, George
Stephenson acting as engine driver and his son Robert as stoker. The
limited time I had for making my sketch prevented me from making a more
elaborate one, but such as it is, all the important and characteristic
details are given; but the pencil lines, after the lapse of fifty-four
years, have become somewhat indistinct." The pencil drawing, more than
fifty years old, has become so faint that its reproduction has become a
difficult task. Enough remains, however, to show very clearly what manner
of engine this Rocket was. For the sake of comparison we reproduce an
engraving of the Rocket of 1829. A glance will show that an astonishing
transformation had taken place in the eleven months which had elapsed
between the Rainhill trials and the opening of the Liverpool and Manchester
Railway. We may indicate a few of the alterations. In 1829 the cylinders
were set at a steep angle; in 1830 they were nearly horizontal. In 1829 the
driving wheels were of wood; in 1830 they were of cast iron. In 1829 there
was no smoke-box proper, and a towering chimney; in 1830 there was a
smoke-box and a comparatively short chimney. In 1829 a cask and a truck
constituted the tender; in 1830 there was a neatly designed tender, not
very different in style from that still in use on the Great Western broad
gauge. All these things may perhaps be termed concomitants, or changes in
detail. But there is a radical difference yet to be considered. In 1829 the
fire-box was a kind of separate chamber tacked on to the back of the barrel
of the boiler, and communicating with it by three tubes; one on each side
united the water spaces, and one at the top the steam spaces. In 1830 all
this had disappeared, and we find in Mr. Nasmyth's sketch a regular
fire-box, such as is used to this moment. In one word, the Rocket of 1829
is different from the Rocket of 1830 in almost every conceivable respect;
and we are driven perforce to the conclusion that the Rocket of 1829
_never worked at all on the Liverpool and Manchester Railway; the engine of
1830 was an entirely new engine_. We see no possible way of escaping from
this conclusion. The most that can be said against it is that the engine
underwent many alterations. The alterations must, however, have been so
numerous that they were tantamount to the construction of a new engine. It
is difficult, indeed, to see what part of the old engine could exist in the
new one; some plates of the boiler shell might, perhaps, have been
retained, but we doubt it. It may, perhaps, disturb some hitherto well
rooted beliefs to say so, but it seems to us indisputable that the Rocket
of 1829 and 1830 were totally different engines.
[Illustration: FIG. 1. THE ROCKET, 1829. THE ROCKET, 1830.]
Our engraving, Fig. 1, is copied from a drawing made by Mr. Phipps,
M.I.C.E., who was employed by Messrs. Stephenson to compile a drawing of
the Rocket from such drawings and documents as could be found. This
gentleman had made the original drawings of the Rocket of 1829, under
Messrs. G. & R. Stephenson's direction. Mr. Phipps is quite silent about
the history of the engine during the eleven months between the Rainhill
trials and the opening of the railway. In this respect he is like every one
else. This period is a perfect blank. It is assumed that from Rainhill the
engine went back to Messrs. Stephenson's works; but there is nothing on the
subject in print, so far as we are aware. Mr. G.R. Stephenson lent us in
1880 a working model of the Rocket. An engraving of this will be found in
_The Engineer_ for September 17, 1880. The difference between it and the
engraving below, prepared from Mr. Phipps' drawing, is, it will be seen,
very small--one of proportions more than anything else. Mr. Stephenson says
of his model: "I can say that it is a very fair representation of what the
engine was before she was altered." Hitherto it has always been taken for
granted that the alteration consisted mainly in reducing the angle at which
the cylinders were set. The Nasmyth drawing alters the whole aspect of the
question, and we are now left to speculate as to what became of the
original Rocket. We are told that after "it" left the railway it was
employed by Lord Dundonald to supply steam to a rotary engine; then it
propelled a steamboat; next it drove small machinery in a shop in
Manchester; then it was employed in a brickyard; eventually it was
purchased as a curiosity by Mr. Thomson, of Kirkhouse, near Carlisle, who
sent it to Messrs. Stephenson to take care of. With them it remained for
years. Then Messrs. Stephenson put it into something like its original
shape, and it went to South Kensington Museum, where "it" is now. The
question is, What engine is this? Was it the Rocket of 1829 or the Rocket
of 1830, or neither? It could not be the last, as will be understood from
Mr. Nasmyth's drawing; if we bear in mind that the so-called fire-box on
the South Kensington engine is only a sham made of thin sheet iron without
water space, while the fire-box shown in Mr. Nasmyth's engine is an
integral part of the whole, which could not have been cut off. That is to
say, Messrs. Stephenson, in getting the engine put in order for the Patent
Office Museum, certainly did not cut off the fire-box shown in Mr.
Nasmyth's sketch, and replace it with the sham box now on the boiler. If
our readers will turn to our impression for the 30th of June, 1876, they
will find a very accurate engraving of the South Kensington engine, which
they can compare with Mr. Nasmyth's sketch, and not fail to perceive that
the differences are radical.
In "Wood on Railroads," second edition, 1832, page 377, we are told that
"after those experiments"--the Rainhill trials--"were concluded, the
Novelty underwent considerable alterations;" and on page 399, "Mr.
Stephenson had also improved the working of the Rocket engine, and by
applying the steam more powerfully in the chimney to increase the draught,
was enabled to raise a much greater quantity of steam than before." Nothing
is said as to where the new experiments took place, nor their precise date.
But it seems that the Meteor and the Arrow--Stephenson engines--were tried
at the same time; and this is really the only hint Wood gives as to what
was done to the Rocket between the 6th of October, 1829, and the 15th of
September, 1830.
There are men still alive who no doubt could clear up the question at
issue, and it is much to be hoped that they will do so. As the matter now
stands, it will be seen that we do not so much question that the Rocket in
South Kensington Museum is, in part perhaps, the original Rocket of
Rainhill celebrity, as that it ever ran in regular service on the Liverpool
and Manchester Railway. Yet, if not, then we may ask, what became of the
Rocket of 1830? It is not at all improbable that the first Rocket was cast
on one side, until it was bought by Lord Dundonald, and that its history is
set out with fair accuracy above. But the Rocket of the Manchester and
Liverpool Railway is hardly less worthy of attention than its immediate
predecessor, and concerning it information is needed. Any scrap of
information, however apparently trifling, that can be thrown on this
subject by our readers will be highly valued, and given an appropriate
place in our pages.--_The Engineer_.
* * * * *
The largest grain elevator in the world, says the _Nashville American_, is
that just constructed at Newport News under the auspices of the Chesapeake
& Ohio Railway Co. It is 90 ft. wide, 386 ft. long, and about 164 ft. high,
with engine and boiler rooms 40 x 100 ft. and 40 ft. high. In its
construction there were used about 3,000 piles, 100,000 ft. of white-oak
timber, 82,000 cu. ft. of stone, 800,000 brick, 6,000,000 ft. of pine and
spruce lumber, 4,500 kegs of nails, 6 large boilers, 2 large engines, 200
tons of machinery, 20 large hopper-scales, and 17,200 ft. of rubber belts,
from 8 to 48 in. wide and 50 to 1,700 ft. long; in addition, there were
8,000 elevator buckets, and other material. The storage capacity is
1,600,000 bushels, with a receiving capacity of 30,000, and a shipping
capacity of 20,000 bushels per hour.
* * * * *
THE FLOW OF WATER THROUGH TURBINES AND SCREW PROPELLERS.
[Footnote: Paper read before the British Association at Montreal.]
By Mr. ARTHUR RIGG, C.E.
Literature relating to turbines probably stands unrivaled among all that
concerns questions of hydraulic engineering, not so much in its voluminous
character as in the extent to which purely theoretical writers have ignored
facts, or practical writers have relied upon empirical rules rather than
upon any sound theory. In relation to this view, it may suffice to note
that theoretical deductions have frequently been based upon a
generalization that "streams of water must enter the buckets of a turbine
without shock, and leave them without velocity." Both these assumed
conditions are misleading, and it is now well known that in every good
turbine both are carefully disobeyed. So-called practical writers, as a
rule, fail to give much useful information, and their task seems rather in
praise of one description of turbine above another. But generally, it is of
no consequence whatever how a stream of water may be led through the
buckets of any form of turbine, so long as its velocity gradually becomes
reduced to the smallest amount that will carry it freely clear of the
machine.
The character of theoretical information imparted by some _Chicago Journal
of Commerce_, dated 20th February, 1884. There we are informed that "the
height of the fall is one of the most important considerations, as the same
stream of water will furnish five times the horse power at ten ft. that it
will at five ft. fall." By general consent twice two are four, but it has
been reserved for this imaginative writer to make the useful discovery that
sometimes twice two are ten. Not until after the translation of Captain
Morris' work on turbines by Mr. E. Morris in 1844, was attention in America
directed to the advantages which these motors possessed over the gravity
wheels then in use. A duty of 75 per cent. was then obtained, and a further
study of the subject by a most acute and practical engineer, Mr. Boyden,
led to various improvements upon Mr. Fauneyron's model, by which his
experiments indicated the high duty of 88 per cent. The most conspicuous
addition made by Mr. Boyden was the diffuser. The ingenious contrivance had
the effect of transforming part of whatever velocity remained in the stream
after passing out of a turbine into an atmospheric pressure, by which the
corresponding lost head became effective, and added about 3 per cent. to
the duty obtained. It may be worth noticing that, by an accidental
application of these principles to some inward flow turbines, there is
obtained most, if not all, of whatever advantage they are supposed to
possess, but oddly enough this genuine advantage is never mentioned by any
of the writers who are interested in their introduction or sale. The
well-known experiments of Mr. James B. Francis in 1857, and his elaborate
report, gave to hydraulic engineers a vast store of useful data, and since
that period much progress has been made in the construction of turbines,
and literature on the subject has become very complete.
In the limits of a short paper it is impossible to do justice to more than
one aspect of the considerations relating to turbines, and it is now
proposed to bring before the Mechanical Section of the British Association
some conclusions drawn from the behavior of jets of water discharged under
pressure, more particularly in the hope that, as water power is extremely
abundant in Canada, any remarks relating to the subject may not fail to
prove interesting.
Between the action of turbines and that of screw propellers exists an exact
parallelism, although in one case water imparts motion to the buckets of a
turbine, while in the other case blades of a screw give spiral movement to
a column of water driven aft from the vessel it propels forward. Turbines
have been driven sometimes by impact alone, sometimes by reaction above,
though generally by a combination of impact and reaction, and it is by the
last named system that the best results are now known to be obtained.
The ordinary paddles of a steamer impel a mass of water horizontally
backward by impact alone, but screw propellers use reaction somewhat
disguised, and only to a limited extent. The full use and advantages of
reaction for screw propellers were not generally known until after the
publication of papers by the present writer in the "Proceedings" of the
Institution of Naval Architects for 1867 and 1868, and more fully in the
"Transactions" of the Society of Engineers for 1868. Since that time, by
the author of these investigations then described, by the English
Admiralty, and by private firms, further experiments have been carried out,
some on a considerable scale, and all corroborative of the results
published in 1868. But nothing further has been done in utilizing these
discoveries until the recent exigencies of modern naval warfare have led
foreign nations to place a high value upon speed. Some makers of torpedo
boats have thus been induced to slacken the trammels of an older theory and
to apply a somewhat incomplete form of the author's reaction propeller for
gaining some portion of the notable performance of these hornets of the
deep. Just as in turbines a combination of impact and reaction produces the
maximum practical result, so in screw propellers does a corresponding gain
accompany the same construction.
[Illustration: FIG. 1.]
[Illustration: FIG. 2.]
_Turbines_.--While studying those effects produced by jets of water
impinging upon plain or concave surfaces corresponding to buckets of
turbines, it simplifies matters to separate these results due to impact
from others due to reaction. And it will be well at the outset to draw a
distinction between the nature of these two pressures, and to remind
ourselves of the laws which lie at the root and govern the whole question
under present consideration. Water obeys the laws of gravity, exactly like
every other body; and the velocity with which any quantity may be falling
is an expression of the full amount of work it contains. By a sufficiently
accurate practical rule this velocity is eight times the square root of the
head or vertical column measured in feet. Velocity per second = 8 sqrt
(head in feet), therefore, for a head of 100 ft. as an example, V = 8 sqrt
(100) = 80 ft. per second. The graphic method of showing velocities or
pressures has many advantages, and is used in all the following diagrams.
Beginning with purely theoretical considerations, we must first recollect
that there is no such thing as absolute motion. All movements are relative
to something else, and what we have to do with a stream of water in a
turbine is to reduce its velocity relatively to the earth, quite a
different thing to its velocity in relation to the turbine; for while the
one may be zero, the other may be anything we please. ABCD in Fig. 1
represents a parallelogram of velocities, wherein AC gives the direction of
a jet of water starting at A, and arriving at C at the end of one second or
any other division of time. At a scale of 1/40 in. to 1 ft., AC represents
80 ft., the fall due to 100 ft. head, or at a scale of 1 in. to 1 ft., AC
gives 2 ft., or the distance traveled by the same stream in 1/40 of a
second. The velocity AC may be resolved into two others, namely, AB and AD,
or BC, which are found to be 69.28 ft. and 40 ft. respectively, when the
angle BAC--generally called _x_ in treatises on turbines--is 30 deg. If,
however, AC is taken at 2 ft., then A B will be found = 20.78 in., and BC =
12 in. for a time of 1/40 or 0.025 of a second. Supposing now a flat plate,
BC = 12 in. wide move from DA to CB during 0.025 second, it will be readily
seen that a drop of water starting from A will have arrived at C in 0.025
second, having been flowing along the surface BC from B to C without either
friction or loss of velocity. If now, instead of a straight plate, BC, we
substitute one having a concave surface, such as BK in Fig. 2, it will be
found necessary to move it from A to L in 0.025 second, in order to allow a
stream to arrive at C, that is K, without, in transit, friction or loss of
velocity. This concave surface may represent one bucket of a turbine.
Supposing now a resistance to be applied to that it can only move from A to
B instead of to L. Then, as we have already resolved the velocity A C into
AB and BC, so far as the former (AB) is concerned, no alteration occurs
whether BK be straight or curved. But the other portion, BC, pressing
vertically against the concave surface, BK, becomes gradually diminished in
its velocity in relation to the earth, and produces and effect known as
"reaction." A combined operation of impact and reaction occurs by further
diminishing the distance which the bucket is allowed to travel, as, for
examples, to EF. Here the jet is impelled against the lower edge of the
bucket, B, and gives a pressure by its impact; then following the curve BK,
with a diminishing velocity, it is finally discharged at K, retaining only
sufficient movement to carry the water clear out of the machine. Thus far
we have considered the movement of jets and buckets along AB as straight
lines, but this can only occur, so far as buckets are concerned, when their
radius in infinite. In practice these latter movements are always curves of
more or less complicated form, which effect a considerable modification in
the forms of buckets, etc., but not in the general principles, and it is
the duty of the designer of any form of turbine to give this consideration
its due importance. Having thus cleared away any ambiguity from the terms
"impact," and "reaction," and shown how they can act independently or
together, we shall be able to follow the course and behavior of streams in
a turbine, and by treating their effects as arising from two separate
causes, we shall be able to regard the problem without that inevitable
confusion which arises when they are considered as acting conjointly.
Turbines, though driven by vast volumes of water, are in reality impelled
by countless isolated jets, or streams, all acting together, and a clear
understanding of the behavior of any one of these facilitates and concludes
a solution of the whole problem.
_Experimental researches_.--All experiments referred to in this paper were
made by jets of water under an actual vertical head of 45 ft., but as the
supply came through a considerable length of 1/2 in. bore lead piping, and
many bends, a large and constant loss occurred through friction and bends,
so that the actual working head was only known by measuring the velocity of
discharge. This was easily done by allowing all the water to flow into a
tank of known capacity. The stop cock had a clear circular passage through
it, and two different jets were used. One oblong measured 0.5 in. by 0.15
in., giving an area of 0.075 square inch. The other jet was circular, and
just so much larger than 1/4 in. to be 0.05 of a square inch area, and the
stream flowed with a velocity of 40 ft. per second, corresponding to a head
of 25 ft. Either nozzle could be attached to the same universal joint, and
directed at any desired inclination upon the horizontal surface of a
special well-adjusted compound weighing machine, or into various bent tubes
and other attachments, so that all pressures, whether vertical or
horizontal, could be accurately ascertained and reduced to the unit, which
was the quarter of an ounce. The vertical component _p_ of any pressure P
may be ascertained by the formula--
_p_ = P sin alpha,
where alpha is the angle made by a jet against a surface; and in order to
test the accuracy of the simple machinery employed for these researches,
the oblong jet which gave 71 unit when impinging vertically upon a circular
plate, was directed at 60 deg. and 45 deg. thereon, with results shown in
Table I., and these, it will be observed, are sufficiently close to theory
to warrant reliance being placed on data obtained from the simple weighing
machinery used in the experiment.
_Table I.--Impact on Level Plate._
--------------+--------------------+----------+----------+----------
| Inclination of jet | | |
Distance. | to the horizonal. | 90 deg. | 60 deg. | 45 deg.
--------------+--------------------+----------+----------+----------
| | Pressure | Pressure | Pressure
| | | |
/ | Experiment \ | / | 61.00 | 49.00
11/2 in. < | > | 71.00 < | |
\ | Theory / | \ | 61.48 | 50.10
| | | |
| | | |
/ | Experiment \ | / | 55.00 | 45.00
1 in. < | > | 63.00 < | |
\ | Theory / | \ | 54.00 | 45.00
| | | |
--------------+--------------------+----------+----------+----------
In each case the unit of pressure is 1/4 oz.
In the first trial there was a distance of 11/2 in. between the jet and point
of its contact with the plate, while in the second trial this space was
diminished to 1/2 in. It will be noticed that as this distance increases we
have augmented pressures, and these are not due, as might be supposed, to
increase of head, which is practically nothing, but they are due to the
recoil of a portion of the stream, which occurs increasingly as it becomes
more and more broken up. These alterations in pressure can only be
eliminated when care is taken to measure that only due to impact, without
at the same time adding the effect of an imperfect reaction. Any stream
that can run off at all points from a smooth surface gives the minimum of
pressure thereon, for then the least resistance is offered to the
destruction of the vertical element of its velocity, but this freedom
becomes lost when a stream is diverted into a confined channel. As pressure
is an indication and measure of lost velocity, we may then reasonably look
for greater pressure on the scale when a stream is confined after impact
than when it discharges freely in every direction. Experimentally this is
shown to be the case, for when the same oblong jet, discharged under the
same conditions, impinged vertically upon a smooth plate, and gave a
pressure of 71 units, gave 87 units when discharged into a confined
right-angled channel. This result emphasizes the necessity for confining
streams of water whenever it is desired to receive the greatest pressure by
arresting their velocity. Such streams will always endeavor to escape in
the directions of least resistance, and, therefore, in a turbine means
should be provided to prevent any lateral deviation of the streams while
passing through their buckets. So with screw propellers the great mass of
surrounding water may be regarded as acting like a channel with elastic
sides, which permits the area enlarging as the velocity of a current
passing diminishes. The experiments thus far described have been made with
jets of an oblong shape, and they give results differing in some degree
from those obtained with circular jets. Yet as the general conclusions from
both are found the same, it will avoid unnecessary prolixity by using the
data from experiments made with a circular jet of 0.05 square inch area,
discharging a stream at the rate of 40 ft. per second. This amounts to 52
lb. of water per minute with an available head of 25 ft., or 1,300
foot-pounds per minute. The tubes which received and directed the course of
this jet were generally of lead, having a perfectly smooth internal
surface, for it was found that with a rougher surface the flow of water is
retarded, and changes occur in the data obtained. Any stream having its
course changed presses against the body causing such change, this pressure
increasing in proportion to the angle through which the change is made, and
also according to the radius of a curve around which it flows. This fact
has long been known to hydraulic engineers, and formulae exist by which such
pressures can be determined; nevertheless, it will be useful to study these
relations from a somewhat different point of view than has been hitherto
adopted, more particularly as they bear upon the construction of screw
propellers and turbines; and by directing the stream, AB, Fig. 3,
vertically into a tube 3/8 in. internal diameter and bent so as to turn the
jet horizontally, and placing the whole arrangement upon a compound
weighing machine, it is easy to ascertain the downward pressure, AB, due to
impact, and the horizontal pressures, CB, due to reaction. In theoretical
investigations it may be convenient to assume both these pressures exactly
equal, and this has been done in the paper "On Screw Propellers" already
referred to; but this brings in an error of no importance so far as general
principles are involved, but one which destroys much of the value such
researches might, otherwise possess for those who are engaged in the
practical construction of screw propellers or turbines. The downward impact
pressure, AB, is always somewhat greater than the horizontal reaction, BC,
and any proportions between these two can only be accurately ascertained by
trials. In these particular experiments the jet of water flowed 40 ft. per
second through an orifice of 0.05 square inch area, and in every case its
course was bent to a right angle. The pressures for impact and reaction
were weighed coincidently, with results given by columns 1 and 2, Table II.
[Illustration: FIG. 3]
[Illustration: FIG. 4]
_Table II.--Impact and Reaction in Confined Channels._
-----------------------------+-------+---------+----------+-------
Number of column. | 1 | 2 | 3 | 4
-----------------------------+-------+---------+----------+-------
Description of experiments. |Impact.|Reaction.|Resultant.| Angles
| | | | ABS.
-----------------------------+-------+---------+----------+-------
Smooth London tube, 13/4 in. | 71 | 62 | 94.25 | 49 deg.
mean radius. | | | |
| | | |
Rough wrought iron tube, | 78 | 52 | 98.75 | 56.5 deg.
13/4 in. | | | |
| | | |
Smooth leaden tube bent to a | 71 | 40 | 81.5 | 60
sharp right angle. | | | |
-----------------------------+-------+---------+----------+------
The third column is obtained by constructing a parallelogram of forces,
where impact and reaction form the measures of opposing sides, and it
furnishes the resultant due to both forces. The fourth column gives the
inclination ABS, at which the line of impact must incline toward a plane
surface RS, Fig. 3, so as to produce this maximum resultant perpendicularly
upon it; as the resultant given in column 3 indicates the full practical
effect of impact and reaction. When a stream has its direction changed to
one at right angles to its original course, and as such a changed direction
is all that can be hoped for by ordinary screw propellers, the figures in
column 3 should bear some relationship to such cases. Therefore, it becomes
an inquiry of some interest as to what angle of impact has been found best
in those screw propellers which have given the best results in practical
work. Taking one of the most improved propellers made by the late Mr.
Robert Griffiths, its blades do not conform to the lines of a true screw,
but it is an oblique paddle, where the acting portions of its blades were
set at 48 deg. to the keel of the ship or 42 deg. to the plane of rotation.
Again, taking a screw tug boat on the river Thames, with blades of a
totally different form to those used by Mr. Griffiths, we still find them
set at the same angle, namely, 48 deg. to the keel or 42 deg. to the plane
of rotation. An examination of other screws tends only to confirm these
figures, and they justify the conclusion that the inclinations of blades
found out by practice ought to be arrived at, or at any rate approached, by
any sound and reliable theory; and that blades of whatever form must not
transgress far from this inclination if they are to develop any
considerable efficiency. Indeed, many favorable results obtained by
propellers are not due to their peculiarities, but only to the fact that
they have been made with an inclination of blade not far from 42 deg. to
the plan of rotation. Referring to column 4, and accepting the case of
water flowing through a smooth tube as analogous to that of a current
flowing within a large body of water, it appears that the inclination
necessary to give the highest resultant pressure is an angle of 49 deg.,
and this corresponds closely enough with the angle which practical
constructors of screw propellers have found to give the best results.
Until, therefore, we can deal with currents after they have been
discharged from the blades of a propeller, it seems unlikely that anything
can be done by alterations in the pitch of a propeller. So far as concerns
theory, the older turbines were restricted to such imperfect results of
impact and reaction as might be obtained by turning a stream at right
angles to its original course; and the more scientific of modern turbine
constructors may fairly claim credit for an innovation by which practice
gave better results than theory seemed to warrant; and the consideration of
this aspect of the question will form the concluding subject of the present
paper. Referring again to Fig. 3, when a current passes round such a curve
as the quadrant of a circle, its horizontal reaction appears as a pressure
along _c_ B, which is the result of the natural integration of all the
horizontal components of pressures, all of which act perpendicularly to
each element of the concave surface along which the current flows. If, now,
we add another quadrant of a circle to the curve, and so turn the stream
through two right angles, or 180 deg., as shown by Fig. 4, then such a
complete reversal of the original direction represents the carrying of it
back again to the highest point; it means the entire destruction of its
velocity, and it gives the maximum pressure obtainable from a jet of water
impinging upon a surface of any form whatsoever. The reaction noticed in
Fig. 3 as acting along _c_ B is now confronted by an impact of the now
horizontal stream as it is turned round the second 90 deg. of curvature,
and reacts also vertically downward. It would almost seem as if the first
reaction from B to F should be exactly neutralized by the second impact
from F to D. But such is not the case, as experiment shows an excess of the
second impact over the first reaction amounting to six units, and shows
also that the behavior of the stream through its second quadrant is
precisely similar in kind to the first, only less in degree. Also the
impact takes place vertically in one case and horizontally in the other.
The total downward pressure given by the stream when turned 180 deg. is
found by experiment thus: Total impact and reaction from 180 deg. change in
direction of current = 132 units; and by deducting the impact 71 units, as
previously measured, the new reaction corresponds with an increase of 61
units above the first impact. It also shows an increase of 37.75 units
above the greatest resultant obtained by the same stream turned through 90
deg. only. Therefore, in designing a screw propeller or turbine, it would
seem from these experiments desirable to aim at changing the direction of
the stream, so far as possible, into one at 180 deg. to its original
course, and it is by carrying out this view, so far as the necessities of
construction will permit, that the scientifically designed modern turbine
has attained to that prominence which it holds at present over all
hydraulic motors. Much more might be written to extend and amplify the
conclusions that can be drawn from the experiments described in the present
paper, and from many others made by the writer, but the exigencies of time
and your patience alike preclude further consideration of this interesting
and important subject.
* * * * *
IMPROVED TEXTILE MACHINERY.
[Illustration: THE TEXTILE EXHIBITION, ISLINGTON.]
In the recent textile exhibition at Islington, one of the most extensive
exhibits was that, of Messrs. James Farmer and Sons, of Salford. The
exhibit consists of a Universal calender, drying machines, patent creasing,
measuring, and marking machines, and apparatus for bleaching, washing,
chloring, scouring, soaping, dunging, and dyeing woven fabrics. The purpose
of the Universal calender is, says the _Engineer_, to enable limited
quantities of goods to be finished in various ways without requiring
different machines. The machine consists of suitable framing, to which is
attached all the requisite stave rails, batching apparatus, compound
levers, top and bottom adjusting screws, and level setting down gear, also
Stanley roller with all its adjustments. It is furthermore supplied with
chasing arrangement and four bowls; the bottom one is of cast iron, with
wrought iron center; the next is of paper or cotton; the third of chilled
iron fitted for heating by steam or gas, and the top of paper or cotton. By
this machine are given such finishes as are known as "chasing finish" when
the thready surface is wanted; "frictioning," or what is termed "glazing
finish," "swigging finish," and "embossing finish;" the later is done by
substituting a steel or copper engraved roller in place of the friction
bowl. This machine is also made to I produce the "Moire luster" finish. The
drying machine consists of nineteen cylinders, arranged with stave rails
and plaiting down apparatus. These cylinders are driven by bevel wheels, so
that each one is independent of its neighbor, and should any accident occur
to one or more of the cylinders or wheels, the remaining ones can be run
until a favorable opportunity arrives to repair the damage. A small
separate double cylinder diagonal engine is fitted to this machine, the
speed of which can be adjusted for any texture of cloth, and being of the
design it is, will start at once on steam being turned one. The machine
cylinders are rolled by a special machine for that purpose, and are
perfectly true on the face. Their insides are fitted with patent buckets,
which remove all the condensed water. In the machine exhibited, which is
designed for the bleaching, washing, chloring, and dyeing, the cloth is
supported by hollow metallic cylinders perforated with holes and corrugated
to allow the liquor used to pass freely through as much of the cloth as
possible; the open ends of the cylinders are so arranged that nearly all of
their area is open to the action of the pump. The liquor, which is drawn
through the cloth into the inside of the cylinders by the centrifugal
pumps, is discharged back into the cistern by a specially constructed
discharge pipe, so devised that the liquor, which is sent into it with
great force by the pump, is diverted so as to pour straight down in order
to prevent any eddies which could cause the cloth to wander from its
course. The cloth is supported to and from the cylinders by flat perforated
plates in such a manner that the force of the liquor cannot bag or displace
the threads of the cloth, and by this means also the liquor has a further
tendency to penetrate the fibers of the cloth. Means are provided for
readily and expeditiously cleansing the entire machine. The next machine
which we have to notice in this exhibit is Farmer's patent marking and
measuring machine, the purpose of which is to stamp on the cloths the
lengths of the same at regular distances. It is very desirable that drapers
should have some simple means of discovering at a glance what amount of
material they have in stock without the necessity of unrolling their cloth
to measure it, and this machine seems to perfectly meet the demands of the
case. The arrangement for effecting the printing and inking is shown in our
engraving at A. It is contained within a small disk, which can be moved at
will, so that it can be adapted to various widths of cloth or other
material. A measuring roller runs beside the printing disk, and on this is
stamped the required figures by a simple contrivance at the desired
distances, say every five yards. The types are linked together into a
roller chain which is carried by the disk, A, and they ink themselves
automatically from a flannel pad. The machine works in this way: The end of
the piece to be measured is brought down until it touches the surface of
the table, the marker is turned to zero, and also the finger of the dial on
the end of the measuring roller. The machine is then started, and the
lengths are printed at the required distances until it becomes necessary to
cut out the first piecing or joint in the fabric. The dial registers the
total length of the piece.
* * * * *
ENDLESS ROPE HAULAGE.
In the North of England Report, the endless rope systems are classified as
No. 1 and No 2 systems. No. 1, which has the rope under the tubs, is said
to be in operation in the Midland counties. To give motion to the rope a
single wheel is used, and friction for driving the rope is supplied either
by clip pulleys or by taking the rope over several wheels. The diagram
shows an arrangement for a tightening arrangement. One driving wheel is
used, says _The Colliery Guardian_, and the rope is kept constantly tight
by passing it round a pulley fixed upon a tram to which a heavy weight is
attached. Either one or two lines of rails are used. When a single line is
adopted the rope works backward and forward, only one part being on the
wagon way and the other running by the side of the way. When two lines are
used the ropes move always in one direction, the full tubs coming out on
one line and the empties going in on the other. The rope passes under the
tubs, and the connection is made by means of a clamp or by sockets in the
rope, to which the set is attached by a short chain. The rope runs at a
moderately high speed.
[Illustration: TIGHTENING ARRANGEMENT--ENDLESS ROPE HAULAGE.]
No. 2 system was peculiar to Wigan. A double line of rails is always used.
The rope rests upon the tubs, which are attached to the rope either singly
or in sets varying in number from two to twelve. The other engraving shows
a mode of connection between the tubs and the rope by a rope loop as shown.
[Illustration: ATTACHMENT TO ENDLESS ROPE "OVER."]
The tubs are placed at a regular distance apart, and the rope works slowly.
Motion is given to the rope by large driving pulleys, and friction is
obtained by taking the rope several times round the driving pulley.
* * * * *
A RELIABLE WATER FILTER.
Opinions are so firmly fixed at present that water is capable of carrying
the germs of disease that, in cases of epidemics, the recommendation is
made to drink natural mineral waters, or to boil ordinary water. This is a
wise measure, assuredly; but mineral waters are expensive, and, moreover,
many persons cannot get used to them. As for boiled water, that is a
beverage which has no longer a normal composition; a portion of its salts
has become precipitated, and its dissolved gases have been given off. In
spite of the aeration that it is afterward made to undergo, it preserves an
insipid taste, and I believe that it is not very digestible. I have
thought, then, that it would be important, from a hygienic standpoint, to
have a filter that should effectually rid water of all the microbes or
germs that it contains, while at the same time preserving the salts or
gases that it holds in solution. I have reached such a result, and,
although it is always delicate to speak of things that one has himself
done, I think the question is too important to allow me to hold back my
opinion in regard to the apparatus. It is a question of general hygiene
before which my own personality must disappear completely.
In Mr. Pasteur's laboratory, we filter the liquids in which microbes have
been cultivated, so as to separate them from the medium in which they
exist. For this purpose we employ a small unglazed porcelain tube that we
have had especially constructed therefor. The liquid traverses the porous
sides of this under the influence of atmospheric pressure, since we cause a
vacuum around the tube by means of an air-pump. We collect in this way,
after several hours, a few cubic inches of a liquid which is absolutely
pure, since animals may be inoculated with it without danger to them, while
the smallest quantity of the same liquid, when not filtered, infallibly
causes death.
This is the process that I have applied to the filtration of water. I have
introduced into it merely such modifications as are necessary to render the
apparatus entirely practical. My apparatus consists of an unglazed
porcelain tube inverted upon a ring of enameled porcelain, forming a part
thereof, and provided with an aperture for the outflow of the liquid. This
tube is placed within a metallic one, which is directly attached to a cock
that is soldered to the service pipe. A nut at the base that can be
maneuvered by hand permits, through the intermedium of a rubber washer
resting upon the enameled ring, of the tube being hermetically closed.
Under these circumstances, when the cock is turned on, the water fills the
space between the two tubes and slowly filters, under the influence of
pressure, through the sides of the porous one, and is freed from all solid
matter, including the microbes and germs, that it contains. It flows out
thoroughly purified, through the lower aperture, into a vessel placed there
to receive it.
I have directly ascertained that water thus filtered is deprived of all its
germs. For this purpose I have added some of it (with the necessary
precautions against introducing foreign organisms) to very changeable
liquids, such as veal broth, blood, and milk, and have found that there was
no alteration. Such water, then, is incapable of transmitting the germs of
disease.
[Illustration: CHAMBERLAND'S WATER FILTER.]
With an apparatus like the one here figured, and in which the filtering
tube is eight inches in length by about one inch in diameter, about four
and a half gallons of water per day may be obtained when the pressure is
two atmospheres--the mean pressure in Mr. Pasteur's laboratory, where my
experiments were made. Naturally, the discharge is greater or less
according to the pressure. A discharge of three and a half to four and a
half gallons of water seems to me to be sufficient for the needs of an
ordinary household. For schools, hospitals, barracks, etc., it is easy to
obtain the necessary volume of water by associating the tubes in series.
The discharge will be multiplied by the number of tubes.
In the country, or in towns that have no water mains, it will be easy to
devise an arrangement for giving the necessary pressure. An increase in the
porosity of the filtering tube is not to be thought of, as this would allow
very small germs to pass. This filter being a perfect one, we must expect
to see it soil quickly. Filters that do not get foul are just the ones that
do not filter. But with the arrangement that I have adopted the solid
matters deposit upon the external surface of the filter, while the inner
surface always remains perfectly clean. In order to clean the tube, it is
only necessary to take it out and wash it vigorously. As the tube is
entirely of porcelain, it may likewise be plunged into boiling water so as
to destroy the germs that may have entered the sides or, better yet, it may
be heated over a gas burner or in an ordinary oven. In this way all the
organic matter will be burned, and the tube will resume its former
porosity.--_M. Chamberland, La Nature._
* * * * *
SIMPLE DEVICES FOR DISTILLING WATER.
The alchemists dreamed and talked of that universal solvent which they so
long and vainly endeavored to discover; still, for all this, not only the
alchemist of old, but his more immediate successor, the chemist of to-day,
has found no solvent so universal as water. No liquid has nearly so wide a
range of dissolving powers, and, taking things all round, no liquid
exercises so slight an action upon the bodies dissolved--evaporate the
water away, and the dissolved substance is obtained in an unchanged
condition; at any rate, this is the general rule.
The function of water in nature is essentially that of a solvent or a
medium of circulation; it is not, in any sense, a food, yet without it no
food can be assimilated by an animal. Without water the solid materials of
the globe would be unable to come together so closely as to interchange
their elements; and unless the temperatures were sufficiently high to
establish an igneous fluidity, such as undoubtedly exists in the sun, there
would be no circulation of matter to speak of, and the earth would be, as
it were, locked up or dead.
When we look upon water as the nearest approach to a universal solvent that
even the astute scientist of to-day has been able to discover, who can
wonder that it is never found absolutely pure in nature? For wherever it
accumulates it dissolves something from its surroundings. Still, in a
rain-drop just formed we have very nearly pure water; but even this
contains dissolved air to the extent of about one-fiftieth of its volume,
and as the drop falls downward it takes up such impurities as may be
floating in the atmosphere; so that if our rain-drop is falling
immediately after a long drought, it becomes charged with nitrate or
nitrite of ammonia and various organic matters--perhaps also the spores or
germs of disease. Thus it will be seen that rain tends to wonderfully clear
or wash the atmosphere, and we all know how much a first rain is
appreciated as an air purifier, and how it carries down with it valuable
food for plants. The rain-water, in percolating through or over the land,
flows mainly toward the rivers, and in doing so it becomes more or less
charged with mineral matter, lime salts and common salt being the chief of
them; while some of that water which has penetrated more deeply into the
earth takes up far more solid matter than is ordinarily found in river
water. The bulk of this more or less impure water tends toward the ocean,
taking with it its load of salt and lime. Constant evaporation, of course,
takes place from the surface of the sea, so that the salt and lime
accumulate, this latter being, however, ultimately deposited as shells,
coral, and chalk, while nearly pure or naturally distilled water once more
condenses in the form of clouds. This process, by which a constant supply
of purified water is kept up in the natural economy, is imitated on a small
scale when water is converted into steam by the action of heat, and this
vapor is cooled so as to reproduce liquid water, the operation in question
being known as distillation.
For this purpose an apparatus known as a still is required; and although by
law one must pay an annual license fee for the right to use a still, it is
not usual for the government authorities to enforce the law when a still is
merely used for purifying water.
One of the best forms of still for the photographer to employ consists of a
tin can or bottle in which the water is boiled, and to this a tin tube is
adapted by means of a cork, one end of this tin tube terminating in a coil
passing through a tub or other vessel of cold water. A gas burner, as
shown, is a convenient source of heat, and in order to insure a complete
condensation of the vapor, the water in the cooling tub must be changed now
and again.
[Illustration]
Sometimes the vapor is condensed by being allowed to play against the
inside of a conical cover which is adapted to a saucepan, and is kept cool
by the external application of cold water; and in this case the still takes
the form represented by the subjoined diagrams; such compact and portable
stills being largely employed in Ireland for the private manufacture of
whisky.
[Illustration]
It is scarcely necessary to say that the condensed water trickles down on
the inside of the cone, and flows out at the spout.
An extemporized arrangement of a similar character may be made by passing a
tobacco pipe through the side of a tin saucepan as shown below, and
inverting the lid of the saucepan; if the lid is now kept cool by frequent
changes of water inside it, and the pipe is properly adjusted so as to
catch the drippings from the convex side of the lid, a considerable
quantity of distilled water may be collected in an hour or so.
The proportion of solid impurities present in water as ordinarily met with
is extremely variable: rain water which has been collected toward the end
of a storm contains only a minute fraction of a grain per gallon, while
river or spring water may contain from less than thirty grains per gallon
or so and upward. Ordinary sea water generally contains from three to four
per cent. of saline matter, but that of the Dead Sea contains nearly
one-fourth of its weight of salts.
[Illustration]
The three impurities of water which most interest the photographer are lime
or magnesia salts, which give the so-called hardness; chlorides (as, for
example, chloride of sodium or common salt), which throw down silver salts;
and organic matter, which may overturn the balance of photographic
operations by causing premature reduction of the sensitive silver
compounds. To test for them is easy. Hardness is easily recognizable by
washing one's hands in the water, the soap being curdled; but in many cases
one must rather seek for a hard water than avoid it, as the tendency of
gelatine plates to frill is far less in hard water than in soft water. It
is, indeed, a common and useful practice to harden the water used for
washing by adding half an ounce or an ounce of Epsom salts (sulphate of
magnesia) to each bucket of water. Chlorides--chloride of sodium or common
salt being that usually met with--may be detected by adding a drop or two
of nitrate of silver to half a wineglassful of the water, a few drops of
nitric acid being then added. A slight cloudiness indicates a trace of
chlorides, and a decided milkiness shows the presence of a larger quantity.
If it is wished to get a somewhat more definite idea of the amount, it is
easy to make up a series of standards for comparison, by dissolving known
weights of common salt in distilled or rain water, and testing samples of
them side by side with the water to be examined.
Organic matters may be detected by adding a little nitrate of silver to the
water, filtering off from any precipitate of chloride of silver, and
exposing the clear liquid to sunlight; a clean stoppered bottle being the
most convenient vessel to use. The extent to which a blackening takes place
may be regarded as approximately proportionate to the amount of organic
matter present.
Filtration on a small scale is not altogether a satisfactory mode of
purifying water, as organic impurities often accumulate in the filter, and
enter into active putrefaction when hot weather sets in.--_Photo. News._
* * * * *
IMPROVED FIRE-DAMP DETECTER.
According to the London _Mining Journal_, Mr. W.E. Garforth, of Normanton,
has introduced an ingenious invention, the object of which is to detect
fire-damp in collieries with the least possible degree of risk to those
engaged in the work. Mr. Garforth's invention, which is illustrated in the
diagram given below, consists in the use of a small India rubber hand ball,
without a valve of any description; but by the ordinary action of
compressing the ball, and then allowing it to expand, a sample of the
suspected atmosphere is drawn from the roof, or any part of the mine,
without the great risk which now attends the operation of testing for gas
should the gauze of the lamp be defective. The sample thus obtained is then
forced through a small protected tube on to the flame, when if gas is
present it is shown by the well-known blue cap and elongated flame. From
this description, and from the fact that the ball is so small that it can
be carried in the coat pocket, or, if necessary, in the waistcoat pocket,
it will be apparent what a valuable adjunct Mr. Garforth's invention will
prove to the safety-lamp. It has been supposed by some persons that
explosions have been caused by the fire-trier himself, but owing to his own
death in most cases the cause has remained undiscovered. This danger will
now be altogether avoided. It is well known that the favorite form of lamp
with the firemen is the Davy, because it shows more readily the presence of
small quantities of gas; but the Davy was some years ago condemned, and is
now strictly prohibited in all Belgian and many English mines. Recent
experience, gained by repeated experiments with costly apparatus, has
resulted in not only proving the Davy and some other descriptions of lamps
to be unsafe, but some of our Government Inspectors and our most
experienced mining engineers go so far as to say that "no lamp in a strong
current of explosive gas is safe unless protected by a tin shield."
[Illustration]
If such is the case, Mr. Garforth seems to have struck the key-note when,
in the recent paper read before the Midland Institute of Mining and Civil
Engineers, and which we have now before us, he says: "It would seem from
the foregoing remarks that in any existing safety-lamp where one
qualification is increased another is proportionately reduced; so it is
doubtful whether all the necessary requirements of sensitiveness,
resistance to strong currents, satisfactory light, self-extinction, perfect
combustion, etc., can ever be combined in one lamp."
The nearest approach to Mr. Garforth's invention which we have ever heard
of is that of a workman at a colliery in the north of England, who, more
than twenty years ago, to avoid the trouble of getting to the highest part
of the roof, used a kind of air pump, seven or eight feet long, to extract
the gas from the breaks; and some five years ago Mr. Jones, of Ebbw Vale,
had a similar idea. It appears that these appliances were so cumbersome,
besides requiring too great length or height for most mines, and
necessitating the use of both hands, that they did not come into general
use. The ideas, however, are totally different, and the causes which have
most likely led to the invention of the ball and protected tube were
probably never thought of until recently; indeed, Mr. Garforth writes that
he has only learned about them since his paper was read before the Midland
Institute, and some weeks after his patent was taken out.
No one, says Mr. Garforth, in his paper read before the Midland Institute,
will, I presume, deny that the Davy is more sensitive than the tin shield
lamp, inasmuch as in the former the surrounding atmosphere or explosive
mixture has only one thickness of gauze to pass through, and that on a
level with the flame; while the latter has a number of small holes and two
or three thicknesses of gauze (according to the construction of the lamp),
which the gas must penetrate before it reaches the flame. Moreover, the tin
shield lamp, when inclined to one side, is extinguished (though not so
easily as the Mueseler); and as the inlet holes are 6 inches from the top,
it does not show a thin stratum of fire-damp near the roof as perceptibly
as the Davy, which admits of being put in almost a horizontal position.
Although the Davy lamp was, nearly fifty years ago, pronounced unsafe, by
reason of its inability to resist an ordinary velocity of eight feet per
second, yet it is still kept in use on account of its sensitiveness. Its
advocates maintain that a mine can be kept safer by using the Davy, which
detects small quantities of gas, and thereby shows the real state of the
mine, than by a lamp which, though able to resist a greater velocity, is
not so sensitive, and consequently is apt to deceive. Assuming the Davy
lamp to be condemned (as it has already been in Belgium and in some English
mines), the Stephenson and some of the more recently invented lamps
pronounced unsafe, then if greater shielding is recommended the question
is, what means have we for detecting small quantities of fire-damp?
It would seem from the foregoing remarks that in any existing safety-lamp,
where one qualification is increased another is proportionately reduced; so
it is doubtful whether all the necessary requirements of sensitiveness,
resistance to strong currents, satisfactory light, self-extinction, perfect
combustion, etc., can ever be combined in one lamp. The object of the
present paper is to show that with the assistance of the fire-damp
detecter, the tin shield, or any other description of lamp, is made as
sensitive as the Davy, while its other advantages of resisting velocity,
etc., are not in any way interfered with. As a proof of this I may mention
that a deputy of experience recently visited a working place to make his
inspection. He reported the stall to be free from gas, but when the manager
and steward visited it with the detecter, which they applied to the roof
(where it would have been difficult to put even a small Davy), it drew a
sample of the atmosphere which, on being put to the test tube in the
tin-shield lamp, at once showed the presence of fire-damp. Out of
twenty-eight tests in a mine working a long-wall face the Davy showed gas
only eleven times, while the detecter showed it in every case. The
detecter, as will be perceived from the one exhibited, and the accompanying
sectional drawing, consists simply of an oval-shaped India rubber ball,
fitted with a mouthpiece. The diameter is about 21/4 inches by 3 inches, its
weight is two ounces, and it is so small that it can be carried without any
inconvenience in the coat or even in the waistcoat pocket. Its capacity is
such that all the air within it may be expelled by the compression of one
hand.
The mouthpiece is made to fit a tube in the bottom of the lamp, and when
pressed against the India rubber ring on the ball-flange, a perfectly tight
joint is made, which prevents the admission of any external air. The tube
in the bottom of the lamp is carried within a short distance of the height
of the wick-holder. It is covered at the upper end with gauze, besides
being fitted with other thicknesses of gauze at certain distances within
the tube; and if it be found desirable to further protect the flame against
strong currents of air, a small valve may be placed at the inlet, as shown
in the drawing. This valve is made of sufficient weight to resist the force
of a strong current, and is only lifted from its seat by the pressure of
the hand on the mouthpiece. It will be apparent from the small size and
elasticity of the detecter that the test can easily be made with one hand,
and when the ball is allowed to expand a vacuum is formed within it, and a
sample of the atmosphere drawn from the breaks, cavities, or highest parts
of the roof, or, of course, any portion of the mine. When the sample is
forced through the tube near the flame, gas if present at once reveals
itself by the elongation of the flame in the usual way, at the same time
giving an additional proof by burning with a blue flame on the top of the
test tube. If gas is not present, the distinction is easily seen by the
flame keeping the same size, but burning with somewhat greater brightness,
owing to the increased quality of oxygen forced upon it.
I venture to claim for this method of detecting fire-damp among other
advantages: 1. The detecter, on account of its size, can be placed in a
break in the roof where an ordinary lamp--even a small Davy--could not be
put, and a purer sample of the suspected atmosphere is obtained than would
be the case even a few inches below the level of the roof, 2. The obtaining
and testing of a sample in the manner above described takes away the
possibility of an explosion, which might be the result if a lamp with a
defective gauze were placed in an explosive atmosphere. No one knows how
many explosions have not been caused by the fire-trier himself. This will
now be avoided. (Although lamps fitted with a tin shield will be subjected
to the same strict examination as hitherto, still they do not admit of the
same frequent inspection as those without shields, for in the latter case
each workman can examine his own lamp as an extra precaution; whereas the
examination of the tin shield lamps will rest entirely with the lamp man.)
3. The lamp can be kept in a pure atmosphere while the sample is obtained
by the detecter, and at a greater height than the flame in a safety-lamp
could be properly distinguished. The test can afterward be made in a safe
place, at some distance from the explosive atmosphere; and, owing to the
vacuum formed, the ball (without closing the mouthpiece) has been carried a
mile or more without the gas escaping. 4. The detecter supplies a better
knowledge of the condition of the working places, especially in breaks and
cavities in the roof; which latter, with the help of a nozzle and staff,
may be reached to a height of ten feet or more, by the detecter being
pressed against the roof and sides, or by the use of a special form of
detecter. 5. Being able at will to force the contents of the detecter on to
the flame, the effects of an explosion inside the lamp need not be feared.
(This danger being removed, admits, I think, of the glass cylinder being
made of a larger diameter, whereby a better light is obtained; it may also
be considered quite as strong, when used with the detecter, as a lamp with
a small diameter, when the latter is placed in an explosive atmosphere.) 6.
The use of the detecter will permit the further protection of the present
tin shield lamp, by an extra thickness of gauze, if such addition is found
advantageous in resisting an increased velocity. 7. In the Mueseler,
Stephenson, and other lamps, where the flame is surrounded by glass, there
is no means of using the wire for shot firing. The detecter tube, although
protected by two thicknesses of gauze, admits of this being done by the use
of a special form of valve turned by the mouthpiece of the detecter. The
system of firing shots or using open lamps in the same pit where safety
lamps are used is exceedingly objectionable; still, under certain
conditions shots may be fired without danger. Whether safety lamps or
candles are used, it is thought the use of the detecter will afford such a
ready means of testing that more examinations will be made before firing a
shot, thereby insuring greater safety. 8. In testing for gas with a safety
lamp there is a fear of the light being extinguished, when the lamp is
suddenly placed in a quantity of gas, or in endeavoring to get a very
small light; this is especially the case with some kinds of lamps. With the
detecter this is avoided, as a large flame can be used, which is considered
by some a preferable means of testing for small quantities; and the test
can be made without risk. Where gas is present in large quantities, the
blue flame at the end of the test tube will be found a further proof. This
latter result is produced by the slightest compression of the ball. (I need
not point out the inconvenience and loss of time in having to travel a mile
or more to relight.) As regards the use of the detecter with open lights,
several of the foregoing advantages or modifications of them will apply.
Instead of having to use the safety lamp as at present, it is thought that
the working place will be more frequently examined, for a sample of the
suspected atmosphere can be carried to a safe place and forced on to the
naked light, when, if gas be present, it simply burns at the end of the
mouthpiece like an ordinary gas jet. There are other advantages, such as
examining the return airways without exposing the lamp, etc., which will be
apparent, and become of more or less importance according to the conditions
under which the tests are made.
In conclusion, I wish to paint out that the practice adopted at some
collieries, of having all the men supplied with the most approved lamp
(such as the Mueseler or tin shield lamp) is not a safe one. If the
strength of a chain is only equal to the weakest link, it may be argued
that the safety of a mine is only equal to that of the most careless man or
most unsafe lamp in it. If, therefore, the deputies, whose duty it is to
look for gas and travel the most dangerous parts of the mine, are obliged
to use the Davy on account of its sensitiveness, may it not be said that,
as their lamps are exposed equally with the workmen's to the high
velocities of air, they are the weak links in the safety of the mine? For
the reasons given, I venture to submit that the difficulties and dangers I
have mentioned will be largely reduced, if not wholly overcome, by the use
of the fire-damp detecter.
* * * * *
CAMERA ATTACHMENT FOR PAPER PHOTO NEGATIVES.
In computing the weight of the various items for a photographic tour, the
glass almost invariably comes out at the head of the list, and the farther
or longer the journey, so much more does the weight of the plates stand out
pre-eminent; indeed, if one goes out on a trip with only three dozen
half-plates, the glass will probably weigh nearly as much as camera, backs,
and tripod, in spite of the stipulation with the maker to supply plates on
"thin glass."
Next in importance to glass as a support comes paper, and it is quite easy
to understand that the tourist in out of the way parts might be able to
take an apparatus containing a roll of sensitive paper, when it would be
altogether impracticable for him to take an equivalent surface of coated
glass, and in such a case the roller slide becomes of especial value.
The roller slide of Melhuish is tolerably well known, and is, we believe,
now obtainable as an article of commerce. The slide is fitted up with two
rollers, _a a_, and the sensitive sheets, _b b_, are gummed together,
making one long band, the ends of which are gummed to pieces of paper
always kept on the rollers. The sensitive sheets are wound off the left or
reserve roller on to the right or exposed roller, until all are exposed.
[Illustration]
The rollers are supported on springs, _a a_, to render their motion
equal; they are turned by the milled heads, _m m_, and clamped when each
fresh sheet is brought into position by the nuts, _a squared a squared_. _c_, is a board
which is pressed forward by springs, _c c_, so as to hold the sheet to be
exposed, and keep it smooth against the plate of glass, _d_; when the sheet
has been exposed, the board is drawn back from the glass in order to
release the exposed sheet, and allow it to be rolled on the exposed roller;
the board is kept back while this is being done by turning the square rod,
_c squared_, half round, so that the angles of the square will not pass back
through the square opening until again turned opposite to it; _e e_ are
doors, by opening which the operator can see (through the yellow glass, _y
y_) to adjust the position of the sensitive sheets when changing them.
The remarkable similarity of such a slide to the automatic printing-frame
described last week will strike the reader; and, like the printing-frame,
it possesses the advantage of speed in working--no small consideration to
the photographer in a distant, and possibly hostile, country.
Fine paper well sized with an insoluble size and coated with a sensitive
emulsion is, we believe, the very best material to use in the roller slide;
and such a paper might be made in long lengths at a very low price, a
coating machine similar to that constructed for use in making carbon tissue
being employed. We have used such paper with success, and hope that some
manufacturer will introduce it into commerce before long. But the question
suggests itself, how are the paper negatives to be rendered transparent,
and how is the grain of the paper to be obliterated? Simply by pressure, as
extremely heavy rolling will render such paper almost as transparent as
glass, a fact abundantly demonstrated by Mr. Woodbury in his experiments on
the Photo-Filigrane process, and confirmed by some trials which we have
made.
It must be confessed that roller slide experiments which we have made with
sensitive films supported on gelatine sheets, or on such composite sheets
as the alternate rubber and collodion pellicle of Mr. Warnerke, have been
hardly satisfactory--possibly, however, from our own want of skill; while
no form of the Calotype process which we have tried has proved so
satisfactory as gelatino-bromide paper.--_Photo. News_.
* * * * *
INSTANTANEOUS PHOTO SHUTTER.
M. Audra, in the name of M. Braun, of Angouleme, has presented to the Photo
Society of France a new instantaneous shutter. The shutter is formed by a
revolving metallic disk out of which a segment has been taken. This disk is
placed in the center of the diaphragms, in order to obtain the greatest
rapidity combined with the least possible distance to travel. On the axis
to which this circular disk is fixed is a small wheel, to which is attached
a piece of string, and when the disk is turned round for the exposure the
string is wound round the wheel. If the string be pulled, naturally the
disk will revolve back to its former position so much the more quickly the
more violently the string is pulled. M. Braun has replaced the hand by a
steel spring attached to the drum of the lens (Fig. 2) By shortening or
lengthening the string, more or less rapid exposures may be obtained.
[Illustration: AAA, lens; B, aperture of lens; C, metallic disk; D,
wheel on the axis; E, cord or string; EEEE, knots in string; G, steel
spring; H, catch; K, socket for catch.]
* * * * *
SULPHUROUS ACID.--EASY METHOD OF PREPARATION FOR PHOTOGRAPHIC PURPOSES.
Within a short period sulphurous acid has become an important element in
the preparation of an excellent pyro developer for gelatine plates; and as
it is more or less unstable in its keeping qualities, some easy method of
preparing a small quantity which shall have a uniform strength is
desirable. A method recently described in the _Photographic News_ will
afford the amateur photographer a ready way of preparing a small quantity
of the acid.
[Illustration]
In the illustration given above, A and B are two bottles, both of which can
be closed tightly with corks. A hole is made in the cork in the bottle, A,
a little smaller than the glass tube which connects A and B. It is filed
out with a rat-tail file until it is large enough to admit the tube very
tightly. The tube may be bent easily, by being heated over a common
fish-tail gas burner or over the top of the chimney of a kerosene lamp, so
as to form two right angles, one end extending close to the bottom of the
bottle B as shown.
Having fitted up the apparatus, about two ounces of hyposulphite of soda
are placed in the bottle A, while the bottle B is about three-fourths
filled with water--distilled or melted ice water is to be preferred; some
sulphuric acid--about two ounces--is now diluted with about twice its bulk
of water, by first putting the water into a dish and pouring in the acid in
a steady stream, stirring meanwhile. It is well to set the dish in a sink,
to avoid any damage which might occur through the breaking of the dish by
the heat produced; when cool, the solution is ready for use and may be kept
in a bottle.
The cork which serves to adapt the bent tube to the bottle A is now just
removed for an instant, the other end remaining in the water in bottle B,
and about two or three ounces of the dilute acid are poured in upon the
hyposulphite, after which the cork is immediately replaced.
Sulphurous acid is now evolved by the action of the acid on the hypo, and
as the gas is generated it is led as a series of bubbles through the water
in the bottle B as shown. The air space above the water in bottle B soon
becomes filled by displacement with sulphurous acid gas, which is a little
over twice as heavy as air; so in order to expedite the complete saturation
of the water, it is convenient to remove the bottle A with its tube from
bottle B, and after having closed the latter by its cork or stopper, to
agitate it thoroughly by turning the bottle upside down. As the sulphurous
acid gas accumulated in the air space over the water is absorbed by the
water, a partial vacuum is created, and when the stopper is eased an inrush
of air may be noted. When, after passing fresh gas through the liquid for
some minutes, no further inrush of air is noted on easing the stopper as
before described after agitating the bottle, it may be concluded that the
water is thoroughly saturated with sulphurous acid and is strong enough for
immediate use. More gas can be generated by adding more dilute sulphuric
acid to the hypo until the latter is decomposed; then it should be thrown
aside, and a fresh charge put in the bottle. On preparing the solution it
is well to set the bottles on the outside ledge of the window, or in some
other open situation where no inconvenience will result from the escape of
the excess of sulphurous gas as it bubbles through the water.
The solution of sulphurous acid, if preserved at all, ought to be kept in
small bottles, completely filled and perfectly closed; but as it is very
easy to saturate a considerable quantity of water with sulphurous acid gas
in a short time, there is but little inducement to use a solution which may
possibly have become weakened by keeping.
Care should be taken not to add too much dilute acid to the hypo at a time,
else excessive effervescence will occur, and the solution will froth over
the top of the bottle.
* * * * *
THE NATIONAL MONUMENT AT ROME.
About three years ago the Italian Government invited the architects and
artists of the world to furnish competitive designs for a national monument
to be erected to the memory of King Victor Emanuel II. at Rome. More than
$1,800,000 were appropriated for the monument exclusive of the foundation.
It is very seldom that an artist has occasion to carry out as grand and
interesting a work as this was to be: the representation of the creator of
the Italian union in the new capitol of the new state surrounded by the
ruins and mementos of a proud and mighty past. Prizes of $10,000, $6,000,
and $4,000 were donated for the first, second, and third prize designs
respectively. Designs were entered, not only from Italy, but also from
Germany, France, Norway, Sweden, England, and America, and even from
Caucasus and Japan.
[Illustration: THE UNION OF ITALY. SACCONI'S PRIZE DESIGN FOR THE
NATIONAL MONUMENT, ROME, ITALY.]
The height and size of the monument were not determined on, nor was the
exact location, and the competitors had full liberty in relation to the
artistic character of the monument, and it was left for them to decide
whether it should be a triumphal arch, a column, a temple, a mausoleum, or
any other elaborate design. This great liberty given to the competitors was
of great value and service to the monument commission, as it enabled them
to decide readily what the character of the monument should be but it was a
dangerous point for the artists, at which most of them foundered. The
competition was resultless. Two prizes were given, but new designs had to
be called for, which were governed more or less by a certain programme
issued by the committee.
In place of the Piazza de Termini, a square extending from the church of
St. Maria degli Angeli to the new Via Nazionale, to which preference was
given by the competitors, the heights of Aracoeli were chosen. The monument
was to be erected at this historic place in front of the side wall of the
church, with the center toward the Corso, high above the surrounding
buildings. The programme called for an equestrian statue of the King
located in front of an architectural background which was to cover the old
church walls, and was to be reached by a grand staircase.
Even the result of this second competition was not definite, but as the
designers were guided by the programme, the results obtained were much more
satisfactory. The commission decided not to award the first prize, but
honored the Italian architects Giuseppi Sacconi and Manfredo Manfredi, and
the German Bruno Schmitz, with a prize of $2,000 each; and requested them
to enter into another competition and deliver their models within four
months, so as to enable the commission to come to a final decision. On June
18, the commission decided to accept Sacconi's design for execution, and
awarded a second prize of $2,000 to Manfredi.
Sacconi's design, shown opposite page, cut taken from the _Illustrirte
Zeitung_, needs but little explanation. An elegant gallery of sixteen
Corinthian columns on a high, prominent base is crowned by a high attica
and flanked by pavilions. It forms the architectural background for the
equestrian statue, and is reached by an elaborately ornamented staircase.
Manfredi's design shows a handsomely decorated wall in place of the
gallery, and in front of the wall an amphitheater is arranged, in the
center of which the equestrian statue is placed. Bruno Schmitz' design
shows a rich mosaic base supporting an Ionic portico, from the middle of
which a six column Corinthian "pronaos" projects, which no doubt would have
produced a magnificent effect in the streets of Rome.
* * * * *
ON THE EVOLUTION OF FORMS OF ORNAMENT.
[Footnote: From a paper by Prof. Jacobsthal in the _Transactions_ of the
Archaeological Society of Berlin.--_Nature_.]
The statement that modern culture can be understood only through a study of
all its stages of development is equally true of its several branches.
Let us assume that decorative art is one of these. It contains in itself,
like language and writing, elements of ancient and even of prehistoric
forms, but it must, like these other expressions of culture, which are
forever undergoing changes, adapt itself to the new demands which are made
upon it, not excepting the very arbitrary ones of fashion; and it is owing
to this cause that, sometimes even in the early stages of its development,
little or nothing of its original form is recognizable. Investigations the
object of which is to clear up this process of development as far as
possible are likely to be of some service; a person is more likely to
recognize the beauties in the details of ornamental works of art if he has
an acquaintance with the leading styles, and the artist who is freed from
the bondage of absolute tradition will be put into a better position to
discriminate between accidental and arbitrary and organic and legitimate
forms, and will thus have his work in the creation of new ones made more
easy for him.
Hence I venture to claim some measure of indulgence in communicating the
results of the following somewhat theoretical investigations, as they are
not altogether without a practical importance. I must ask the reader to
follow me into a modern drawing-room, not into one that will dazzle us with
its cold elegance, but into one whose comfort invites us to remain in it.
The simple stucco ceiling presents a central rosette, which passes over by
light conventional floral forms into the general pattern of the ceiling.
The frieze also, which is made of the same material, presents a similar but
somewhat more compact floral pattern as its chief motive. Neither of these,
though they belong to an old and never extinct species, has as yet attained
the dignity of a special name.
The walls are covered with a paper the ornamentation of which is based upon
the designs of the splendid textile fabrics of the middle ages, and
represents a floral pattern of spirals and climbing plants, and bears
evident traces of the influence of Eastern culture. It is called a
pomegranate or pine-apple pattern, although in this case neither
pomegranates nor pine-apples are recognizable.
Similarly with respect to the pattern of the coverings of the chairs and
sofas and of the stove-tiles; these, however, show the influence of Eastern
culture more distinctly.
The carpet also, which is not a true Oriental one, fails to rivet the
attention, but gives a quiet satisfaction to the eye, which, as it were,
casually glances over it, by its simple pattern, which is derived from
Persian-Indian archetypes (Cashmere pattern, Indian palmettas), and which
is ever rhythmically repeating itself (see Fig. 1).
[Illustration: FIG. 1.]
The floral pattern on the dressing-gown of the master of the house, as well
as on the light woolen shawl that is thrown round the shoulders of his
wife, and even the brightly colored glass knicknacks on the mantel-piece,
manufactured in Silesia after the Indian patterns of the Reuleaux
collection, again show the same motive; in the one case in the more
geometrical linear arrangement, in the other in the more freely entwined
spirals.
Now you will perhaps permit me to denominate these three groups of patterns
that occur in our new home fabrics as modern patterns. Whether we shall in
the next season be able, in the widest sense of the word, to call these
patterns modern naturally depends on the ruling fashion of the day, which
of course cannot be calculated upon (Fig. 2).
[Illustration: FIG. 2.]
I beg to be allowed to postpone the nearer definition of the forms that
occur in the three groups, which, however, on a closer examination all
present a good deal that they have in common. Taking them in a general way,
they all show a leaf-form inclosing an inflorescence in the form of an ear
or thistle; or at other times a fruit or a fruit-form. In the same way with
the stucco ornaments and the wall-paper pattern.
The Cashmere pattern also essentially consists of a leaf with its apex
laterally expanded; it closes an ear-shaped flower-stem, set with small
florets, which in exceptional cases protrude beyond the outline of the
leaf; the whole is treated rigorously as an absolute flat ornament, and
hence its recognition is rendered somewhat more difficult. The blank
expansion of the leaf is not quite unrelieved by ornament, but is set off
with small points, spots, and blossoms. This will be thought less strange
if we reflect on the Eastern representations of animals, in the portrayal
of which the flat expanses produced by the muscle-layers are often treated
from a purely decorative point of view, which strikes us as an exaggeration
of convention.
[Illustration: FIG. 3.]
One cannot go wrong in taking for granted that plant-forms were the
archetypes of all these patterns. Now we know that it holds good, as a
general principle in the history of civilization, that the tiller of the
ground supplants the shepherd, as the shepherd supplants the hunter; and
the like holds also in the history of the branch of art we are
discussing--representations of animals are the first to make their
appearance, and they are at this period remarkable for a wonderful
sharpness of characterization. At a later stage man first begins to exhibit
a preference for plant-forms as subjects for representation, and above all
for such as can in any way be useful or hurtful to him. We, however, meet
such plant-forms used in ornament in the oldest extant monuments of art in
Egypt, side by side with representations of animals; but the previous
history of this very developed culture is unknown. In such cases as afford
us an opportunity of studying more primitive though not equally ancient
stages of culture, as for instance among the Greeks, we find the above
dictum confirmed, at any rate in cases where we have to deal with the
representation of the indigenous flora as contradistinguished from such
representations of plants as were imported from foreign civilizations. In
the case that is now to occupy us, we have not to go back so very far in
the history of the world.
[Illustration: FIG. 4.]
The ornamental representations of plants are of two kinds. Where we have to
deal with a simple pictorial reproduction of plants as symbols (laurel
branches, boughs of olive and fir, and branches of ivy), _i. e._, with a
mere characteristic decoration of a technical structure, stress is laid
upon the most faithful reproduction of the object possible--the artist is
again and again referred to the study of Nature in order to imitate her.
Hence, as a general rule, there is less difficulty in the explanation of
these forms, because even the minute details of the natural object now and
then offer points that one can fasten upon. It is quite another thing when
we have to deal with actual decoration which does not aim at anything
further than at employing the structural laws of organisms in order to
organize the unwieldy substance, to endow the stone with a higher vitality.
These latter forms depart, even at the time when they originate, very
considerably from the natural objects. The successors of the originators
soon still further modify them by adapting them to particular purposes,
combining and fusing them with other forms so as to produce particular
individual forms which have each their own history (_e.g._, the acanthus
ornament, which, in its developed form, differs very greatly from the
acanthus plant itself); and in a wider sense we may here enumerate all such
forms as have been raised by art to the dignity of perfectly viable beings,
_e.g._, griffins, sphinxes, dragons, and angels.
[Illustration: Fig. 5.]
The deciphering and derivation of such forms as these is naturally
enough more difficult; in the case of most of them we are not even in
possession of the most necessary preliminaries to the investigation, and
in the case of others there are very important links missing (_e.g._,
for the well-known Greek palmettas). In proportion as the representation
of the plant was a secondary object, the travesty has been more and more
complete. As in the case of language, where the root is hardly
recognizable in the later word, so in decorative art the original form
is indistinguishable in the ornament. The migration of races and the
early commercial intercourse between distant lands have done much to
bring about the fusion of types; but again in contrast to this we find,
in the case of extensive tracts of country, notably in the Asiatic
continent, a fixity, throughout centuries, of forms that have once been
introduced, which occasions a confusion between ancient and modern works
of art, and renders investigations much more difficult. An old French
traveler writes: "J'ai vu dans le tresor d'Ispahan les vetements de
Tamerlan; ils ne different en rien de ceux d'aujourd'hui." Ethnology,
the natural sciences, and last, but not least, the history of technical
art are here set face to face with great problems.
[Illustration: FIG. 6.]
In the case in point, the study of the first group of artistic forms that
have been elaborated by Western art leads to definite results, because the
execution of the forms in stone can be followed on monuments that are
relatively not very old, that are dated, and of which the remains are still
extant. In order to follow the development, I ask your permission to go
back at once to the very oldest of the known forms. They come down to us
from the golden era of Greek decorative art--from the fourth or fifth
century B.C.--when the older simple styles of architecture were supplanted
by styles characterized by a greater richness of structure and more
developed ornament. A number of flowers from capitals in Priene, Miletus,
Eleusis, Athens (monument of Lysicrates), and Pergamon; also flowers from
the calathos of a Greek caryatid in the Villa Albani near Rome, upon many
Greek sepulchral wreaths, upon the magnificent gold helmet of a Grecian
warrior (in the Museum of St. Petersburg)--these show us the simplest type
of the pattern in question, a folded leaf, that has been bulged out,
inclosing a knob or a little blossom (see Figs. 3 and 4). This is an
example from the Temple of Apollo at Miletus, one that was constructed
about ten years ago, for educational purposes. Here is the specimen of the
flower of the monument to Lysicrates at Athens, of which the central part
consists of a small flower or fruits (Figs. 5 and 6).
[Illustration: FIG. 7.]
The form passes over into Roman art. The larger scale of the buildings,
and the pretensions to a greater richness in details, lead to a further
splitting up of the leaf into acanthus-like forms. Instead of a fruit-form
a fir-cone appears, or a pine-apple or other fruit in an almost
naturalistic form.
In a still larger scale we have the club-shaped knob developing into a
plant-stem branching off something after the fashion of a candelabrum, and
the lower part of the leaf, where it is folded together in a somewhat
bell-shaped fashion, becomes in the true sense of the word a campanulum,
out of which an absolute vessel-shaped form, as _e.g._ is to be seen in the
frieze of the Basilica Ulpia in Rome, becomes developed.
[Illustration: FIG. 8.]
Such remains of pictorial representation as are still extant present us
with an equally perfect series of developments. The splendid Graeco-Italian
vessels, the richly ornamented Apulian vases, show flowers in the spirals
of the ornaments, and even in the foreground of the pictorial
representations, which correspond exactly to the above mentioned Greek
relief representations. [The lecturer sent round, among other
illustrations, a small photograph of a celebrated vase in Naples
(representing the funeral rites of Patroclus), in which the flower in
question appears in the foreground, and is perhaps also employed as
ornament.] (Figs. 7 and 8.)
The Pompeian paintings and mosaics, and the Roman paintings, of which
unfortunately very few specimens have come down to us, show that the
further developments of this form were most manifold, and indeed they form
in conjunction with the Roman achievements in plastic art the highest point
that this form reached in its development, a point that the Renaissance,
which followed hard upon it, did not get beyond.
[Illustration: FIG. 9.]
Thus the work of Raphael from the loggias follows in unbroken succession
upon the forms from the Thermae of Titus. It is only afterward that a freer
handling of the traditional pattern arose, characterized by the
substitution of, for instance, maple or whitethorn for the acanthus-like
forms. Often even the central part falls away completely, or is replaced by
overlapping leaves. In the forms of this century we have the same process
repeated. Schinkel and Botticher began with the Greek form, and have put it
to various uses; Stuler, Strack, Gropius, and others followed in their wake
until the more close resemblance to the forms of the period of the
Renaissance in regard to Roman art which characterizes the present day was
attained (Fig. 9).
Now, what plant suggested this almost indispensable form of ornament, which
ranks along with the acanthus and palmetta, and which has also become so
important by a certain fusion with the structural laws of both?
[Illustration: FIG. 10.]
We meet with organism of the form in the family of the Araceae, or aroid
plants. An enveloping leaf (bract), called the spathe, which is often
brilliantly colored, surrounds the florets, or fruits, that are disposed
upon a spadix. Even the older writers--Theophrastus, Dioscorides, Galen,
and Pliny--devote a considerable amount of attention to several species of
this interesting family, especially to the value of their swollen stems as
a food-stuff, to their uses in medicine, etc. Some species of Arum were
eaten, and even nowadays the value of the swollen stems of some species of
the family causes them to be cultivated, as, for instance, in Egypt and
India, etc. (the so-called Portland sago, Portland Island arrowroot, is
prepared from the swollen stems of _Arum maculatum_). In contrast with the
smooth or softly undulating outlines of the spathe of Mediterranean Araceae,
one species stands out in relief, in which the sharply-marked fold of the
spathe almost corresponds to the forms of the ornaments which we are
discussing. It is _Dracunculus vulgaris_, and derives its name from its
stem, which is spotted like a snake. This plant, which is pretty widely
distributed in olive woods and in the river valleys of the countries
bordering on the Mediterranean, was employed to a considerable extent in
medicine by the ancients (and is so still nowadays, according to Von
Heldreich, in Greece). It was, besides, the object of particular regard,
because it was said not only to heal snake-bite, but the mere fact of
having it about one was supposed to keep away snakes, who were said
altogether to avoid the places where it grew. But, apart from this, the
striking appearance of this plant, which often grows to an enormous size,
would be sufficient to suggest its employment in art. According to
measurements of Dr. Julius Schmidt, who is not long since dead, and was the
director of the Observatory at Athens, a number of these plants grow in the
Valley of Cephisus, and attain a height of as much as two meters, the
spathe alone measuring nearly one meter. [The lecturer here exhibited a
drawing (natural size) of this species, drawn to the measurements above
referred to.]
[Illustration: FIG. 11.]
Dr. Sintenis, the botanist, who last year traveled through Asia Minor and
Greece, tells me that he saw beautiful specimens of the plant in many
places, _e.g._, in Assos, in the neighborhood of the Dardanelles, under the
cypresses of the Turkish cemeteries.
The inflorescence corresponds almost exactly to the ornament, but the
multipartite leaf has also had a particular influence upon its development
and upon that of several collateral forms which I cannot now discuss. The
shape of the leaf accounts for several as yet unexplained extraordinary
forms in the ancient plane-ornament, and in the Renaissance forms that have
been thence developed. It first suggested the idea to me of studying the
plant attentively after having had the opportunity five years ago of seeing
the leaves in the Botanic Gardens at Pisa. It was only afterward that I
succeeded in growing some flowers which fully confirmed the expectations
that I had of them (Figs. 10 and 11).
[Illustration: FIG. 12.]
The leaf in dracunculus has a very peculiar shape; it consists of a number
of lobes which are disposed upon a stalk which is more or less forked
(tends more or less to dichotomize). If you call to your minds some of the
Pompeian wall decorations, you will perceive that similar forms occur there
in all possible variations. Stems are regularly seen in decorations that
run perpendicularly, surrounded by leaves of this description. Before this,
these suggested the idea of a misunderstood (or very conventional)
perspective representation of a circular flower. Now the form also occurs
in this fashion, and thus negatives the idea of a perspective
representation of a closed flower. It is out of this form in combination
with the flower-form that the series of patterns was developed which we
have become acquainted with in Roman art, especially in the ornament of
Titus' Thermae and in the Renaissance period in Raphael's work. [The
lecturer here explained a series of illustrations of the ornaments referred
to (Figs. 12, 13, 14).]
The attempt to determine the course of the first group of forms has been to
a certain extent successful, but we meet greater difficulties in the study
of the second.
[Illustration: FIG. 13.]
It is difficult to obtain a firm basis on which to conduct our
investigations from the historical or geographical point of view into this
form of art, which was introduced into the West by Arabico-Moorish culture,
and which has since been further developed here. There is only one method
open to us in the determination of the form, which is to pass gradually
from the richly developed and strongly differentiated forms to the smaller
and simpler ones, even if these latter should have appeared
contemporaneously or even later than the former. Here we have again to
refer to the fact that has already been mentioned, to wit, that Oriental
art remained stationary throughout long periods of time. In point of fact,
the simpler forms are invariably characterized by a nearer and nearer
approach to the more ancient patterns and also to the natural flower-forms
of the Araceae. We find the spathe, again, sometimes drawn like an acanthus
leaf, more often, however, bulged out, coming to be more and more of a mere
outline figure, and becoming converted into a sort of background; then the
spadix, generally conical in shape, sometimes, however, altogether replaced
by a perfect thistle, at other times again by a pomegranate. Auberville, in
his magnificent work "L'Ornement des Tissus," is astonished to find the
term pomegranate-pattern almost confined to these forms, since their
central part is generally formed of a thistle-form. As far as I can
discover in the literature that is at my disposal, this question has not
had any particular attention devoted to it except in the large work upon
Ottoman architecture published in Constantinople under the patronage of
Edhem Pasha. The pomegranate that has served as the original of the pattern
in question is in this work surrounded with leaves till it gives some sort
of an approach to the pattern. (There are important suggestions in the book
as to the employment of melon-forms.) Whoever has picked the fruit from the
tender twigs of the pomegranate tree, which are close set with small
altered leaves, will never dream of attributing the derivation of the
thorny leaves that appear in the pattern to pomegranate leaves at any stage
of their development.
[Illustration: FIG. 14]
It does not require much penetration to see that the outline of the whole
form corresponds to the spathe of the Araceae, even although in later times
the jagged contour is all that has remained of it, and it appears to have
been provided with ornamental forms quite independently of the rest of the
pattern. The inner thistle-form cannot be derived from the common thistle,
because the surrounding leaves negative any such idea. The artichoke theory
also has not enough in its favor, although the artichoke, as well as the
thistle, was probably at a later time directly pressed into service. Prof.
Ascherson first called my attention to the extremely anciently cultivated
plant, the safflor (_Carthamus tinctoris_, Fig. 15), a thistle plant whose
flowers were employed by the ancients as a dye. Some drawings and dried
specimens, as well as the literature of the subject, first gave me a hope
to find that this plant was the archetype of this ornament, a hope that was
borne out by the study of the actual plant, although I was unable to grow
it to any great perfection.
In the days of the Egyptian King Sargo (according to Ascherson and
Schweinfurth) this plant was already well known as a plant of cultivation;
in a wild state it is not known (De Candolle, "Originel des Plantes
cultivees"). In Asia its cultivation stretches to Japan. Semper cites a
passage from an Indian drama to the effect that over the doorway there was
stretched an arch of ivory, and about it were bannerets on which wild
safran (_Saflor_) was painted.
[Illustration: FIG. 15]
The importance of the plant as a dye began steadily to decrease, and it has
now ceased to have any value as such in the face of the introduction of
newer coloring matters (a question that was treated of in a paper read a
short time ago by Dr. Reimann before this Society). Perhaps its only use
nowadays is in the preparation of rouge (_rouge vegetale_).
But at a time when dyeing, spinning, and weaving were, if not in the one
hand, yet at any rate intimately connected with one another in the narrow
circle of a home industry, the appearance of this beautiful gold-yellow
plant, heaped up in large masses, would be very likely to suggest its
immortalization in textile art, because the drawing is very faithful to
nature in regard to the thorny involucre. Drawings from nature of the plant
in the old botanical works of the sixteenth and seventeenth centuries look
very like ornamental patterns. Now after the general form had been
introduced, pomegranates or other fruits--for instance, pine-apples--were
introduced within the nest of leaves.
[Illustration: FIG. 16.]
Into the detailed study of the intricacies of this subject I cannot here
enter; the East-Asian influences are not to be neglected, which had
probably even in early times an effect upon the form that was assumed, and
have fused the correct style of compound flowers for flat ornament with the
above-mentioned forms, so as to produce peculiar patterns; we meet them
often in the so-called Persian textures and flat ornaments (Fig. 16).
We now come to the third group of forms--the so-called Cashmere pattern, or
Indian palmetta. The developed forms, which, when they have attained their
highest development, often show us outlines that are merely fanciful, and
represent quite a bouquet of flowers leaning over to one side, and
springing from a vessel (the whole corresponding to the Roman form with the
vessel), must be thrown to one side, while we follow up the simpler forms,
because in this case also we have no information as to either the where or
the when the forms originated. (Figs. 17, 18, 19.)
[Illustration: FIG. 17.]
Here again we are struck by resemblances to the forms that were the
subjects of our previous study, we even come across direct transitional
forms, which differ from the others only by the lateral curve of the apex
of the leaf; sometimes it is the central part, the spadix, that is bent
outward, and the very details show a striking agreement with the structure
of the aroid inflorescence, so much so that one might regard them as
actually copied from them.
[Illustration: FIG. 18.]
This form of ornament has been introduced into Europe since the French
expedition to Egypt, owing to the importation of genuine Cashmere shawls.
(When it cropped up in isolated forms, as in Venice in the fifteenth
century, it appears not to have exerted any influence; its introduction is
perhaps rather to be attributed to calico-printing.) Soon afterward the
European shawl-manufacture, which is still in a flourishing state, was
introduced. Falcot informs us that designs of a celebrated French artist,
Couder, for shawl-patterns, a subject that he studied in India itself, were
exported back to that country and used there (Fig. 20).
In these shawl-patterns the original simple form meets us in a highly
developed, magnificent, and splendidly colored differentiation and
elaboration. This we can have no scruples in ranking along with the
mediaeval plane-patterns, which we have referred to above, among the highest
achievements of decorative art.
[Illustration: FIG. 19.]
It is evident that it, at any rate in this high stage of development,
resisted fusion with Western forms of art. It is all the more incumbent
upon us to investigate the laws of its existence, in order to make it less
alien to us, or perhaps to assimilate it to ourselves by attaining to an
understanding of those laws. A great step has been made when criticism has,
by a more painstaking study, put itself into a position to characterize as
worthless ignorantly imitated, or even original, miscreations such as are
eternally cropping up. If we look at our modern manufactures immediately
after studying patterns which enchant us with their classical repose, or
after it such others as captivate the eye by their beautiful coloring, or
the elaborative working out of their details, we recognize that the
beautifully balanced form is often cut up, choked over with others, or
mangled (the flower springing up side down from the leaves), the whole
being traversed at random by spirals, which are utterly foreign to the
spirit of such a style, and all this at the caprice of uncultured, boorish
designers. Once we see that the original of the form was a plant, we shall
ever in the developed, artistic form cling, in a general way at least, to
the laws of its organization, and we shall at any rate be in a position to
avoid violent incongruities.
[Illustration: FIG. 20.]
I had resort, a few years ago, to the young botanist Ruhmer, assistant at
the Botanical Museum at Schoeneberg, who has unfortunately since died of
some chest-disease, in order to get some sort of a groundwork for direct
investigations. I asked him to look up the literature of the subject, with
respect to the employment of the Indian Araceae for domestic uses or in
medicine. A detailed work on the subject was produced, and establishes
that, quite irrespective of species of Alocasia and Colocasia that have
been referred to, a large number of Araceae were employed for all sorts of
domestic purposes. Scindapsus, which was used as a medicine, has actually
retained a Sanskrit name, "vustiva." I cannot here go further into the
details of this investigation, but must remark that even the incomplete and
imperfect drawings of these plants, which, owing to the difficulty of
preserving them, are so difficult to collect through travelers, exhibit
such a wealth of shape, that it is quite natural that Indian and Persian
flower-loving artists should be quite taken with them, and employ them
enthusiastically in decorative art. Let me also mention that Haeckel, in
his '"Letters of an Indian Traveler," very often bears witness to the
effect of the Araceae upon the general appearance of the vegetation, both in
the full and enormous development of species of Caladia and in the species
of Pothos which form such impenetrable mazes of interlooping stems.
In conclusion, allow me to remark that the results of my investigation, of
which but a succinct account has been given here, negative certain
derivations, which have been believed in, though they have never been
proved; such as that of the form I have last discussed from the Assyrian
palmetta, or from a cypress bent down by the wind. To say the least the
laws of formation here laid down have a more intimate connection with the
forms as they have come down to us, and give us a better handle for future
use and development. The object of the investigation was, in general words,
to prepare for an explanation of the questions raised; and even if the
results had turned out other than they have, it would have sufficed me to
have given an impulse to labors which will testify to the truth of the dead
master's words:
"Was Du ererbt von deinen Vaetern hast,
Erwirb es, um es zu besitzen."
* * * * *
STEPS TOWARD A KINETIC THEORY OF MATTER.
[Footnote: Meeting of the British Association, Montreal. 1884. Section A.
Mathematical and Physical science. Opening Address by Prof. Sir William
Thomson, M.A., LL.D., D.C.L., F.R.SS.L. and E., F.R.A.S., President of the
Section.]
By Sir WILLIAM THOMSON.
The now well known kinetic theory of gases is a step so important in the
way of explaining seemingly static properties of matter by motion, that it
is scarcely possible to help anticipating in idea the arrival at a complete
theory of matter, in which all its properties will be seen to be merely
attributes of motion. If we are to look for the origin of this idea we must
go back to Democritus, Epicurus, and Lucretius. We may then, I believe,
without missing a single step, skip 1800 years. Early last century we find
in Malebranche's "Recherche de la Verite," the statement that "la durete de
corps" depends on "petits tourbillons." [1] These words, embedded in a
hopeless mass of unintelligible statements of the physical, metaphysical,
and theological philosophies of the day, and unsupported by any
explanation, elucidation, or illustration throughout the rest of the three
volumes, and only marred by any other single sentence or word to be found
in the great book, still do express a distinct conception which forms a
most remarkable step toward the kinetic theory of matter. A little later we
have Daniel Bernoulli's promulgation of what we now accept as a surest
article of scientific faith--the kinetic theory of gases. He, so far as I
know, thought only of Boyle's and Mariotte's law of the "spring of air," as
Boyle called it, without reference to change of temperature or the
augmentation of its pressure if not allowed to expand for elevation of
temperature, a phenomenon which perhaps he scarcely knew, still less the
elevation of temperature produced by compression, and the lowering of
temperature by dilatation, and the consequent necessity of waiting for a
fraction of a second or a few seconds of time (with apparatus of ordinary
experimental magnitude), to see a subsidence from a larger change of
pressure down to the amount of change that verifies Boyle's law. The
consideration of these phenomena forty years ago by Joule, in connection
with Bernoulli's original conception, formed the foundation of the kinetic
theory of gases as we now have it. But what a splendid and useful building
has been placed on this foundation by Clausius and Maxwell, and what a
beautiful ornament we see on the top of it in the radiometer of Crookes,
securely attached to it by the happy discovery of Tait and Dewar,[2] that
the length of the free path of the residual molecules of air in a good
modern vacuum may amount to several inches! Clausius' and Maxwell's
explanations of the diffusion of gases, and of thermal conduction in gases,
their charmingly intelligible conclusion that in gases the diffusion of
heat is just a little more rapid than the diffusion of molecules, because
of the interchange of energy in collisions between molecules,[3] while the
chief transference of heat is by actual transport of the molecules
themselves, and Maxwell's explanation of the viscosity of gases, with the
absolute numerical relations which the work of those two great discoverers
found among the three properties of diffusion, thermal conduction, and
viscosity, have annexed to the domain of science a vast and ever growing
province.
[Footnote 1: "Preuve de la supposition que j'ay faite: Que la matiere
subtile ou etheree est necessairement composee de PETITS TOURBILLONS; et
qu'ils sont les causes naturelles de tous les changements qui arrivent a la
matiere; ce que je confirme par i'explication des effets les plus generaux
de la Physique, tels que sont la durete des corps, leur fluidite, leur
pesanteur, legerete, la lumiere et la refraction et reflexion de ses
rayons."--Malebranche, "Recherche de la Verite," 1712.]
[Footnote 2: Proc. R.S.E., March 2, 1874, and July 5, 1875.]
[Footnote 3: On the other hand, in liquids, on account of the crowdedness
of the molecules, the diffusion of heat must be chiefly by interchange of
energies between the molecules, and should be, as experiment proves it is,
enormously more rapid than the diffusion of the molecules themselves, and
this again ought to be much less rapid than either the material or thermal
diffusivities of gases. Thus the diffusivity of common salt through water
was found by Fick to be as small as 0.0000112 square centimeter per second;
nearly 200 times as great as this is the diffusivity of heat through water,
which was found by J.T. Bottomley to be about 0.002 square centimeter per
second. The material diffusivities of gases, according to Loschmidt's
experiments, range from 0.98 (the interdiffusivity of carbonic acid and
nitrous oxide) to 0.642 (the interdiffusivity of carbonic oxide and
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