Scientific American Suppl. No. 299
by
Various
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E-text prepared by Olaf Voss, Don Kretz, Juliet Sutherland, and the Online
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SCIENTIFIC AMERICAN SUPPLEMENT NO. 299
NEW YORK, SEPTEMBER 24, 1881
Scientific American Supplement. Vol. XII, No. 299.
Scientific American established 1845
Scientific American Supplement, $5 a year.
Scientific American and Supplement, $7 a year.
[Illustration]
* * * * *
TABLE OF CONTENTS.
I. ENGINEERING AND MECHANICS.--On the Progress and development
of the Marine Engine.--Marine engines.--The marine
boiler.--Steel boilers.--Corrosion of boilers.--How the marine
engine may be improved.--Consumption of fuel.--Evaporative
efficiency of marine locomotive boilers.--Screw propellers
Steam Ferry Boats of the Port of Marseilles.--2 figures.--
Transverse and longitudinal sections
Opening of a New English Dock. 1 figure
Improved Grain Elevator. 1 figure
Improved Dredger. 1 figure.--Single bucket dipper dredger
Railway Alarm Whistle
Furnace for the Manufacture of Sulphide of Carbon. 1 figure
Brouardel's Dry Inscribing Manometer. 1 figure.--Gas indication
of manometer
Centrifugal Apparatus for Casting Metals. 4 figures.--Centrifugal
metal moulding apparatus
Apparatus for the Manufacture of Wood Pulp. 2 figures.--Dresel's
wood pulp apparatus
Recent Progress of Industrial Science.--Presidential address,
Convention of Mechanical Engineers
The Hoboken Drainage Problem
II. TECHNOLOGY AND CHEMISTRY--On some Recent Improvements
in Lead Processes. By NORMAN C. COOKSON
Apparatus Used in Berlin for the Preparation of Gelatine Plates.--
I. Mixing apparatus.--II. Digestive apparatus.--III. Triturating
apparatus--IV. Washing apparatus--3 figures
How To Make Emulsions In Hot Weather. By A. L. HENDERSON
The Distillation and Rectification of Alcohols by the Rational
Use of Low Temperatures. By RAOUL PICTET.--1 figure.--Pictet's
apparatus for the rectification of alcohol by cold
The Removal of Noxious Vapors from Roasting Furnace Gases
New Gas Exhauster. 1 figure
Advance in the Price of Glycerine
Analysis of Oils or Mixtures of Oils Used for Lubricating Purposes
Nitrate of Amyl
III. ELECTRICITY, ETC.--The Electric Light in Earnock Colliery
Lightning and Telephone Wires
Conditions of Flames Under the Influence of Electricity
The Electric Stop-Motion in the Cotton Mill
Electrolytic Determinations and Separations. By ALEX, and M.
A. VON REIS.--Determination of cobalt.--Nickel--Iron.--Zinc.--
Manganese.--Bismuth.--Lead.--Copper.--Cadmium.--Tin.--Antimony.--
Arsenic.--Separation of iron from manganese.--Iron from Aluminum
IV. MEDICINE, SURGERY, ETC.--Treatment of Acute Rheumatism.
By ALFRED M. STILLE, M.D.
Method in Madness
Simple Methods to Staunch Accidental Hemorrhage. By EDWARD
BORCK, M.D.--Bleeding from upper arm.--From arteries in the
upper third of the arm.--From the thigh.--From the foot
Hot Water Compresses in Tetanus and Trismus
V. AGRICULTURE, ETC.--The Cultivation of Pyrethrum and Manufacture
of Powder
Trials of String Sheaf Binders at Derby, England
The Culture of Strawberries.--Garden culture.--Field culture
Some Hardy Flowers for Midsummer
The Time Consuming Match
VI. ARCHITECTURE, ART, ETC.--Suggestions in Decorative Art.
1 figure.--Silver ewer by Odiot, Paris
Artists' Homes. No. l4.--Bent's Brook, Holmwood, Surrey, Eng.--
6 figures.--Perspective, elevations, and plans
VII. OBITUARY.--Achille Delesse, eminent as geologist and mineralogist
* * * * *
ACHILLE DELESSE.
The death of this distinguished man must be recorded. An interesting
_resume_ of his labors by M. Daubree has appeared, from which we take
the following facts. After a training in his native town at the Lyceum
of Metz, which furnished so many scholars to the Polytechnic school,
Delesse was admitted at the age of twenty to this school. In 1839 he
left to enter the Corps des Mines. From the beginning of his career the
student engineer applied himself with ardor to the sciences to which
he was to devote his entire existence. The journeys which he undertook
then, and continued later, in France, Germany, Poland, England, and
Ireland, helped to confirm and develop the bent of his mind. He soon
arrived at important scientific results, and was rewarded, in 1845, by
having conferred to him by the university the course of mineralogy and
geology in the Faculty at Besancon, where Delesse at the same time
fulfilled the duties of engineer of mines. Five years later he returned
to Paris, where he continued his university duties, at first as deputy
of the course of geology at the Sorbonne, then as master of the
conferences at the Superior Normal School. Besides this, he continued
his profession of engineer of mines as inspector of the roads of Paris.
The first original researches of the young _savant_ concern pure
mineralogy; he studied a certain number of species, of which the
chemical nature was yet uncertain or altogether unknown, and his name
was appended to one of the species which he defined. He studied
also, and with success, the interesting modifications called
pseudomorphism--the mode of association of minerals, as well as their
magnetic properties. The attributes of a practical mineralogist aided
him greatly in the culture of a branch of geology to which Delesse has
rendered eminent services, in the recognition of rocks of igneous origin
and of others allied to them. He studied in the field, as well as by
investigations in the laboratory, for fifteen years, with an intelligent
and indefatigable perseverance, and, aided by the results of hundreds of
analyses, eruptive masses of the most varied kind, the knowledge derived
from which threw light upon the principles of science, from granites
and syenites to melaphyres and basalts. After thirty years of study
and progress, other _savants_, without differing from him, progressed
further in the intimate knowledge of rocks; but the historian of
science will not forget that Delesse was the precursor of this order
of research. His studies of metamorphism will long do him honor. The
mineralogical modifications which the eruptive rocks have undergone in
the mass are the permanent witnesses which attracted all his attention.
The chemical comparison of the metamorphic with the normal rock pointed
out distinctly the nature of the substances acquired or lost. One of the
principal results of these analyses has been to lessen the importance
attributed until then to heat alone, and to show in more than one case
the intervention of thermal sources and of other emanations from below,
to which the eruptive rocks have simply opened up tracks.
It is not only upon subjects relating to the history of rocks that
Delesse has touched. Witness his work on the infiltration of water, as
well as his volume relating to the materials of construction, published
on the occasion of the Exhibition of 1855. The nature of the deposits
which operate continually at the bottom of the sea offers points of
interest which well repay the labor of the geologist. He finds there,
indeed, a precious field to be compared with stratified deposits; for
in spite of the enormous depth to which they form a part of continents,
they are of analogous origin. Delesse laboriously studied the products
of the innumerable soundings taken in most of the seas. He arranged the
results in a work which has become classical with the beautiful atlas of
submarine drawings which accompany it. Though he never slackened in his
own especial work, he made much of the work of others. The "Revue des
Progres de la Geologie," with which he enriched the "Annales des Mines"
for twenty years, would have been sufficient to engross the time of a
less active scientific man, and one less ready to grasp the opening of a
discovery. This indefatigable theorist never neglected the applications
of science: the nature and the changes of the layers which form the
under earth; the course and the depth of the subterraneous sheets of
water; the mineralogical composition of the earth's vegetation, were
represented by him on several charts and plans drawn out in proper form.
His maps which follow the route of many of the great French lines of
railway explain the kind of soil upon which they are laid, and are of
daily use. In the pursuit of his numerous scientific works, Delesse
never failed in discharging his duties in the Corps des Mines. Having
in 1864 quitted the service of the Government of Paris, which he had
occupied for eighteen years, he was made professor of agriculture, of
drainage, and irrigation, at the School of Mines, where he established
instruction in these before being called to found the course of geology
at the Agricultural Institution. Promoted to be Inspector-General of
Mines in 1878, and charged with the division of the south east of
France, he preserved to the end of his life these new duties, for which,
to the regret of the School of Mines, he gave up his excellent lessons
there. During the year of 1870 Delesse fulfilled his duties as a
citizen, as engineer in preparation of cartridges in the department.
His nomination to the Academy of Sciences, which took place on the 6th
of January, 1879, satisfied the ambition of his life. He was for two
years President of the Central Commission of the Geographical Society;
he was also President of the Geological Society. He was not long to
enjoy the noble position acquired by his intelligence and his work.
He suffered from a serious malady, which, however, did not weaken his
intellect, and he continued from his bed of suffering to prepare the
reports for the Council-General of Mines, and that which recently he
addressed to the Academy on the occasion of his election. The greatness
and the rectitude of mind of Delesse, his astounding power of work, his
profound knowledge of science, his sympathetic sweetness, which were
associated with sterling modesty and loyalty of character, made him
esteemed and cherished throughout his whole career. He died on the 24th
of March.--_The Engineer._
* * * * *
[Illustration: SUGGESTIONS IN DECOTATIVE ART.--SILVER EWER, BY ODIOT,
PARIS.
(From The Workshop)]
* * * * *
THE ELECTRIC LIGHT AT EARNOCK COLLIERY.
On the afternoon of August 9, Earnock Colliery, near Hamilton, belonging
to Mr. John Watson, of Earnock, was the scene of an interesting
ceremonial which may well be said to mark a new era in mining annals.
In proceeding to win the rich mineral wealth of his estate, Mr. Watson
determined that, in respect of fittings, machinery, and general
appointments, it should be a model, and he has been highly successful
in giving practical effect to his aims. Among other things, he early
resolved to, if at all practicable, substitute the electric light for
the ordinary mode of illuminating the workings, and after investigating
the various systems, he decided on giving that of Mr. Swan a trial.
Accordingly, since April last, Messrs. D. & E. Graham, electrical
engineers, Glasgow, have been engaged fitting up the Swan incandescent
lamp, with modifications, to adapt it for safe use in the mine, and on
Tuesday the inauguration of the new light took place in presence of a
large company of leading gentlemen from Glasgow, Hamilton, and the West.
Arrived at the colliery about half-past one o'clock, the visitors were
received by Mr. Watson, and after a brief space spent in inspecting
the three magnificent winding and fan engines, the Guibal fan, and the
framework for screening the coal, they were conducted by Mr. James
Gilchrist, manager, down into the workings in the ell seam at a depth
of 118 fathoms. Here at the pit bottom, in the roads and at the face,
twenty-one Swan lamps were burning, giving forth a brilliant, steady
flame, the luminosity of which, while sufficient to supply the desired
light, had none of the disagreeable intensity associated with most
systems of electric lighting. Besides the pear-shaped Swan lamp, in
which the glowing or incandescence is carried on _in vacuo_, there is an
outer lantern, the invention of Mr. David Graham, consisting of a strong
glass globe, air-tight, protected with steel guards. Each lamp was also
connected with two different forms of Graham's patent safety air tight
contacts and switches for cutting off and letting on the current, the
effect of which, it is believed, would be to render the lamps quite
safe, even in the presence of explosive gas. At first the intention
was to employ the fan-engine to drive the dynamo-electric machine or
generator, but this was departed from, and an engine of 12 horse-power
was erected in the workshops on the surface for the purpose. From the
generator the electric cables, two in number, are conducted along the
roof of the workshops over ordinary telegraph poles to the pit-head at
No. 2 shaft, and thence down into the workings. From the ridge of the
workshops to the pithead, a distance of several hundred yards, the
cables consist of ordinary copper wire, three-eighths of an inch in
diameter; inside the workshop and below ground, to allow of their safe
handling, they are composed of insulated wires, while on the way down
the shaft they are inclosed in a galvanized tube. Near the bottom of the
shaft, branches are taken off to supply light to the principal roadways
and to the haulage engine-room, the main cables being carried into one
of the sections of the mine a distance of half-a-mile. After a careful
inspection of the lamps at the pit bottom, the party were photographed
in three groups, with the aid of the electric light, by Mr. Annan, of
Glasgow, who may well be credited with the distinction of being the
first to exercise his skill in the bowels of the earth. They were
then led to the haulage engine-room and into the workings, where they
witnessed the effects of the light. At the latter point, while, of
course, the visitors were at a safe distance, a shot was fired, bringing
down a large mass of coal. Having spent fully an hour below ground, the
party returned to the surface.--_Colliery Guardian_.
* * * * *
LIGHTNING AND TELEPHONE WIRES.
M. Bede, of Brussels, has an article in _L'Ingenieur-Conseil_ on the
above subject. He considers that a system of such wires forms the best
and most complete security against lightning with which a town can be
provided, because they protect not only the buildings in which they
terminate, but also those over which they pass. At each end they
communicate with the earth, and thus carry off safely any surplus
of electricity with which they may become charged. It is, however,
important that they should be provided with lightning conductors of
their own, to carry off such surplus directly from the transmission wire
to the earth wire, without allowing it to pass through the fine wires of
the induction coils, which it might fuse.
Such lightning conductors usually consist of a toothed plate attached to
one wire, close to another plate not toothed attached to the other wire.
The copper even of such a conductor has been melted by the powerful
current which it has carried away. In telephonic central offices, M.
Bede has seen all the signals of one row of telephone wires fall at the
same moment, proving that an electric discharge had fallen upon the
wires, and been by them conveyed to earth.
This fact shows that wires, even without points, are capable of
attracting the atmospheric electricity; but it must be remembered that
there are two points at every join in the wire. M. Bede insists strongly
upon the uselessness of terminating lightning conductors in wells,
or even larger pieces of water. The experiments of MM. Becquerel
and Pouillet proved that the resistance of water to the passage of
electricity is one thousand million times greater than that of iron;
consequently, if the current conveyed by a wire one square mm. thick
were to be carried off by water without increased resistance, a surface
of contact between the wire and the water of not less than 1,000 square
meters must be established.
It is obvious that a wire let down into a well is simply useless. On
the two-fluid theory, it offers no effectual way of escape to the
terrestrial electricity; according to the older views, it would be
absolutely dangerous, by attracting more electricity from the clouds
than it could dispose of. The author advocates connecting lightning
conductors with water or gas pipes, which have an immense surface of
contact with the earth.
* * * * *
CONDITION OF FLAMES UNDER THE INFLUENCE OF ELECTRICITY.
The experiments of the author have been principally directed to the
alterations in shape and color produced in a flame when under the
influence of positive or negative electricity. The flames were arranged
so as to form one electrode of a frictional machine. When charged with
positive electricity the flame became more blue, narrower, and pointed
at the top, while little or nothing of the result was observed in
negative flames.
A peculiar result is that the end of a negative flame returns to its own
conductor, and that, according to the intensity of the electricity, and
also depending on the width of the burner, this turning back of the
flame is either intermittent or constant. Most noticeable are these
results:
When the flame rises from a circular burner, or when burning round a
metallic cylinder, in the latter case it returns to the metallic surface
according to the intensity of electricity in an arc or angle, while the
point of the flame divides into two branches, which separately perform
more or less equal movements. If a body connected to the earth by a
conducting wire is held opposite the flame at some distance, the flame
will in all cases bend toward it; as the body is brought closer,
the flame, if negative, will be repulsed, and, if positive, will be
attracted, at least the upper luminous part of the flame, while the
lower dark body of flame is also repulsed.
This phenomenon explains why a positive flame will burn through wire
gauze, while a negative flame remains below the gauze. The positive
flame becoming pointed explains the fact that this will drive a small
fan wheel, while a negative flame will only just move it.
All these results are most prominently obtained with a pure gas flame, a
stearine, wax, or tallow candle, very indifferently with a spirit flame,
and least from a Bunsen flame rich in oxygen. They may not only be
obtained with flames electrified direct, but also when placed under the
influence of a long "Holtz" machine.
A flame placed between two small disks on the machine bends toward the
negative pole, becomes widened, and, at a certain point of electric
intensity, commences to vibrate and oscillate, exhibiting a peculiar
stratification. Since these phenomena are also least observed in flames
rich in oxygen, it appears to be a general law that carbon and hydrogen
are more strongly attracted by the negative pole, while oxygen is
more attracted by the positive pole, probably like in all polar
differentially attractions, in consequence of a peculiar unipolar
conductivity of the substances.
The return motion of the flame the author explains thus: The point
of the flame loses more electricity by influence than it receives by
conductivity. A paper strip fixed at one end to a large ball shows
similar movements when its free end is pointed and made conductive.
Why principally the negative flame returns may be explained in two
ways--either the point of the flame loses much by radiation, or the base
of the flame is a bad conductor. The former explanation would agree with
the experiments made by Wiedemann and Ruhlmann, the latter with Erdman's
theory of unipolar conductivity of flames. This theory is still further
supported by the resistance on the negative electrodes noticed by
Hittorf, which almost explains Erdman's experiments, because if negative
electricity enters a flame with greater difficulty, then positive
electricity must leave a flame with difficulty.--_W. Holtz, in
Wiedemanris Beiblaetter to Poggendorfs Annalen._
* * * * *
THE ELECTRIC STOP-MOTION IN THE COTTON MILL.
The number of inventions for use as stop-motions in and about the
various machines in the cotton mill has been to a certain extent
something like the search after perpetual motion. Very available and
quite satisfactory stop-motions have for a number of years been employed
wherever the thread or sliver has been twisted so that strength was
given it to resist a slight amount of friction, but the main trouble
in the mill has been done after the sliver leaves the railway head and
during its transit in the various processes employed between the railway
head and the spinning frame or mule. Every carder or spinner knows that
where an injury comes to the sliver because the sliver is soft, but
partially condensed and very susceptible to injury, the injury is
magnified and multiplied in every successive process. Virtually the
field was long since abandoned for an accurate quick-working motion that
should be applicable to any and all the machines and to every sliver or
strand of the machine.
This invention was solved practically about two years since, and is
now being employed as applied to drawing frames, doublers, speeder,
intermediate, and slubber. It is a very cunning mechanical appliance,
too, and has found favor to a great extent in England, where several
thousand heads of drawing and speeders are already supplied.
This invention was exhibited at the Centennial in 1876, although in a
somewhat crude state. Since that time it has been materially improved,
and mechanically is very nearly perfect now. Many attempts have been
made to apply a stop motion, which should be quick in its movement and
accurate in its result, to carding engines or the card, not one of
which, until the application of electricity, was worth the time spent in
putting it on. With the electric motion, however, all this is changed,
and the electric attachments are not of necessity so fragile as to be
un-mechanical or to be not practical. The advantage has also been
taken, in a mechanical way, of using cotton as one element, and, being
non-conducting, so that no trouble shall arise from contact with the
working parts of the electrical apparatus with the cotton itself.
To take into consideration all the possibilities that exist from the
railway can to the front of the fine speeder is not needed by the
practical reader, and would be useless to any other. The principle of
this invention is the supplying of a magneto-electric current from
a small magneto-electric machine attached to the card, speeder, or
whatever machine it may be applied to which generates the current, and
this machine is driven by a small belt from the main driving shaft.
The machine in itself weighs but a few pounds, and can be driven by a
half-inch or three quarter-inch belt, and requires a little more power
than a light-running sewing machine.
One pole of the magneto-electric machine is connected by means of a rod
or wire to the machine frame upon which it is to be used, and the
other pole to the electromagnet in the ordinary way of conductivity
of current, which means stretching the wire from one to the other. An
armature is arranged so that when a thread is broken or a sliver or a
strand of roving, the armature drops into a ratchet wheel; this ratchet
wheel is made to revolve by the belt, and whenever it is impeded or
stopped in its course it acts upon mechanism which throws the driving
belt of the machine upon the loose pulley. Electrical contact is made by
a very simple contrivance, and these attachments are only to act in the
case of a breakage of a thread or strand.
As applied to a card, the calender rolls are both connected, one with
the negative and one with the positive pole; when the sliver of cotton
is between the calender rolls there is no connection, but if the sheet
breaks down between the cone and the calender roll, the moment the
calender rolls come in contact the electrical attachment operates and a
stoppage ensues; and in the case, as with the American system, where a
number of cards are used in a railway, this electric contact may be used
for either one of two purposes-to stop the feeding of cotton into the
card, or to ring a bell sharply and continue ringing it until the sliver
is put between the calender rolls again and the card set to delivering
cotton.
In drawing frames it may be attached so that, in the case of a breakage
between the front roll and the calender roll, the electric machine acts;
in the case of a lap upon one of the rolls or one end of the roll, or
in case of breakage of the sliver at the back of the machine, in either
case a stoppage would be instantly produced.
In being applied to the slubber a breakage either at the front or back
can be arranged for. Upon intermediates the breakage of either one of
the strands, if the machine was running two into one, from the creel to
the roller, would cause the stoppage of the machine, or the breaking or
tangling of ends between the front roll and the nose of the flier.
There are many other places where this motion can be applied. With
mechanical means we require motion; with electricity we require simple
contact of two differently arranged surfaces, and this can always be
had by letting the cotton drop out from between the rollers; no radical
changes are necessary, and we are glad to find that this electrical
attachment is meeting with a very good success in England, France,
and, so far, in the United States, and, undoubtedly, further and more
extended opportunity will be found for this application.--_Textile
Record_.
* * * * *
ON THE PROGRESS AND DEVELOPMENT OF THE MARINE ENGINE.
[Footnote: A paper recently read before the Society of Mechanical
Engineers by F.C.Marshall.]
The author began by referring to a paper read at the Liverpool meeting
in 1872, by Mr. F. J. Bramwell, F.R.S., on "The Progress effected in
Economy of Fuel in Steam Navigation, considered in Relation to Compound
Cylinder Engines and High-pressure Steam;" then proceeded to continue
the subject from the date of that meeting, to trace out whether any, and
if so what, progress had been made; further, to consider whether or no
we have reached the finality so strongly deprecated by Sir Frederick
Bramwell in the discussion referred to, and, if not, then in what
direction we are to look for further development.
From a table it would seem that the steam pressures are now much higher,
the boilers have less heating surface, and the cylinders are much
smaller for the indicated horsepower developed than in 1872; and at the
same time the average consumption of fuel is reduced from 2.11 lb. to
1.828 lb., or by 13.38 per cent.
MARINE ENGINES.
The author then briefly described the modern marine engine and boiler.
The three great types of compound engines may be placed as follows in
the order of their general acceptance by the shipowning community: (1)
The two-cylinder intermediate-receiver compound engine, having cranks at
right angles. (2) The Woolf engine in the tandem form, having generally
the high-pressure and low-pressure cylinders in line with each other,
but occasionally alongside, and always communicating their power to one
crank. Such a pair of engines is used sometimes singly, oftener two
pairs together, working side by side to cranks at right angles; recently
three pairs together, working to cranks placed 120 deg. apart. The
system affords the opportunity of adding yet more engines to the
same propeller to an indefinite extent. (3) The three cylinder
intermediate-receiver compound engine, with one high and two
low-pressure cylinders, the steam passing from the high-pressure
cylinder into the receiver, and thence into the two low-pressure
cylinders respectively. The cranks are placed at equal angles apart
round the crank shaft, so as to balance the forces exerted upon the
shaft.
These three types may be said to embrace all the engines now being
manufactured in this country for the propulsion of steam vessels by the
screw propeller. In their leading principles they also embrace
nearly all paddle engines now being built, whether the cylinders be
oscillating, fixed vertically, or inclined to the shaft.
The compound engine, in fact, in one of these three forms, may now be
said to be universally adopted in this country; and the question of the
relative value of simple expansion in one cylinder, and of compound
expansion in two or more cylinders, which agitated the minds of some of
our leading engineers ten years ago, is now practically solved in favor
of the latter.
THE MARINE BOILER.
The marine boiler of to-day is in all its main features the same as it
was ten years ago. The single-ended boiler, made with two, three, and
sometimes four furnaces, is the simplest form, and for all powers
under 500 indicated horse power is the most generally adopted. The
double-ended form is largely used. It has been found more economically
efficient than the single-ended form, by as much as ten per cent, in the
writer's own experience. It is generally adopted for engines of large
power, but for small power is inconvenient, owing to its occupying more
room lengthwise in the vessel, and also involving two stokeholds and
therefore more supervision. At one time great difficulty was found
in keeping the bottoms of boilers of this kind tight. Owing to their
length, the unequal expansion due to different temperatures at the
top and bottom caused severe racking strains on the bottom seams and
riveting--so severe in some cases as to rend the plating for a large
part of the bottom circumference of the shell. This difficulty has now
been to a large extent got over, in consequence of the greater attention
given to the form and direction of the water spaces in the boiler
itself, so as to induce circulation of water; the introduction of the
feed-water at the top instead of near the bottom; the more careful
management now usual on the part of engineers; and lastly, the use of
larger plates, welded horizontal seams, drilled rivet holes, and more
perfect workmanship throughout. A modification of double-ended boiler is
that introduced by Mr. Alfred Holt. It has many decided advantages,
but is costly to make. The formation of the two ends into separate
fire-boxes leaves the bottom of the boiler free to adapt itself to the
variations of temperature to which it is exposed. The separation of the
furnaces from the combustion chamber, excepting through the opening
afforded by a connecting tube, is an advantage in the same direction,
and avoids almost entirely the racking strains due to irregular furnace
action. The weight of water carried is less, and that of the boiler
may also be made less; while the elliptical form of the two ends gives
greater steam space.
A type of boiler largely used in her Majesty's Navy, somewhat like a
locomotive boiler, is highly efficient in regard to weight and power
developed. Many examples have yielded one indicated horse-power in the
cylinders for every three square feet of heating surface, under natural
draught and with a very moderate height of funnel; and this with a
consumption of fuel not exceeding 21/2 lb. per indicated horse-power per
hour under a working pressure of 60 lb. With the aid of a steam jet in
the funnel, the heating surface per indicated horse-power has fallen
below 21/2 square feet. The large water surface afforded for escape
of steam secures almost entire freedom from priming, without the
incumbrance of steam domes; and the large combustion chamber allows of
the thorough combustion of the gases before their passage through the
tubes. The locomotive type of boiler has lately occupied the writer's
attention, with a view to its more definite introduction into marine
work. The difficulties, however, which lie in the way of applying it to
steamers going long voyages are very great. The principal difficulty
lies in the necessity of burning a large quantity of fuel in a very
limited space and time. This can only be done either by direct pressure
or exhaust action applied at the furnace. In other words, we must either
exhaust the funnel, which will absorb a large amount of power, but would
be comparatively easy of application; or our stokers, as is the case
with our miners, must work under a pressure of air.
STEEL BOILERS.
The writer stated that his experience in the manufacture and working of
steel boilers was satisfactory. Many steel boilers of sizes varying from
six feet diameter to fourteen feet six inches diameter have left the
works at St. Peter's since 1877, when the first was made; and in no
case has there been a failure of a plate after being put into a boiler,
either in the process of manufacture or in working at sea. The mode
of working is as follows: For shell plates, from five-eighths inch
to seven-eighths inch thick, to warm each to a dark red heat before
rolling, having previously drilled a few holes to template for bolting
the strakes together; the longitudinal seams are usually lap joints
treble riveted, requiring the corners to be thinned, which is done after
rolling. The furnace plates are generally welded two plates in length,
and flanged to form Adamson rings, and at the back end to meet the tube
plate; the back flame-box plates are flanged, also the tube plates and
front and back plates; and wherever work is put on to the plate it
is annealed before going into the place. The rivet holes are drilled
throughout. In the putting together the longitudinal seams of the
thicker plates of the shells, great care is always taken to set the
upper and under plates for the lap to their proper angle before they
are bolted together, a point generally overlooked by the practical
boilersmith.
CORROSION OF BOILERS.
The question of corrosion is one which is gradually being answered as
time goes on; and so far very satisfactorily for steel. Some steel
boilers were examined a few weeks ago which were among the first made;
and the superintending engineer reports: "There is no sign of pitting
or corrosion in any part of the boiler; the boilers are washed out very
carefully every voyage, and very carefully examined, and I cannot trace
anything either leaking or eating away. No zinc is used, only care in
washing out, drying out, and managing the water." This is the evidence
of an engineer with a large number of vessels in his charge. On the
other hand, some of the most prominent Liverpool engineers always use
zinc, and take care to apply it most strictly. The evidence of one
of them is as follows: "We always fix slabs of zinc to most boilers,
exposing not less than a surface of one square foot for every twenty
indicated horse-power, and distributed throughout the boiler. This zinc
we find to be in a state of oxide and crumbling away in about three
months. We then renew the whole, and find this will last twelve months
or more, when it is renewed again. Meanwhile we have no pitting and no
corrosion; but on the contrary, the interior surfaces appear to have
taken a coating of oxide of zinc all over, and we have no trouble with
them."
HOW THE MARINE ENGINE MAY BE IMPROVED.
Then the writer considered our present marine engine as to its
efficiency and capability of further improvement. The weight of
machinery, water, and fuel carried for propelling ships has not had due
attention in the general practice of engineers. By the best shipping
authorities the writer is assured that every ton of dead weight capacity
is worth on an average L10 per annum as earning freight. Assuming,
therefore, the weight of the machinery and water of any ordinary vessel
to be 300 tons, and that, by careful design and judicious use of
materials, the engineer can reduce it by 100 tons, without increasing
the cost of working, he makes the vessel worth L1,000 per annum more to
her owners. That there is much room for improvement in this direction is
shown by the following statement, giving, for various classes of ships,
the average weight of machinery, including engines, boilers, water, and
all fittings ready for sea, in pounds, per indicated horse power:
Lb. per I. H. P.
Merchant steamers.......................... 480
Royal Navy................................. 300
Engines specially designed for light draught
vessels...................................280
Royal Navy, Polyphemus class (given by Mr.
Wright).................................. 180
Modern locomotive.......................... 140
Torpedo vessels............................. 60
Ordinary marine boilers, including water... 196
Locomotive boilers, including water......... 60
The ordinary marine boiler, encumbered as it is by the regulations of
the Board of Trade and of Lloyds' Committee, does not admit of much
reduction in the weight of material or of water carried when working.
The introduction of steel has reduced the weight by about one-tenth; but
it will be the alteration of form to the locomotive, tubulous, or some
other type, combined with some method of forced draught, to which we
must look for such reductions in weight of material and water as will be
of any great commercial value. The engine may be reduced in weight by
reducing its size, and this can only be done by increasing the number of
revolutions per minute.
It has hitherto been the practice to treat the propeller as dependent
upon the size of engines, draught of water, and speed required. This
process should be reversed. The propeller's diameter depends on the
column of water behind necessary to overcome the resistance in front of
it due to the properties of the vessel. This fixed, the speed will then
fix the number of revolutions, which will be found much greater than is
usual in practice, and from this the size of the engines and boilers
will be determined. Great saving in weight can be effected by careful
design and judicious selection and adaptation of materials, also by the
substitution of trussed framing and a proper mode of securing the engine
to the structure of the vessel, as worked out in H.M.S. Nelson, by Mr.
A. C. Kirk, of Glasgow, and in the beautifully designed engines by Mr.
Thornycroft, in place of the massive cast-iron bedplates and columns of
the ordinary engines of commerce. The same may be said of the moving
parts. In fine, the hull and engines should be as much as possible one
structure; rigidity in one place and elasticity in others are the
cause of most of the accidents so costly to the ship-owner; under such
conditions mass and solidity cease to be virtues, and the sooner their
place is taken by careful design, and the use of the smallest weight
of material--of the very best kind for the purpose--consistent with
thorough efficiency, the better for all concerned.
CONSUMPTION OF FUEL IN MARINE ENGINES.
Coming to the question of the consumption of fuel, a considerable saving
has been effected in nine years, as shown in the following table:
Item. 1872. 1881.
Working pressure, lb. per sq. in......... 52.5 77.4
Heating surface per I. H. P., sq. ft.... 4.64 3.919
Piston speed, feet per min.............. 376 467
Coal burnt per I. H. P., lb.............. 2.11 1.828
This shows a saving equal to 13.38 per cent, in quantity of fuel
consumed. Mr. Marshall then read a letter from Mr. Alfred Holt, of
Liverpool, bearing on this subject, in which Mr. Holt spoke favorably of
the single-crank engine, and stated his belief that the compound system
would ere long be abandoned for the simple engine. He is endeavoring to
feel his way to using the steam in one cylinder only, and so far the
results have been encouraging, and he is now fitting a 2,200-ton vessel
on that system. He is also endeavoring to do without a crank shaft, the
forward end of the screw shaft carrying an ordinary crank with overhung
pin. This experiment also promises satisfactorily. In his opinion the
great improvement of the immediate future is to increase the steam
production of our boilers. A ton weight of a locomotive boiler produces
as much steam as six tons of an ordinary steamboat boiler.
Mr. Holt speaks of the coal account as one of the minor disbursements
of a steamer. He does not give the ratio which coals bear to the total
disbursements, but from other reliable sources Mr. Marshall found that,
according to the direction of the voyage, it varies from 16 to
20 percent.--or, say, an average of 18 per cent.--of the total
disbursements, in a vessel carrying a cargo of 2,500 tons. This will
represent to-day about L3,000 per annum, and in 1872, at equal prices,
the cost would have been L3,750--showing a saving of L750, equal to a
dividend of, say, 3 per cent. on the value of the ship. Again, the cost
of coal per mile run for such a vessel, in 1872, would have been at
least 161/2d.; to-day it does not exceed 13d.
EVAPORATIVE EFFICIENCY OF MARINE BOILERS.
The marine boiler as now made is very efficient, but if the quantity of
steam used be considered in relation to the increased pressure, it will
be seen that the boiler of to-day is little if anymore efficient than
that of ten years ago. The present boiler has an evaporative efficiency
of about 75 per cent., and cannot be much improved so long as air
is supplied to the furnace by the natural draught. To increase the
efficiency from 75 to 82.5 per cent. would require about double the
heating surface, the weight of boiler and water being also doubled,
while the gain would be only 10 per cent. Mr. Blechynden's formula, used
in Mr. Marshall's works for weights of cylindrical marine boilers of the
ordinary type, and for pressures varying from 50 lb. to 150 lb., is as
follows:
W = (P + 15) (S + D squared L) / C
or W = 2S (P + 15) / C
when S = D squared L, which is a common proportion.
Here W = weight in tons.
P = working pressure as on gauge.
S = heating surface, in square feet.
D = diameter, in feet.
L = length, in feet.
C = a constant divisor, depending on the class of
riveting, etc. For boilers to Lloyds' rules,
and with iron shells having 75 per cent.
strength of solid plate, C = 13,200.
This formula, if correct--and it is almost strictly so--would give the
relative weight of boilers per sq. ft. of heating surface, for 105 lb.
and 150 lb. total pressure, assuming we wish to increase the efficiency
10 per cent, as follows:
Weight at 105 lb. = 105 x 1 / C
Weight at 150 lb. = 150 x 1.75 / C = 263 / C
Hence the ratio of weight = 263 / 105 = 2.5
In other words, the boiler with the higher efficiency would weigh two
and a half times that with the lower efficiency. In the case of a vessel
of 3,000 tons, with engines and boilers of 1,500 indicated horse power,
the introduction of locomotive boilers with forced draught would place
at the disposal of the owner 150 tons of cargo space, representing
L1,500 per annum in addition to the present earnings of such a vessel.
MARINE LOCOMOTIVE BOILERS.
Mr. Thornycroft has for some years used the locomotive form of boiler
for his steam launches, working them under an air pressure--produced
by a fan discharging into a close stokehold--of from 1 in. to 6 in. of
water, as may be required. The experiments made gave an evaporation of
7.61 lb. of water from 1 lb. of coal at 212 deg. Fahr., with 2 in. of
water pressure, and 6.41 lb. with 6 in. of pressure. These results are
low, but it is to be remembered that the heating surface is necessarily
small, in order to save weight, and the temperature of the funnel
consequently high, ranging from 1,073 deg. at the first pressure, and
1,444 deg. at the 6 in. With the ordinary proportions of locomotive
practice the efficiency can be made equal to the best marine boiler
when working under the water pressure usual in locomotives, say from
3 in. to 4 in., including funnel draught.
It has fallen to the lot of the writer to fit three vessels recently
with boilers worked under pressure in closed stokeholds. The results,
even under unfavorable conditions, were very satisfactory. The pressure
of air would be represented by 2 in. of water, and the indicated horse
power given out by the engines was 2,800, as against 1,875 when working
by natural draught, or exactly 50 per cent. gain in power developed.
Mr. Marshall then proceeded to refute the arguments which may be urged
against the use of the locomotive boiler at sea, and which we need not
reproduce. Coming to the engines, Mr. Marshall said that the total
working pressure of to-day may be accepted as 105 lb., or equal to seven
atmospheres. If it were boldly accepted that eleven atmospheres, or 165
lb., were to be the standard working pressure, the result would be a
gain of 14.55 per cent., provided no counteracting influence came into
play. Of course, there are forces which war against the attainment of
the full extent of this advantage, viz., the greater condensation in the
cylinders and loss in the receiver or passages.
In regard to the former, it may be questioned whether by steamjacketing
the high pressure cylinder, correctly proportioning the steam passages,
and giving a due amount of compression in both cylinders, this may not
be reduced far below the generally received notion; and the latter cause
of loss may be considerably reduced in its effect by a more carefully
chosen cylinder ratio. The ratio usually adopted, between 3.5 and 4 to
1, whether the pressure be 70 lb. or 90 lb., may well be questioned.
With a cylinder ratio of 2.95 to 1, the economic performance is very
good, and equal to any with the higher ratio. A lower cylinder ratio has
another advantage of considerable value, viz., that the working pressure
can be much reduced as the boilers get older, while by giving a greater
amount of steam the power may be maintained--at an extra cost of steam,
of course, but not so great a cost as with higher ratios. The cut-off
in the high-pressure cylinder usually takes place at about 0.6, and
the ratio of expansion has decided the ratio of cylinders. The use of
separate starting valves in both cylinders obviates that necessity.
The difficulties in the way of taking advantage of the higher economic
properties of greater pressures than hitherto used on board ship, are,
it is submitted, not insuperable, and it would be to the interest of all
that they should be firmly and determinedly met. It may be accepted as
an average result that the Woolf engine, as usually arranged, will use
10 per cent. more steam than the receiver engine for the same power.
Of the three-cylinder receiver type the data are insufficient to form a
definite opinion upon; but so far the general working of the Arizona is
stated to be as good, economically, as any of the two-cylinder receiver
class. The surface condenser remains as it was ten years ago, with
scarcely a detail altered. In most engines it remains a portion of the
framing, and as such adds greatly to the weight of the engine.
It is a question seriously worth consideration whether or no the surface
of tubes can be reduced. The practice at present is to make the surface
one-half the boiler surface as a minimum, that is, equal to about 2
square feet per indicated horse power. In practice, the writer has found
1.4 square feet per indicated horse power to maintain a steady vacuum of
271/2 inches.
Mr. Marshall has just completed six pairs of engines for three twin
screw ships, having steel shafts of 10 inches diameter, and has in each
case run the engines at 120 revolutions per minute, while indicating
1,380 horse power from each pair for ten to fifteen hours without
stopping; and in no case has a single bearing or crank pin warmed or
had water applied, the surfaces on examination being perfect. In these
engines all working bolts, pins, and rods, except the piston and
connecting rods, are of steel, all rods in tension being loaded to 8,000
lb. per square inch. The boilers are of the Navy type, made throughout
of Siemens-Martin steel plates, riveted with steel rivets, all holes
drilled. Furnaces are welded and flanged; the tubes are of brass. In
comparison with an ordinary merchant steamer's iron boilers of the
double ended type, they weigh, including water and all appurtenances, as
follows:
Double ended Type. Navy Type.
Weight, tons............ 135 ........... 146
I. H. P................. 1,400 .......... 2,760
Draught................ Natural ......... Forced.
SCREW PROPELLERS.
The screw propeller is still to a great extent an unsolved problem. We
have no definite rule by which we can fix the most important factor of
the whole, namely, the diameter. Mr. Froude has pointed out that by
reducing the diameter, and thus the peripheral friction, we can increase
the efficiency; and this is confirmed by cases--of Iris reduced 2 feet
3 inches, and the Arizona reduced 2 feet. This must, of course, be
qualified by other considerations. The ship has by her form a definite
resistance, and a certain speed is required; if the propeller be made
too small in diameter, the ship will not be driven at the required
speed, except at serious loss in other directions. This question was too
large and complicated to be dealt with here, and should, in the first
instance, be made the subject of careful and extended experiment, on
which a separate paper should be written.
To sum up the whole. Progress has been made during the past nine years,
and in the following particulars:
1. The power of the engines made and making show a great increase. 2.
Speeds hitherto unattainable are now seen to be possible in vessels of
all the various classes. 3. The consumption of fuel is reduced by 13.38
per cent. on the average; and numbers of vessels are now working on much
less coal than that average, while the quality of the coal is in nearly
all cases very inferior, so that it is not unfair to take credit for
20 per cent. reduction. 4. The working pressures of steam are much
increased on the average, and are still increasing; many steamers now
being built for 120 lb. per square inch, while 90 lb. is the standard
pressure now required.
* * * * *
STEAM FERRY BOATS OF THE PORT OF MARSEILLES.
The small steam ferry boats represented in the accompanying cut are
doing service in the port of Marseilles, and the following description
of them has been given by Mr. Flecher in the _Bulletin de la Societe des
Anciens Eleves d'Arts et Metiers_:
All those who are acquainted with the Old Port of Marseilles know the
inconvenience of communication between one shore and the other, and the
high price of ferriage by row boats. To obviate this, Captain Advient
has been struck with the happy idea of creating a cheap steam service
(fare one cent), thus supplying a genuine want in the modes of
locomotion of the city.
The building of these ferry boats, on a system providing for the use of
separate hulls, was confided to Messrs. Stapfer, De Duclos & Co., of
Marseilles, whose well-known reputation was a sufficient guarantee that
the problem would be successfully solved.
There existed difficulties of two natures: The first of these related to
the stability of boats such as this, having their engine, boiler, supply
of coal, forty passengers who might all occupy one side of the vessel, a
central superstructure, with roof; and, finally, all the weight centered
on five feet of the deck, with nothing below to counterbalance it except
the hollow hulls and two three-foot compartments, each placed toward the
central portion of the hulls and designed as fresh-water reservoirs
for the steam generator. The second difficulty was to obtain the best
utilization possible of a screw placed in the current between the hulls
and upon a shaft inclined toward the stern, that is, "stern" by analogy,
for there is no distinction of fore and aft in ferry boats.
[Illustration: STEAM FERRYBOATS OF THE PORT OF MARSEILLES.]
The conditions of the problem were finally fulfilled to the satisfaction
of all concerned, and especially to that of the public.
The hulls, navicular in form and having a flat bottom, are constructed
of one-tenth inch iron plate and 40x40 angle iron. Their dimensions
are: Length, 33 feet; breadth, 31/4 feet; and depth, 5 feet. The internal
distance between the two shells is 71/4 feet. These hulls, having
absolutely water-tight decks, are connected below by tie bars of flat
iron, and above by vertical stays 1 foot in length, which serve to
support the floor-planks of the deck and boilerplate flooring of the
engine-room. The engine-room, which is 191/2 feet long by 5 feet wide, is
constructed of varnished pitch-pine, with movable side-shutters of teak.
The roof, of thin iron plate, is provided with a ventilator to allow of
the escape of hot air.
The passengers, to the number of forty or fifty, can move about freely
from larboard to starboard, or from stem to stern, or seat themselves
on the benches running along the inside of the guard railing on the two
sides of the vessel. They are protected from rain by a roof, and from
the rays of the sun by a curtain extending along the sides.
Although the usual method of landing is fore and aft, gangways have been
provided at the sides for side-landing should it become necessary.
The general appearance of one of these boats may be likened to that of a
floating street-car. Finally, a small apartment, provided with benches,
is provided for the use of those passengers who might be taken sick, or
for office purposes, if need be.
The total weight of one of the boats is divided up as follows:
Forty passengers................ 6,200 pounds,
Engine and boiler............... 6,600 "
Ballast, water, and equipment... 9,900 "
Deck and superstructure......... 6,600 "
Hull and accessories............12,500 "
______
Total...........................41,800 "
or a displacement of about 700 cubic feet, corresponding to a maximum
draught of 3.7 feet. The mean speed is 4 knots, or 41/2 miles per hour, a
great velocity being unnecessary, owing to the small distance to cross
in a port often obstructed by the general movement of vessels taking
place therein.
The engine is from 16 to 18 horse-power. Its frame is inclined
perpendicularly to the direction of the screw-shaft, the extremity of
which is supported near the screw by a strengthened cross-stay serving
as a pillow-block. The cylinder is 8 inches in diameter, and the piston
has a stroke of 6 inches, causing the screw (which is 31/4 feet diameter)
to make 200 revolutions per minute. The screw, although it has a wide
surface of thrust, gives, nevertheless, a recoil of about 30 per cent.,
because of its location between the hulls and its oblique action on the
shaft.
The steam is furnished by a tubular boiler having an internal fireplace
and a heating surface of sixteen square meters, the draught being
effected by the exhaust of the engine. This boiler, which is tested
up to 14 pounds, is fed by a steam pump, or by a pump actuated by the
engine. The feed pumps take water successively from one or the other of
the reservoirs in the hulls. The reservoirs are filled in the morning,
and their level is ascertained by two small and ingenious Decondun
indicators, the dials of which are placed against the walls of the
engine-room.
Taken altogether, these little boats are well arranged and quite
handsome; and, since they were put into service in June, 1880, they have
proved a great convenience to the hard-working and active population for
which they were built.
* * * * *
OPENING OF A NEW ENGLISH DOCK.
In July last, Admiral the Duke of Edinburgh, with the Naval Reserve
Squadron under his command, arrived in the Firth of Forth and anchored
in Leith Roads. His Royal Highness performed the ceremony of opening the
new dock at Leith, which has been named after him. The "Edinburgh" Dock
at Leith, which was commenced in 1874, consists of a center basin 500
ft. long and 650 ft. wide, and two basins 1,000 ft. long and 200 ft.
wide, separated by a jetty having a width of 250 ft. The total amount
of masonry in the wet docks is 100,000 cubic yards. The north and south
quays are each 1,500 ft. long, and the two sides of the jetty 1,000 ft.
long each, having a total quayage in connection with the dock of 6,775
ft. The walls are 15 ft. thick at the base, narrowing in two tiers to
8 ft. The new dock will cost altogether about L300,000. Leith now
possesses five docks and a total quayage of three miles 808 yards, 1,234
yards of which is the old portion. These works have been constructed, at
a cost of nearly one million sterling, by the Leith Dock Commissioners,
whose chairman, Mr. James Currie, presented an address to the Duke of
Edinburgh, on board the flag-ship H.M.S. Hercules, giving an account of
their affairs. The other docks at Leith are named the "Old Dock," the
"Queen's Dock," the "Victoria," the "Albert," and the "Prince of Wales
Dock." The opening ceremony was arranged to consist of the steamer
Berlin, with his Royal Highness and the Dock Commissioners on board,
accompanied by Sir Donald Currie, M.P., and other gentlemen, passing
through the entrance from the Albert Dock to the new dock, across which
a blue ribbon had been stretched. At the moment when the ribbon snapped
asunder, under the bow of the Berlin, the Duke of Edinburgh, stepping
forward on the upper deck of the steamer, said, "I have now the
gratification of declaring this dock open, and calling it the Edinburgh
Dock." On this announcement being made, a signal was conveyed to a
battery of guns, posted on the sea wall of the new dock, from which a
party of the Royal Artillery fired a Royal salute. The steamer, having
gone round the new dock, was brought up at the quay at the west. His
Royal Highness the Duke of Edinburgh, with Prince Henry of Prussia, the
officers of the fleet, and the Commissioners, disembarked and proceeded
to the saloon in the new dock, where luncheon in honor of the occasion
was given by the Leith Dock Commissioners.--_Illustrated London News,
Aug. 6._
[Illustration: OPENING OF A NEW ENGLISH DOCK.]
* * * * *
IMPROVED GRAIN ELEVATOR.
The illustration shows the apparatus at work transferring a cargo of
grain from the hold of a ship by means of an elevating band fitted
with buckets. By a simple contrivance shown in the engraving by
diamond-shaped squares, the elevating band can be shortened or
lengthened at pleasure, so as to suit it to the position the grain to be
elevated occupies in the ship or barge. When the grain is elevated to
the point whence it is to be transferred to the granary, railway
truck, or other destination, the band travels horizontally on suitable
bearings, the buckets being so constructed that in traveling they retain
their load intact. The contrivance for lengthening and shortening the
bucket band is an application of the "lazytongs" device, which is well
known. The float of the elevator is shown at the left hand of the
engraving, and, as seen in the latter, there is an automatic weighing
machine, by which the material may be weighed as it is delivered, before
it goes to the bottom of the elevator, to be again transferred by its
means to the barge or granary. Simplicity, efficiency, and adaptability
to any position in which elevators of this class are desirable, are the
claims the patentees, Messrs. Behrns & Unruth, Lubeck, make for the
advantages of their apparatus.--_London Miller_.
[Illustration: IMPROVED FLOATING ELEVATOR.]
* * * * *
IMPROVED DREDGER.
We illustrate below a useful type of dredger made by Messrs. Rennie, of
Blackfriars, England. The drawing almost explains itself. The machine
consists of a double barge or pontoon, in which is erected a derrick.
This derrick works a "spoon" dredge at the end of a lever. The spoon, as
shown, is at its lowest position. It will make a forward stroke, through
about one-sixth of a revolution, and will thus become filled with
mud and be lifted above the surface of the water. The motion will be
imparted to it by the chain and pulleys seen at outer end of the derrick
jib. The jib will then be swung round over the bank on a hopper barge
and its contents delivered. The requisite power is supplied by the steam
engine at the end of the pontoon. Messrs. Rennie have made several of
these little dredgers, which are found very useful and handy in shallow
water.--_The Engineer_.
[Illustration: SINGLE BUCKET DIPPER DREDGER.]
* * * * *
RAILWAY ALARM WHISTLE.
In order to prevent a train passing a danger signal during a fog or
snowstorm without being seen by the engineer, the Southern Railway
Company of France have attached to the locomotive a steam whistle, which
is controlled by the signal. The whistle is connected with an insulated
metallic brush placed under the engine. Between the rails there is a
projecting contact bar, faced with copper, which is swept by the brush
when the train passes. This contact piece is connected with the
positive pole of a voltaic battery, the negative pole of which is in
communication with a commutator on the signal post, from which a wire
leads to the ground. When the signal is "line clear" the passage of the
brush over the fixed contact produces no result; but when the signal
marks "danger," the commutator brings the negative pole of the battery
in direct communication with the ground, and when the brush passes over
the contact the completion of the electric current causes the whistle to
be sounded, so as to alarm the driver.--_L'Ingen. Univ._
* * * * *
FURNACE FOR THE MANUFACTURE OF SULPHIDE OF CARBON.
Sulphide of carbon (CS_2) is prepared by passing the vapors of sulphur
over charcoal heated to redness. In laboratories, charcoal and roll
brimstone are employed so as to obtain as pure a product as possible;
but sulphide of carbon having now become so important a commercial
product, and being employed for so large a number of industrial
purposes, it has been found more economical to substitute coke for
charcoal and pyrites for brimstone.
The Messrs. Labois, in their system of furnace represented herewith,
have had in view the manufacture of this product under as economical
conditions as possible, by coupling over two connected fireplaces the
retort in which the pyrites is distilled, and that in which the reaction
of the sulphur and carbon takes place.
The pyrites is fed from the hopper, A, into a distributing box, B,
furnished with a valve which is maneuvered by a lever. From thence it
descends into the retort, G, where it is roasted by the heat of the
fireplace, L. The sulphur converted into a state of vapor passes through
the conduit, R, into the coke or charcoal retort, G', which is divided
into two parts by the partition, _g g'_, of refractory clay, and heated
by the fireplace, L'.
[Illustration: LABOIS'S SULPHIDE OF CARBON FURNACE.]
The conduit, R', leads the sulphide of carbon in a state of vapor to the
condensing apparatus. The uncombined sulphur which is carried along is
deposited in the first part of the retort by the arrangement of the
partition, which permits of passage only below. The registers, V and
V', permit of the introduction of the sulphur vapor and the exit of the
sulphide of carbon being regulated.
The apparatus is so easy of installation that it may be applied without
much expense to pyrites furnaces already in operation.
Wherever a manufactory of the product is to be started, the system
recommends itself by its simplicity, and by the facility with which the
operation may be watched and conducted.
* * * * *
BROUARDEL'S DRY INSCRIBING MANOMETER.
Brouardel's manometer, represented herewith, is designed for showing
graphically variations in the pressure of gas, either at the works
during the course of manufacture, or at any point whatever in the system
of piping.
For this purpose water manometers have hitherto been employed; but,
although the indications given by these are very accurate, their form
and weight are such as to render them not easily transportable; and
then, again, considerable care is necessary in putting them in place.
Mr. Brouardel's registering manometer does not give so accurate
indications, perhaps, but it possesses, as an offset, the merit of being
very portable and easily put in place; and, besides, it inscribes the
hour at which the pressure is exerted.
The apparatus consists of a metallic cylinder, A B, which carries a
circular shoulder, C, that rests on a plate, D--the latter being put in
motion by a clock which is wound up by means of a button under the base,
E, of the apparatus. The two standards, F F, carry a crosspiece which
supports a disk that closes freely the aperture of the drum, A B, in
such a manner as not to impede its rotation.
In the interior of the cylinder there is a metallic cup which is
connected with the central reservoir by an impermeable membrane, I.
These three parts form a closed chamber, into which the pressure comes
through a tube, F, provided with a cock. A spring, M, which counteracts
the pressure, is arranged between the crosspiece, G, and the bottom of
the reservoir. The latter carries also a small rod, K, which is provided
with a cord made of braided silk. This cord runs over a pulley, N, whose
axle carries at its other end a still larger pulley, O. Toward the
middle of the latter is fixed a silken cord which hangs down on each
side, after making several turns around the pulley. To the front cord
is attached a slide, Q, moving in a vertical direction, and to which is
fixed an inscribing style, R. The other extremity of the thread enters
the hollow upright, and carries a weight which is greater than the
combined weights of the slide, the membrane, and the internal reservoir.
The upright serves as a guide to this counterpoise.
In order to use the apparatus there is affixed to the cylinder, A B, a
sheet of paper divided in a vertical direction into as many parts as
the cylinder takes hours to make one revolution. The divisions running
horizontally represent centimeters of water or of mercury, according to
the strength of the spring, M, which should be so constructed as to be
in relation with the pressure. The operation of the apparatus may be
readily understood.
[Illustration: GAS INDICATOR OF MANOMETER.]
When the gas reaches the pressure chamber, the spring, M, contracts, and
consequently the counterpoise descends, and causes the cord, O, which
carries the slide and writing style, to wind around the pulley. When the
pressure diminishes, the movement takes place in an opposite direction.
The tracing is done by means of a special form of style giving indelible
curves through the medium of colored glycerine. The position of the
point is determined in such a way as to annul the friction of the pen,
and consequently to give it greater sensitiveness.
It should be remarked that the course of the rod, K, is amplified in the
tracing of the ordinates of the pressure according to the ratio of the
diameters of the pulleys, N and O.
The apparatus may be carried by hand by means of the handle, S, either
in or out of its case. To put it in operation, it is only necessary to
connect the apparatus with a gas burner (located near the place where
the variations of pressure are to be observed) by means of rubber
tubing. The apparatus may be employed under the same circumstances as
glass and U-shaped water manometers, with the further advantage that the
results are registered, and consequently can be more easily compared.
* * * * *
CENTRIFUGAL APPARATUS FOR CASTING METALS.
The apparatus represented in Figs. 1, 2, 3, and 4 is the invention of
Messrs. Taylor & Wailes, and is designed for casting metallic objects
in annular form, its arrangement being slightly varied according to the
nature of the objects to be cast. In all cases where a special form is
to be given to the outer or inner circumference of the object, or where
it is desired to exert a pressure on the circumference, such form or
pressure is obtained by the introduction of a core which may be expanded
or contracted as need may be. For this purpose an expansible, metallic
core is employed, the arrangement of which is shown in Figs. 1 and 2,
and which is so fashioned that the inner circumference of the ring to be
cast may receive the desired form. This core is formed of the pieces, g,
g', made of cast-iron or any other material which fuses with difficulty,
and which are placed in the revolving mould in such a way that after the
cooling of the pieces the parts, g, recede by the shrinkage of the piece
and thus free the core. The parts, g, of the core are in the shape of
circular segments, and are united at their external circumference by a
flange, along with which they form a shoulder piece for the casting.
As a consequence of the rapid revolution of the mould, these parts are
pressed by centrifugal force against the molten metal which is run into
the mould.
[Illustration: CENTRIFUGAL METAL MOULDING APPARATUS.]
The plan, Fig. 2, shows the arrangement of the parts, g, g', and allows
it to be seen that the pieces, g', act as wedges against the segments,
g, and push these out so as to form a perfect circle. The molten metal
cannot become oxidized in the mould, since it is shut off from contact
with the external air by the cap, C, which covers it. Oxidation may,
however, be further prevented by passing some deoxidizing or neutral gas
into the mould. For this purpose the mould is filled before the casting
is done with some such gas as illuminating gas, carbonic acid, nitrogen,
or hydrogen.
This improved process of casting may also be employed for objects which
do not possess an exactly annular section. The moulds are then arranged
eccentrically in a frame which is made to revolve rapidly during the
cooling of the metal In this way the pieces are less strongly compressed
at the places where they are nearest the center of rotation than a the
points where the radius is greater.
Figs. 3 and 4 show section and plan of an apparatus of this kind. The
sand moulds are arranged in the frame, a b which revolves about the
axle, c. In the moulds there are iron cores, h, which press the metal
during rotation and thereby produce compact pieces.
* * * * *
APPARATUS FOR THE MANUFACTURE OF WOOD PULP.
For manufacturing wood pulp Mr. Dresel employs an apparatus such as
represented in Figs. 1 and 2, consisting of an upright cylindrical
reservoir, A, supported on a frame by means of trunnions, z. This
reservoir, which is of boiler plate, is furnished with a cover, D, which
has in its center a piece of tubing, with stop-cock, C. A series of
tubes, R, whose diameter and length are proportioned to the volume of
the boiler, A, is filled with the liquid which is contained in the
boiler, so as always to be able to rapidly produce a pressure of nine
atmospheres or more by direct heating. The flanges of the tubing are
provided with a cut-off of angle iron identical with that of the tube,
D. By means of this arrangement the cocks and the flanges, E, permit of
communication between the serpentine tubing, R, and the boiler being
interrupted; while the heat developed by the fire-place, F, causes an
active circulation in both the tubing and boiler.
[Illustration: DRESEL'S WOOD PULP APPARATUS. Fig. 1]
[Illustration: DRESEL'S WOOD PULP APPARATUS. Fig. 2]
To put the apparatus in operation the cover, D, is first unscrewed, and
there is put into the boiler a certain quantity of wood, which has been
divided up by a cutting machine of special form. Then the boiler is
filled to the proper height with the liquid necessary to dissolve the
incrusting materials, the cocks, B, being closed. Afterwards there
is fixed immediately beneath the angle-iron ring of the cover, D, a
perforated iron plate upon which the contents of the boiler rest when
the latter is turned up. Then the cover is fastened down and the boiler
is put in communication with the heating apparatus. The cocks, E and B,
are opened, so that the liquid may begin its movement in the tube, a,
the boiler, A, and the tube, n. As soon as the proper temperature
is reached for converting the wood into fiber and decomposing the
incrusting matters, the heat is shut off in case the tubing, R, is not
connected with another like boiler, and, after closing the cocks, E and
B, and shut off communication between the tubing and the boiler, the
latter is turned over and the cock, C, gradually opened in order to
allow the steam to escape. When the temperature has descended to 100 deg.
in the boiler the cover, D, may be opened, after the liquid has been
allowed to flow out through the cock, C. Next, lixiviation is effected
by connecting the cock, C, with the steam pipe, P, and causing steam
under pressure to enter the boiler, A. The action of the steam on the
contents of the latter, which are now converted into cellulose, mixed
with a large quantity of dissolved matters and of liquid, effects a
complete washing and permits of the recovery of considerable quantities
of useful chemical products. Moreover, the steam purifies, decolorizes,
and completely separates the fibers, and renders them more easily
susceptible of being bleached. Finally, the perforated bottom, S (which
is formed of two parts), is removed and the boiler emptied.
In order to have the operations under control, and for the purpose of
safety, there is riveted into the boiler, A, a tube, T, containing a
thermometer: and there is fixed to the tube, a, a pressure-gauge, M, and
a safety-valve. The level of the liquid is ascertained by means of a
gauge-cock, H.
* * * * *
RECENT PROGRESS OF INDUSTRIAL SCIENCE.
The thirty-fourth annual summer meeting of the Institution of Mechanical
Engineers began on Aug. 2, at Newcastle-on-Tyne. The following is an
abstract from the address of the president, Mr. E. A. Cowper.
He began by stating that as members of the Institution of Mechanical
Engineers, on revisiting their brother members and friends here in
Newcastle, after an interval of twelve years, they came as it were to
one of their natural homes; certainly to the home of one of the greatest
engineers that England has ever produced, and the birthplace of the
locomotive, which has done more than any other improvement, of our age
to lessen the cost of materials to the men who have to use them, and
therefore to cheapen and extend production in the most wonderful manner.
He then went on to say that it seems but a few years ago since George
Stephenson, at a meeting in 1847, proposed the resolution that the
Institution of Mechanical Engineers be formed. He was strongly supported
by a large number of the mechanical engineers of the country, and the
speaker had the honor of seconding the resolution that he be first
president. The intention was that engineers from all parts of the
country should join to form a compact body capable of discussing
and judging of all mechanical subjects and appliances. In this the
institution had been eminently successful, and it numbered among its
members mechanical engineers in every large town in the country, and has
increased in strength and importance.
The last twelve years have been marked by many very important
changes, while low prices have generally ruled. Among other causes of
fluctuations in demand and supply (and consequently in values) must be
mentioned the occurrence and the threatening of foreign wars, which
disturbed the course of commerce greatly for some years. Such causes
must be considered as extraneous to the sphere of influence possessed by
good or bad manufacturing or engineering. Mr. Cowper does not look upon
the very great expense of improved war material and implements as an
unmixed evil for this country; for it so happens that we can better meet
such outlay than any other nation, and thus our wealth gives rise to
greater power and security than our neighbors possess; while, seeing
that we are not an aggressive nation, such power tends materially at
once to the progress of this country, and to the peace of the world.
Having referred briefly to one cause of disturbance to the progress of
mechanical engineering, he named another, which at the present moment is
occupying thoughtful men to a considerable extent, namely, the arbitrary
imposition of duties and bounties for the professed object of protecting
manufactures, while in fact they constitute taxes on a nation for the
benefit of a few individuals. In some countries excessive duties have
been imposed, as against our manufactures, and it is even proposed to
increase them; while in other cases bounties are actually paid out of
the public purse to men engaged in a particular manufacture, on their
exporting to this county certain of their wares, as, for instance,
beet-root sugar.
One extremely significant lesson, resulting from high duties--which it
may be hoped will not be thrown away upon the American public--is, that
whereas our cousins on the other side of the water used to build almost
all the American "liners" of wood, they now find that, with their
excessive duties against the importation of iron and steel from England,
they cannot compete with English iron and steel ship-builders and marine
engineers. This is one of those damaging effects naturally produced
by excessive protective duties; which, while they enable American
ironmasters quickly to realize enormous fortunes, drive the American
merchants to purchase English ships, or intrust their merchandise in
English bottoms, as it is impossible to maintain protective duties at
sea.
Whatever fluctuations have occurred, it is now pretty clear that
several foreign nations have settled down to cultivate and extend their
manufactures, and we are brought face to face with the fact--which has
now been for some years growing to its present importance--that many
articles which in years gone by we thought it to be our especial
province to supply, are now produced in the very countries requiring
them. Even Spain is awakening to the advantage of producing hematite
iron from her own excellent ores, with English and Welsh coke carried
out in the same ships that bring Spanish ores to this country.
Now with regard to the possibility of any foreign nation eclipsing us in
our manufactures, he would say at once that any such successful rivalry
on their part is far worse than the effect of any duties, even if they
be prohibitive; for it means rivalry in the markets of the world, and
possibly in our own markets here at home. Therefore it behooves us
to put our house in order, and see in what way we may be enabled to
manufacture better and with greater economy. Mechanical engineering is
of such extreme importance in advancing civilization, that it is most
essential that its progress should be rapid and unimpeded.
Perhaps the very large increase in steam shipping, and the change from
sailing ships and paddle steamers to screw steamers, has been one of the
greatest improvements of recent times, and it is none the less real
or important from having been gradual, while the result to this
neighborhood has been most beneficial. This change has been due in great
measure to the introduction of very economical marine engines, chiefly
of the compound type, together with better boilers carrying a higher
pressure.
The speed and regularity of ocean steamers has also greatly improved,
and one small scientific improvement has added much to the safety of
traversing such seas as the Atlantic at a high speed--namely, the
careful and continual use of a good thermometer, to ascertain constantly
the temperature of the sea-water at the surface. For if an iceberg is
floating within a quarter of a mile--or even half a mile, if the sea is
pretty smooth--the surface water will be several degrees colder than the
rest of the sea; since the very cold fresh water, resulting from the
melting iceberg, floats on the top of the sea water for some distance.
No doubt the use of iron, and now of steel, has contributed most largely
to the increase of shipbuilding in this country. Good arrangements
of water ballast have also proved very useful; and steam cranes and
arrangements for loading and discharging cargo have greatly promoted the
use of steam colliers, enabling them to make more voyages in the year.
Closely connected with marine engineering is the great improvement in
the economy of stationary engines, which has become more fully developed
during recent years, both in reference to waterworks engines and factory
engines. In aid of stationary engines, "surface evaporator condensers"
have been found very useful, particularly where the supply of water is
very limited; and at waterworks it is now very common to pass the whole
water pumped through a surface condenser, thus giving a good vacuum
without the expenditure of any water, and with the result of only
raising the temperature of the water a very few degrees, on account of
its large volume.
Locomotives have shared to some extent in the general improvement in
machinery. The boilers are better made, and are safer at the higher
pressures now carried than they were formerly with a low pressure.
Several new valve gears of great promise have been brought forward, both
for locomotives and marine engines. Among them Joy's motion should be
again noticed. Mr. Webb says: "The engine shown at Barrow has been at
continuous work ever since the Barrow meeting, and has run 30,278 miles;
we had it in for examination on the 18th inst., and found the motion
practically as good as the day it went out of the shop, more especially
the slides, about which so many of the people who spoke at the meeting
seemed to have doubts. I do not think you could get a visiting card
between the slides and the blocks; in fact, the engine has been sent out
to work again, having had nothing whatever done to it. The first thing,
of course, that will require doing will be the tires; as far as I can
see nothing else will want doing for some time."
A very fine engineering work has now been accomplished in America in
reference to navigation, namely, the deepening of the channel at the
mouth of the Mississippi through the training of the river by jetties
and banks. In consequence, ships of large size may now go up the
river--there being plenty of deep water above the mouth--and bring down
grain cargoes, without the expense and inconvenience of transshipment,
thus reducing the freight of corn to this country. This great
improvement is the work of Captain Eads. A somewhat similar improvement
was the blowing up of about 50,000 tons of rock from the bed of the
river at the narrow pass of Hell Gate, near New York. It is to be hoped
that these good examples may spur on our friends on the Continent to
improve their harbors, so that large channel boats may cross with
comfort to the passengers, thus avoiding the excessive expense that a
tunnel would involve.
Great improvements have been made in the illumination of lighthouses
by oil lamps; a light equal to 1,300 candles has been produced by Mr.
Douglass, of the Trinity House, and now two such lights will be placed
one above the other, where required. The electric light has made such
numerous and rapid strides that it is impossible even to notice its
various applications; but on the one hand the lighting by Dr. Siemens
of four miles of dock frontage at the Albert Dock of the London and St.
Katherine Dock Company, together with the railway behind the warehouses,
and the warehouses and ships themselves, and, on the other hand, the
elegant and steady domestic light of Mr. Swan, are excellent examples
of the two extremes in this department. I believe we shall have the
pleasure of closely observing the Swan light during our visit here. The
lighthouse electric light is also a noble application of the great power
of a single electric light on the arc principle. The most powerful
electric light in the world is situated near here on the coast, between
the Tyne and the Wear. It is possible, and even probable, that one of
the great uses to which electric force will be applied eventually, will
be simple conveyance of power by means of large wires; and as a higher
percentage of power is gradually being realized, this method will become
more economical. I may mention that 60 per cent. has already been
obtained.
The invention of Messrs. Thomas & Gilchrist, by which a very large field
of ironstone is now, for the first time, made available for the purpose
of making good steel by the Bessemer process, bids fair to make very
considerable alterations in the steel-making trade, and in the hands
of Mr. E. Windsor Richards it has been made a great success, while in
Germany there are several works also using the process largely. Mild
steel is now being used to a great extent for the construction of steam
boilers as well as of ships, and in steel castings for a variety of
purposes, such as spur wheels, frames of portable engines, manhole door
frames, etc., etc. Among the uses to which steel may be put is the
manufacture of steel sleepers in place of wood. It is a very encouraging
fact that there are now, or rather there were already, at Dusseldorf, in
1880, 70,000 tons of iron or steel railway sleepers in use in Germany.
Mr. Webb, of Crewe, has exhibited a very promising arrangement of
sleepers and fastenings, to be made either of iron or steel. Steel
sleepers should also be used for tramways.
If, now, some clever ironmaster could only accomplish the task of making
a good "street pavement" of cast iron, the increased demand for pig
metal would be enormous. It has nearly been accomplished already, by
several different modes of construction; and there are very many streets
where the luxury of wood pavement, which wears very rapidly, cannot be
afforded, and where macadamizing will not stand the wear and tear of the
heavy traffic. The use of ingot steel, or very mild steel, for making
tin-plates is now an established thing, and manufacturers are now taking
this metal for making large tinned sheets up to seven by three feet.
The making of casks by machinery, cheaper and better than those made by
hand, is now an accomplished fact by Mr. Ransome's machines. There are
twelve factories already established abroad, some turning out 2,000 or
3,000 casks a week. This is a good case of English invention taking the
lead in a manufacture.
Among good mechanical appliances that have been proved to be highly
valuable to the civil engineer may be mentioned the excavating machine,
which answers well for certain soils and situations, though not for all;
and the dredger of Messrs. Bruce & Batho, for excavating from the inside
of piers in water.
In manufacturing chemistry, which, with its numerous mechanical
appliances, is much indebted to mechanical science and engineering,
great advances have been made during the last dozen or twenty years.
Aluminum has been brought into practical use to a large extent, it
being at once a very light metal and a very cleanly one. "Anthracine,"
obtained from coal tar, has been manufactured largely for the purpose of
producing the various brilliant dyes now so common.
New materials for making candles have been manufactured, in some cases
by purely mechanical means, such as boiling together for some hours, at
a pressure of several hundred pounds per square inch, neutral grease and
water, when the water takes up the base, viz., glycerine, and leaves
the grease as an acid grease. This same effect has been noticed in some
steam boilers, where the same water, without admixture of fresh, has
been used over and over again with surface condensers. Then, again,
large rotating chemical furnaces have been introduced; and improved
glass furnaces--particularly tank glass furnaces, in which the batch is
put in at one end, and the working holes are toward the other end--have
cheapened the actual production of glass, and are being worked largely
on the Continent, and to some extent in this neighborhood. Toughened
glass has made some progress for certain purposes. Besides the improved
and extended use of glass in lighthouse illumination, it has again
been pressed into our service for other purposes, through our greatly
extended knowledge of the laws of optics.
Spectrum analysis has become of practical use, and photographs of the
various Fraunhofer lines in the spectrum have been taken as permanent
records of each experiment. That such extended knowledge should have
been developed by that one little instrument, the lens, is but natural;
for the lens is at once the means by which we discover the extreme
magnitude of some portion of the infinite works of the Almighty in the
architecture of the heavens, and by which we appreciate to some extent
the extremely minute markings of a diatom that one cannot see with the
naked eye. At the same time we feel sure that there are other markings
still smaller, as every increase in the power of the microscope has
always rendered visible some markings still smaller than the last;
and in like manner has every increase in the power of the telescope
developed more worlds and suns far away from our system and beyond our
Milky Way. An approach to the infinite in minuteness and to the infinite
in magnitude and distance is thus furnished to us by one instrument
alone.
There was but one further observation that he would venture to make, and
it is this.
When one looks back upon the goodly list of clever men and benefactors
of the human race, who have lived, say, during the last hundred years,
one is sometimes tempted to wish that more of those scientific men, who
have had the most brilliant ideas, and been our greatest discoverers,
should have striven to carry out their discoveries into practice. For
instance, take Faraday's beautiful discoveries in electricity. It was,
in a manner, left to Sir Francis Ronalds, Professor Daniell, Professor
Wheatstone, Fothergill Cooke, Dr. Siemens, and others, to develop from
those discoveries the "intelligence wires," and "bands," that now
encircle the earth, and unite nations, and do so much to prevent
misunderstandings.
It is gratifying to know that the engineering profession has not been
forgotten when honors have been conferred on distinguished men; and
among others may be named Sir William Fairbairn, Sir John Rennie, Sir
Peter Fairbairn, Sir Charles Fox, Sir William Armstrong, Sir Joseph
Whitworth, Sir John Hawkshaw, Sir John Coode, Sir William Thomson, Sir
Joseph Bazalgette, Sir Charles Hartley, Sir Charles Bright, Sir James
Ramsden, Sir John Anderson, Sir George Elliot, Sir Daniel Gooch, Sir
Henry Tyler, Sir Samuel Canning, Sir Edward Reed, and Sir Frederick
Bramwell. With many noble examples before us, and with signs of an
improvement in many branches of commerce, he trusted that the latter
part of the present century will, with somewhat greater exertion of
thought and enterprise on our parts, be marked, not only by numerous
small improvements, but by many substantial inventions for the good of
mankind.
* * * * *
THE HOBOKEN DRAINAGE PROBLEM.
Our thriving neighbor, Hoboken, just across the Hudson River, has a
large and vitally important problem to solve. Of the 720 acres within
the city limits, 270 acres lie at a considerable height above the river
and constitute what are known as the knoll or uplands of Hoboken.
Between this low ridge and Palisade Ridge lie 450 acres of marsh lands
or meadows, 140 acres of which have already been built upon. The marsh
is about half a mile wide, and something like a mile and a half long,
extending southward into Jersey City. The surface is a network of matted
vegetation and roots perhaps five feet deep, and under that lies a mass
of blue clay or river silt 100 feet or more in depth. The original
tidal flow over these marsh lands has been obstructed by viaducts for
railroads and streets, leaving only two natural outlets, a sluice way at
Fifteenth street on the north, and on the south a basin constructed by
the D. L. & W. R. R., 100 feet wide, and 2,300 feet long. The average
level of the marsh land is three feet above mean low water and a foot
and a half below mean high water. In the part built upon the streets are
but two feet above mean high water.
During long easterly and northerly storms, especially at times of high
spring tides, the level of the water in the Hudson is often such as to
cover the meadows even at low tide; and on several occasions the water
at high tide has been 41/2 feet above the level of the meadows, and a foot
or more above the established grade of the streets.
The problem is to drain these marsh lands so as to make them properly
habitable and to protect them from invasion by high tides and storm
waters.
The first drainage map of the district was made about fifteen years ago;
since then over $100,000 have been expended on tidal sewers and other
devices, and several acts have been passed by the New Jersey Legislature
in furtherance of the work. An extended review of the plans proposed
and the experiments made thus far is given in a report presented to the
Board of Health and Vital Statistics, last May, by Engineers Spielmann
and Brush. Ten years ago Mr. Arthur Spielmann, on being directed by the
City Council to prepare plans and estimates for a contemplated sewer in
Ferry street to the western boundary of the city, reported adversely
to the project, believing that such a sewer would fail to answer the
purpose of its construction.
There were but two ways, he thought, of securing the end desired: First,
by raising the grade sufficient to give a good drainage; second, by
making reservoirs and forcing the drainage matter out into the river by
steam pumps. The first method he found impracticable on account of the
cost of filling in so large an area and of raising the large number of
houses already on the low ground. The second plan was recommended as
being much cheaper and entirely practicable. Substantially the same
position is taken in the report of last May, wherein it is alleged that
the superior economy of a pumping system has been sufficiently attested
by several eminent hydraulic engineers who have since investigated the
problems involved. On a small scale the efficacy of the pumping system
has been practically tested, first, in Meadow street, between Ferry and
First streets, and more recently in the southern part of the city, where
a number of property owners have kept twenty-five acres free from water
(except during storms) by means of a private pump.
The comparative economy of the pumping system is shown by estimates
in detail of the cost of constructing and operating such a system in
contrast with, the cost of raising the grade and introducing tidal
sewers. Under both systems the cost of the ordinary sewers will be
about the same. A proper system of tidal sewers, it is claimed, will
necessitate the raising of the grade of the streets on the low lands
to a height at least ten feet above mean high water. The extra cost of
raising the streets is estimated at $3,000,000. The cost of the pumping
system, with machinery and power sufficient to remove all storm water
and sewage, is put at $150,000, while the running expenses, including
interest on the first outlay, are put at $30,000 a year. The interest on
the preliminary expenditure of the first plan considered is $180,000 a
year, or six times as much as the pumping system would involve.
According to the estimates made by Engineer Kirkwood, in his report
of 1874, a total pumping capacity of 134,500,000 gallons a day will
ultimately have to be provided to meet the requirements during the
heaviest storms, besides some six or seven million gallons a day of
sewage proper, exclusive of storm waters. Not more than half that amount
of pumping will be required at first, the increase to be made gradually
as the marsh land is built upon.
* * * * *
ARTISTS' HOMES--No. 14--"BENT'S BROOK."
Our plate illustrates the residence of Mr. J. E. Boehm, A.R.A., the
sculptor. Bent's Brook is situated at Holmwood, not far south of
Dorking, on the Mid-Sussex line, and commands some fine views of
well-timbered country. The site itself is comparatively low, and the
soil being clay it was advisable to keep the building well out of the
ground, and in this way a rather unusually high elevation for such
a house was obtained. The plan is very compactly arranged, with an
ingenious approach to the well-centered hall and staircase, over
which, by a mezzanine contrivance, a good store place is secured. The
drawing-room has a belvedere bay, reached from the garden by an external
stair, under which is a covered garden seat. A balcony overlooking the
garden leads also from the drawing-room, and a billiard room is arranged
on the basement level with a separate entrance from the porch. A
tradesmen's entrance is provided elsewhere. The kitchen and offices are
on the lower floor level, and a kitchen yard is conveniently placed at
the rear. Red brick, with cut-brick dressings, is the material used
throughout for the walls, the upper parts of which are hung with
ornamental tiles. The gables are enriched with wide, massive barge
boards, and the roof is surmounted with a white wooden cupola over the
principal staircase. The terracotta panels along the entrance front,
over the principal floor windows, were designed by Mr. Boehm himself.
The work was executed by Mr. H. Batchelor, builder, of Betchworth, and
the architect of the house was Mr. R. W. Edis, F.S.A., who superintended
its erection.--_Building News_.
[Illustration: ARTISTS' HOMES No. 14 "BENT'S BROOK."]
* * * * *
ON SOME RECENT IMPROVEMENTS IN LEAD PROCESSES.
[Footnote: Lately read before the Institute of Mechanical Engineers.]
By NORMAN C. COOKSON, of Newcastle.
The author began by stating that probably in few trades have a smaller
number of changes been made during recent years, in the processes
employed, than in that of lead smelting and manufacturing. He then
briefly noted what these changes are, and went on to describe the "steam
desilverizing process," as used in the works of the writer's firm, and
in other works licensed by them, which process is the invention of
Messrs. Luce Fils et Rozan, of Marseilles. It is one which should
commend itself especially to engineers, as in it mechanical means
are employed, instead of the large amount of hand-labor used in the
Pattinson process. It consists in using two pots only, of which the
lower is placed at such a height that the bottom of it is about 12
in. to 15 in. above the floor level, while the upper is placed at a
sufficiently high level to enable the lead to be run out of it into
the lower pot. The capacity of the lower pot, in those most recently
erected, is thirty-six tons--double that of the upper one. Round each
pot is placed a platform, on which the workmen--of which there are two
only to each apparatus--stand when skimming, slicing, and charging the
pots. The upper pot is open at the top, but the lower one has a cover,
with hinged doors; and from the top of the cover a funnel is carried
to a set of condensers. At a convenient distance from the two pots is
placed a steam or hydraulic crane, so arranged that it can plumb each
pot, and also the large moulds which are placed at either side of the
lower pot. The mode of working is as follows:
The silver lead is charged into the upper pot by means of the crane.
When melted, the dross is removed, and the lead run into the lower, or
working pot, among the crystals remaining from a previous operation.
When the whole charge is thoroughly melted, it is again drossed; and in
order to keep the lead in a thoroughly uniform condition, and prevent it
setting solid on the top and the outside, a jet of steam is introduced.
To enable this steam to rise regularly in the working pot, a disk-plate
is placed above the nozzle, which acts as a baffle-plate; and uniform
distribution of the steam is the result. To quicken the formation of
crystals, and thus hasten the operation, small jets of water are allowed
to play on the surface of the lead.
This, it might be thought, would make the lead set hard on the surface;
but the violent action of the steam acts in the most effectual manner
in causing the regular formation of crystals. Owing to the ebullition
caused by this action of the steam, small quantities of lead are forced
up, and set on the upper edges and cover of the pot. From time to time
the valve controlling the thin stream of water playing on the top of the
charge is closed, and the workman, opening the doors of the cover in
rotation, breaks off this solidified lead, which falls among the rest of
the charge, and instantly becomes uniformly mixed with it.
Very little practice enables an ordinary workman to judge when
two-thirds of the contents of the big pot are in crystals, and one-third
liquid; and when he sees this to be the case, instead of ladling out the
crystals ladleful by ladleful, as in the old Pattinson process, he taps
out the liquid lead by means of two pipes, controlled by valves, the
crystals being retained in the pot by means of perforated plates.
The liquid lead is run into large cone-shaped moulds on either side of
the pot; and a wrought iron ring being cast into the blocks thus formed,
they are readily lifted, when set, by the crane. To give some idea of
the rapidity of the process, it may be mentioned that from the time the
lead is melted and fit to work in the big pot, to the time that it is
crystallized and ready for tapping, is, in the case of a 36 ton pot,
from thirty-five to forty-five minutes; and the time required for
tapping the liquid lead into the large moulds is about eight minutes.
Before the lead begins to crystallize, the upper pot is charged with
lead of half the richness of that in the lower pot. Thus, when the
liquid lead has been tapped out of the lower pot, it is replaced by a
similar amount of lead of the same richness as the remaining crystals,
by simply tapping the upper or melting pot, and allowing the contents to
run among the crystals.
The same operation is repeated from time to time, until the crystals are
so poor in silver that they are fit to be melted, and run into pigs for
market.
The large blocks of partially worked lead are placed by the crane in
a semicircle round it, and pass successively through the subsequent
operations. The advantages of the steam process, as compared to the old
six-ton Pattinson pots formerly used by the writer's firm, are: (1) a
saving of two-thirds amount of fuel used; (2) the saving of cost of
calcination of the lead to the extent of at least four-fifths of
all that is used; (3) above all, a saving in labor to the extent of
two-thirds. The process has its disadvantages, and these are a larger
original outlay for plant, and a constant expense in renewals and
repairs. This is principally caused by the breakage of pots; but with
increased experience this item has been very much reduced during the
last two or three years.
The "zinc process" of desilverizing, which is largely used by Messrs.
Locke, Blackett & Co., and was patented in the form adopted by them
about fourteen years since. The action of this process is dependent on
the affinity of zinc for silver. The following is a brief description of
it:
A charge of silver lead, usually about fifteen tons, is heated to a
point considerably above that which is used in either the Pattinson or
the steam process. The quantity of zinc added is regulated by the amount
of silver contained in the lead; but for lead containing 50 oz. to the
ton, the quantity of zinc used is in most cases about 11/2 per cent, of
the charge of lead. The lead being melted as described, a portion of
this zinc, usually about half of the total quantity required for the
charge, is added to the melted lead, and thoroughly mixed with it by
continued stirring. The lead is now allowed to cool, when the zinc is
seen gradually to rise to the top, having incorporated with it a large
proportion of the silver. The setting point of zinc being above that
of lead, a zinc crust is gradually formed, and this is broken up and
carefully lifted off into a small pot conveniently placed, care being
taken to let as much lead drain off as possible. The fire is again
applied strongly to the pot, and when the lead is sufficiently heated, a
further quantity of zinc, about one-third of the whole quantity used, is
added, when the same process of cooling and removing the zinc crust is
repeated. This operation is gone through a third time with the remaining
portion--1/4 per cent.--of zinc; and if each of these operations has
been carefully carried out, the lead will be found to be completely
desilverized, and will only show a very small trace of zinc. In some
works this trace of zinc is allowed to remain in the market lead, but
at Messrs. Locke, Blackett & Co.'s works it is invariably removed by
subjecting the lead to a high heat in a calcining furnace. The zinc
crusts, rich in silver, are freed as far as possible from the lead by
allowing this to sweat out in the small pot, after which the crusts are
placed in a covered crucible, where the zinc is distilled off, and a
portion of it recovered. The lead remaining, which is extremely rich in
silver, is then taken to the refinery, and treated in the usual manner.
The writer is given to understand that the quantity of zinc recovered is
as high as from 50 to 60 per cent. of the total quantity used.
Although it was said that the rolling or milling of lead remains
unchanged in its main features since the first mill was established, yet
the writer's firm have introduced many important improvements. When lead
is required for sheet making, instead of running out the market lead
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