Scientific American Supplement, No. 430, March 29, 1884
by
Various
Part 2 out of 2
The workman runs the four cadinhes at once, this being easily enough
done, since he has neither to bother himself with regulating the wind,
which enters always with the same pressure, nor with the flow of the
scoriae, which remain always at the bottom of the crucible. His role
consists simply in keeping his fires running properly, being guided in
this by the color of the flame without making an examination in the
interior. He draws each of the four blooms out from its bed at the end
of the operation, while the assistant carries the first to the hammer
and the three others to the reheating furnace. He afterward cleans
out the crucible, prepares the bed of sand and charcoal, fills with
charcoal, and then passes to the next, and so on.
[Illustration: FIG. 5.--REHEATING FURNACE.]
_Trip Hammer_.--The workman at the hammer takes the bloom from the hands
of the assistant and shingles it under the head. Then he begins to give
it shape, bringing it to the state shown at c, in Fig. 7. The assistant
then brings him another bloom and takes the one that has been shingled
to the reheating furnace, where he heats but one of its extremities.
When the four blooms have been shingled, the workman takes up the first
and begins to draw out one of its extremities, which he afterward cools
in water and uses as a handle for finishing the work, d. Then he reheats
the other extremity, and, after drawing it out as he did the other,
obtains a bar of finished iron which he doubles, as shown at e, to thus
deliver to the trade.
[Illustration: FIG. 6.--CADINHE IN OPERATION.]
One of these bars weighs from 11 to 12 kilogrammes. It will be seen
that, during the course of the work, the furnace workmen and the hammer
workmen have well defined duties to perform; but it is not the same with
the assistant, who goes from one to the other according to requirements.
There are, however, some forges in which each of the workmen has an
assistant, since the blooms produced are heavier, and one assistant
would not suffice for the work of the two men. In such a case the
assistant at the crucibles carries the blooms to the reheating furnace,
and the assistant at the hammer carries them from thence to the hammer.
[Illustration: FIG. 7.--WORKING THE BLOOM.]
ELABORATION OF THE ORE.
We have seen that the workman who has charge of the fire contents
himself with putting charcoal and ore alternately into the crucibles,
and that too according to the aspect of the flames, without making any
examination in the interior, in order to judge whether the work is
proceeding well. The bloom forms gradually beneath the nozzle of the
tuyere, in the center of the bed of sand and charcoal, and is surrounded
on every side with an exceedingly pasty mass, formed of silicates of
iron and manganese (Fig. 7). It is only at the end of the operation that
the workman, by means of a rod, causes the burning coal to drop and
verifies the proper position of the bloom by breaking the layer of
scoriae that surrounds it. This coating he breaks off, removes the bloom
with a hook, and agglutinates with his rod the different bubbles that it
exhibits, and the assistant then carries it to the hammer.
SETTING UP A FORGE.--SELLING PRICE OF THE IRON.
To set up a forge like the one we have described, it is necessary to
count upon a first cost of about 10,000 francs. Add to this the cost of
50 hectares of forest to furnish the charcoal that the workmen have to
make every day. The cost of this is very variable, and floats between
2,500 and 5,000 francs per 100 hectares. The cost the ore is only that
connected with getting it but and hauling it.
_Manual Labor_.--The charcoal burners receive 1.25 francs per load of 90
kilos, thus bringing the price of the product (including cost price of
forest) at 2.4 francs per 100 kilos. The workmen in the furnace are paid
at the rate of from 2.50 to 3.75 francs per day. Those that work the
hammers receive 3.75 francs, and the assistants 1.25 francs.
_Carriage of the Forged Iron_.--The iron is carried from the forge
to the places of consumption on the backs of mules, and the cost of
carriage is, on an average, 0.25 franc per 100 kilos and per kilometer.
_Selling Price_.--The selling price is very variable, and depends
principally upon the distance of the place where sold from the different
forges that surround it. At Ouro Preto the price varies between 45 and
50 francs per 100 kilos.
The following is a _resume_ of the data which precede:
Cost of first establishment.................. 10,000 fr.
Charcoal per kilogramme...................... 2.40
{ Furnace men.... 2.50 to 3.75
Manual labor per day { Hammer men............. 3.75
{ Assistants............. 1.25
Carriage of forged iron per kilometric ton..... 2.50
Selling price per 100 kilos................ 45 to 50
--_Le Genie Civil_.
* * * * *
THE STEAMER CHURCHILL.
We give engravings of the Churchill, a vessel lately built to the order
of Mr. Walter Peace, London agent to the Natal Harbor Board, by Messrs.
Hall, Russell, and Co., Aberdeen. She was designed by Mr. J.F. Flannery,
consulting engineer to the Board, for special service at Natal. The
Churchill has been constructed so as to be capable of towing into or out
of harbor over the bar in any weather, of acting as a very powerful fire
engine, of carrying a large amount of fresh water for the use of other
ships, of landing troops from transports which the harbor is too shallow
to admit, of recovering lost anchors and cables, of which there are a
large number off the coast, and of acting in time of need as a torpedo
or coast defense vessel; she was launched on the 16th August, and is
likely to fulfill all these requirements.
[Illustration: THE NEW STEAMSHIP CHURCHILL.]
The principal dimensions of the vessel are: Length between
perpendiculars 115 feet, breadth, extreme, 22 feet, depth of hold 11
feet, and maximum draught with full bunkers 7 feet 6 inches. There are
four water-tight iron bulkheads forming five compartments; the stern is
built very full to protect the propellers. Accommodation is arranged on
deck for the captain aft with two spare berths, mate and two engineers
amidships, while six white hands will occupy the forward forecastle, and
six Kaffirs the after one. For towing purposes she is fitted with one
main and two skip hooks secured to the main framing; towing rails are
placed aft, while bitts are put on one each quarter, will be seen by
referring to the deck plan.
The vessel is propelled by twin screws 6 feet 8 inches in diameter and
13 feet 6 inches pitch; these are of cast iron, have four blades, and
are driven by a double pair of compound inverted direct acting engines
(see Figs. 4 to 7) which are capable of developing 600 indicated horse
power, and whose cylinders are 19 inches and 34 inches in diameter with
a stroke of 2 feet. The condensers form part of the engine frame, and
have guide faces cast on for the crosshead shoes. They are fitted with
gun metal tube-plates, and each contain 516 tubes, 3/4 inch in diameter,
which have an exposed length of 6 feet 5 inches, and give a total
cooling surface of 650 square feet. The air and circulating pumps are
bolted to the back of the condensers, and are worked by levers from the
engine crosshead. Each engine has one feed and one bilge pump attached
to the air pump, and worked by the same lever. The plan of the engines
shows the pump arrangement very completely.
[Illustration: ENGINES AND BOILERS OF THE NEW STEAMSHIP CHURCHILL.]
The steam is supplied by two circular return tube boilers, 9 feet 6
inches in diameter and 10 feet long, with two furnaces in each. The
boilers, which are of steel throughout, except the tubes, are placed
longitudinally, and are fitted with two pairs of the Martyn-Roberts
patent safety valves. They have one steam dome between them. The total
heating surface is 1,700 square feet, the total steam space is 330 cubic
feet, and the working pressure 100 lb. per square inch.
The fire pump is a Wilson's "Excelsior," with 10 inch steam cylinder and
8 inch water barrel. This powerful pump is in a special compartment of
the fore hold, and will draw water from the bilge, sea, or either hold.
A steam windlass and a double-handle winch are on deck as shown. On
trial trip the engines of the Churchill indicated a maximum of 645.5
horse power, driving the vessel 10.495 knots per hour. The vessel is
remarkable for diversity of uses, for heavy engine power in a small
hull, and for general compactness of arrangement.--_Engineering_.
* * * * *
THREE-WAY TUNNELS.
Mr. T.R. Cramton, who at the Southampton meeting of the British
Association suggested a method of tunneling which, under certain
conditions, seems of excellent promise, brought forward a suggestion at
Southport for the construction of three-way tunnels. Now, the undoubted
aim of all engineers is economy of construction and the securing of
permanent advantages. Mr. Crampton maintains that the suggested system
will give these, that three tunnels of, say, 17 ft. diameter, can be
constructed cheaper than one of 30 ft. diameter. After describing Sir J.
C. Hawkshaw's scheme for the ventilation of long tunnels, the three-way
scheme was discussed. Three separate tunnels of 17 ft. diameter each,
or 227 ft. area, are to be connected by large passages about midway
of their length. These passages are without valves; in fact, free air
passages. Between these midway connections and the ends, say again
midway between, is formed a branch at right angles either above or below
with separate openings from the branch into the other tunnels, such
openings being provided with doors or valves quite clear of the main
tunnel, any two of which may be closed, thus separating at this point
the corresponding tunnels from the third. The branch is to be led to any
convenient position where the exhustion apparatus can be placed. If two
of the tunnels are left open to this branch, and the third one shut off
from it by closing the doors, the vitiated air will be drawn from the
two working tunnels, through the connecting branch, while fresh air will
be partly sucked down the vertical shafts through their open ends and
partly at the center tunnel, which is supplied by forcing air down the
vertical shaft in communication with it, a stop or door being placed
just outside of the bottom of the shaft so as to compel the air to flow
to the center of the tunnel. It will be observed that no trains are
running in this air tunnel so long as it is so used; there are similar
doors for the working tunnel, but they are kept open, unless either of
them is required to be made into an air tunnel, so that the passing
trains run no risk of running into the doors. By means of the doors
above mentioned, any one of the three tunnels can be used as a fresh-air
tunnel, in which the men doing the repairs to the road would be clear of
the traffic, while the other two are used for the traffic, as well as
outlets for the mixed impure gas and air. If a breakdown of a train
occurs in any one tunnel, that tunnel can at once be converted into a
fresh-air one, while its traffic is transferred to the one previously
used for air, thereby avoiding delay. The system described for splitting
the air and drawing off the noxious gases is very similar to that
described by Mr. Hawkshaw at Southampton. The valves and other details
being added, to make the system applicable to three tunnels, it will
be obvious that other modes of ventilation may be adopted. In order to
reduce the number of men working in the tunnel it is proposed, if found
practicable, not to adopt the ordinary ballast and cross sleepers, but
to substitute the longitudinal timber system, the timbers to be secured
to brickwork or concrete, forming a part of the tunnel lining, placing
efficient elastic material between the foundation and longitudinals for
their whole area, also between the rails and sleepers. An open drain is
formed between the rails; by this plan any water accumulating flows over
smooth surfaces through small channels into a drain, the tunnel on each
side being dry. The saving of labor in repairs, if this system can be
employed, is so evident that a large amount of money might be expended
in endeavoring to discover a suitable elastic material for the purpose.
There are data on many long viaducts sufficient to justify experiments
being made on the subject, and it is not unreasonable to expect that
suitable material may be met with. In very long tunnels nothing should
be omitted tending to reduce the number of men working in them. The
opinion was expressed that in tunnels passing through solid materials,
and proper foundations being made for the longitudinals to rest upon,
with good elastic material placed between the rails and sleepers and
foundations, one-half of the men employed on the ordinary cross sleeper
road resting on ballast would be saved, more particularly as the repairs
are effected in pure air free from the traffic as explained. The
estimate as to the cost of this system was upon the dimensions given by
Sir J. Hawkshaw, and the following gives the comparison:
The quantity of excavation and brickwork or concrete in each case will
be as follows: Single tunnel: 30 ft. diameter lining, 3 ft. thick, with
the brickwork forming the air passage = to 36.5 cubic yards per yard
forward. Excavation to outside of brickwork 36 ft. diameter = to 113
cubic yards per yard forward. Three tunnels 17 ft. diameter and 18 in.
brickwork. Brickwork lining for three tunnels = 24.5 cubic yards per
yard forward. Excavation outside brickwork for the same 105 cubic yards
per yard forward. It is assumed that three 17 ft. tunnels are stronger,
more conveniently formed, and involve less risks in construction than
one of 30 ft. diameter; at the same time there is no difficulty in
making the latter. The above shows the saving in the three tunnels of
23 per cent. in brickwork, and about 7 per cent. of earthwork, compared
with one of 30 ft. With regard to ventilation, it is well known that the
power required to force air along passages is practically as the cube of
the velocity; and as the area of the air passages in the single tunnel
is 106 ft. with speed ten miles per hour, and that of one of the 17 ft.
diameter is 227 ft., or rather more than double, giving only five miles
per hour velocity, it follows that the power for this portion would be
eight times less. That for the working tunnels would be practically the
same, the velocities being nearly alike in both cases, which would be
about 21/2 miles per hour--the 30 ft. having an area of 470 ft., the
two single ones together about 450 ft. Upon the face of it the system
deserves a trial. A full consideration of the scheme by engineers
preparing plans for new tunnels would no doubt throw further light
upon the subject and be of interest wherever such work is
contemplated.--_Contract Journal_.
* * * * *
MONT ST. MICHEL.
Every one who has the slightest regard for historical monuments, who
values mediaeval architecture, or cares in the least degree for the
beautiful and the picturesque, must heartily sympathize with M. Victor
Hugo in his protest against the proposed scheme for uniting the
wonderful island of Mont St. Michel with the mainland by means of a
_causeway_, and possibly a _railway_!
Those who know Mont St. Michel well, and, like the writer, have spent
several days upon the island, cannot but feel that such a scheme would
not only be a frightful disfigurement, but would entirely destroy all
the associations and the poetry of the place. Practical people will
say, "Modern improvement cannot stop in its march forward to consider
poetical associations and mere artistic whims and fancies." Now, this
would be a possible argument if Mont St. Michel were a busy, thriving
town, a commercial port, or the seat of great industries; but in a case
where the only trade is that of touting, the only visitors sightseers,
the only "stock-in-trade" mediaeval remains, surely, from a practical
point of view, anything which will injure these antiquities will really
destroy the importance of the island, as its _only_ value consists in
its wonderful historic and artistic associations.
[Illustration: MONT ST. MICHEL, NORMANDY.]
The first glimpse of Mont St. Michel is strange and weird in the
extreme. A vast ghostlike object of a very pale pinkish hue suddenly
rises out of the bay, and one's first impression is that one has been
reading the "Arabian Nights," and that here is one of those fairy
palaces which will fly off, or gradually fade away, or sink bodily
through the water. Its solemn isolation, its unearthly color, and its
flamelike outline fill the mind with astonishment.
Mont St. Michel is by far the most perfect example of a mediaeval
fortified abbey in existence, with its surrounding town and
dependencies, all quite perfect; just, in fact, as if time had stood
still with them since the fifteenth century. The great granite rock
rises to the height of two hundred and thirty feet out of the bay; it
is twice an island and twice a peninsula in the course of twenty-four
hours. The only approach is at low water, by driving or walking across
the sands. When, however, one arrives within a few yards of the solitary
gate to the "town," walking or driving has to be abandoned, and here
the commercial industries of the inhabitants commence. A number of
individuals, half sailors and half fishermen, are standing ready to
carry you on their shoulders over the small gully, which is very rarely
quite dry. Entering through the old gate one sees two ancient pieces
of cannon taken from the English, who unsuccessfully laid siege to the
place in 1422. Close to the gate are the two rival inns, which are very
primitive in their arrangement, the entrance hall forming the kitchen,
as in many old Breton houses. A second frowning old gateway leads to the
single street, which, passing between two rows of antique gabled houses,
and under the chancel of the little parish church, conducts one to the
almost interminable flight of stone steps leading to the gateway of
the monastery. Upon ringing the bell a polite lay brother opens the
iron-studded door, and we are admitted into a solemn, vaulted hall, with
another stone staircase opposite. Here we go up and up, to a second
vaulted hall, where, in olden times, we should have had to give up any
arms which we were carrying. Then another stone staircase, which lands
us in a small court with a well in it, at the opposite end of which is a
heavy and solid arched doorway. We pass through this, expecting to find
ourselves on the top of the central tower of the church at least, and
are surprised to find ourselves in the solemn and almost dark crypt of
the church. Here we have climbed up some 230 feet above the world and
the sea to find ourselves in an underground vault; up in the air and
down under the rock at the same time. Wonderfully beautiful is this
strange crypt, when one's eye gets accustomed to the gloom, with its
exquisite ribbed and vaulted roof, supported upon huge circular columns.
Returning to the court, another doorway conducts us into a most superb
Gothic hall, with a row of slender columns down the center. This was the
monks' refectory in ancient times; adjoining this is another grand hall,
divided into four aisles by rows of granite columns, all of the most
perfect thirteenth century work. Above these are two other halls, still
more magnificent than those below. One of these, called the "Salle des
Chevaliers," is probably the most beautiful Gothic hall in existence.
Again a flight of stone stairs, and we find ourselves, where we should
certainly not have expected, in the cloisters of the monastery, the
exquisite architecture of which, with its countless marble columns and
delicate double arcades, cannot be described.
The church deserves a few words, as it is a veritable cathedral as to
size and grandeur. The choir is immensely lofty, and constructed of
granite most elaborately wrought in the later Gothic or flamboyant
style. The nave and transepts are in the old Romanesque style, with
solid pillars and low round arches. The church is beautifully kept, and
contains some very interesting old reredoses and altars with carving in
alabaster. The one modern altar in the Lady Chapel is composed entirely
of silver! Our space will not permit us to describe the numerous
interesting old Abbey buildings--the library, the prior's lodging, the
vast kitchen, the prisons, the dungeons, and the means of supplying the
place in times of siege. The proposed causeway would join the island to
the left of our view, and our readers can imagine the abominable effect
of a high embankment disfiguring this point, and breaking through the
interesting old walls and towers, with, perhaps, a Brummagem Gothic
station against the old time-worn gateway.--_H. W. Brewer, in London
Graphic_.
* * * * *
ADORNMENTS OF THE NEW POST OFFICE AT LEIPZIG.
The cuts given herewith, taken from the _Illustrirte Zeitung_, represent
two statues for the new Post Office at Leipzig. The sculptor, Kaffsack,
has represented the post and the telegraph as winged female figures. The
figure representing Mail holds a horn or trumpet in her left hand, and
a letter in her right hand. The figure representing Telegraphy holds a
bunch of thunderbolts in her left hand, and unrolls a band for receiving
dispatches with her right hand. It will be observed that the figure
representing Telegraphy is made much lighter and more graceful than the
figure representing Mail, and has also a more energetic expression of
countenance, thus indicating the greater speed of Telegraphy.
[Illustration: ADORNMENTS OF THE NEW POST OFFICE, LEIPZIG, GERMANY.]
* * * * *
COAL GAS AS A LABOR-SAVING AGENT IN MECHANICAL TRADES.
By THOMAS FLETCHER, F.C.S.
Gas, as a fuel, is an absolute necessity to the economical carrying out
of many commercial processes. It is often used in the crudest and most
costly way; a burner may be perfect for one purpose, yet exceedingly
wasteful for another, and however good it may be, an error of judgment
in its application may lead to its total condemnation. An excess of
chimney draught, in cases where a flue is necessary, may pull in
sufficient excess of cold air to almost neutralize the whole power of
the burner, unless a damper is used with judgment. With solid fuel, an
excess of draught causes more fuel to be burnt, but with gas the fuel
is adjusted and limited; there is no margin or store of fuel ready to
combine with the excess of air, which, therefore, lowers the amount
of work done by its cooling power. The power of any burner, for any
specified purpose, depends not only on its perfection, but to a far
greater extent on the difference in the temperature of the flame and of
the object to be heated. For instance, if a bright red heat is required,
it is not possible to obtain this temperature economically with any
burner working without an artificial blast of air; the difference
between the temperature of the flame and that of the object heated is
too little to enable the heat to be taken up freely or quickly, and
the result is a large loss of costly fuel. If we want to obtain high
temperatures economically, an artificial blast of air is necessary,
and the heavier the pressure of air, the greater the economy. On the
contrary, low temperatures and diffused heat are obtained best by flames
without any artificial air supply.
For such purposes as ovens, disinfecting chambers, japanners' stoves,
founders' core drying, and similar requirements the best results are
obtained by a number of separate jets of flame at the lowest part of the
inclosed space, and the use of either illuminating or blue flames is a
matter of no importance, as the total amount of heated air from either
character of flame is the same. If there is any preference, it may be
given to illuminating flames, as the proportion of radiant heat is
greater, and this makes the average temperature of the inclosed space
more equal; but on the other hand, may be considered the greater
liability of the very fine holes, necessary for illuminating flames, to
be choked with dust and dirt. This may, to a great exent, be obviated
by using very small union jets, and setting them horizontally, so as
to make a flat horizontal sheet of flame. Burners placed this way are
practically safe from the interference of falling dust or dirt, but not
from splashes. Falling dirt or splashes must always be considered in the
arrangement of any burners, and the ventilation must be no greater than
is absolutely necessary for the required work. In cooking, this limit
of ventilation may be exceeded, as most things are better cooked with a
free ventilation, the extra cost of fuel being well compensated for by
the better quality of the result.
The air in an oven or inclosed space heated by flames inside is similar
in character to highly superheated steam. It contains a large proportion
of moisture, and yet has the power of drying any substance which is
heated to near its own temperature. A mass of cold metal placed in
the oven is instantly bedewed with moisture, which dries up as the
temperature of the metal rises. This is, for many purposes, an
objection, and the remedy is to close the bottom of the oven and place
burners underneath. If for drying purposes and a current of air is
necessary, the simplest way is to place in the bottom of oven the a
number of tubes hanging downward in such a position that the heat of the
flame acts both on the bottom of the oven and the sides of the tubes,
which, of course, must be long enough for the lower opening to be well
below the level of the flame. The exit may be at any level, but for
drying purposes it is better at the top, and it should be controlled
by a damper to prevent cooling by excessive currents of air. If not
otherwise objectionable, the arrangement of flames inside the oven is
far the most economical in use.
Where an oven or drying chamber is used continuously, it should be
jacketed with slag wool or boiler composition, but for many purposes
this is no advantage. As an example both ways, I will instance the
drying of founders' cores where there is only one blow per day. The
cores of an ordinary foundry can be dried by gas in a common sheet iron
even in about half an hour; any accumulation of heat after that time
would be useless, and a jacketed oven would be of no advantage.
For the disinfection of clothes in vagrant wards and hospitals for
infectious diseases, on the contrary, a continued heat is necessary, and
in this case the accumulation of reserve heat, which takes place slowly
in a jacketed oven, becomes of value, as the gas can be turned low or
out, and the ventilators closed, insuring a more complete disinfection
with a much smaller gas consumption. Where an oven or heated chamber is
much used for periods of over half an hour at once, a non-conducting
casing pays well by reduced gas consumption.
For albumen and glue drying, leather enameling, tobacco drying, and
purposes where a large space has to be very slightly and equally warmed
when the weather is unfavorable, steam-pipes are generally used, but,
not being always available, an exceedingly good arrangement may be made
by placing at intervals in the room gas burners, of any construction,
close to the floor, and surrounded with a sheet-iron cylinder, say 2 ft.
or 3 ft. high. The top of these cylinders must be connected throughout
with a fairly large flue, which will take the products of combustion
from the whole, and this flue must be carried either horizontally, or
with a slight rise, so as to utilize all the waste heat. The reason for
having a number of stoves at intervals is that the heat in a flue will
not carry, for any useful purpose, more than about 8 ft. or 10 ft., and
a single stove would give an irregular temperature in any except a very
small room. If all are not used at once, the flues of those not in use
may be closed by a damper to prevent down draught. The use of hot water
pipes heated by gas may also be occasionally advisable, but, unless for
some special reason, it is much more economical to use coal or coke, as
the bulk of water makes an exceedingly good regulator, and makes a fire
practically as steady and reliable as gas, thus superseding the more
costly fuel.
For one of my own purposes I need hot-water pipes, having very little
variation in temperature night and day; and using coke for economy's
sake, I get a regular temperature by heating a large quantity of water,
about 200 gallons, with the fire, and inclosing this in a tank jacketed
with slag wool. My circulating pipes run from this tank, and a
practically steady temperature, night and day, can be obtained with the
most irregular firing, and occasional extinction of the fire for several
hours at once.
For the heating of liquids, the greatest economy is to be obtained
from one single flame, of as high a temperature as can conveniently be
obtained, and the flame must be in actual contact with the vessel to be
heated. In jacketing vessels, to prevent draughts, care must be taken
that the jackets do not cause currents of cold air to rise rapidly up
the sides of the vessel, and so cool it. If this is the case, the use of
a jacket, instead of being an economy, is a positive expense, and waste
of heat. Many processes, such as making oil and turpentine varnishes,
require a heat under instant control, and in these the use of gas is an
important matter, as the loss and risk of fire are very serious elements
of expense, more especially in small works where special and costly
preparations for contingencies cannot be afforded. I have here a burner
which, for its power, is, perhaps, the most compact and gives the
highest temperature of any burner yet known, and it is easily made in
almost any size; it has, I think, many special advantages. The use of
gauze, which is its only weak point, is more than compensated for by the
very high duties obtained in practice with it, owing to the compactness
and concentration of the heat obtained. The following extract from my
communication to the Gas Institute will give all particulars as to the
constructive detail of this burner. Those who wish to go further into
the matter will find the paper referred to in the publication of the
Gas Institute for the current year, and also in the _Journal of Gas
Lighting_, June 26, 1883, and the _Review of Gas and Water Engineering_,
June 16, 1883.
"The first and most important part is the mixing chamber or tube, one
end of which is supplied separately with gas and air, which at the other
end are, or should be, delivered as a perfect mixture. It may be taken
as a rule that this tube, if horizontal, should not be less in length
than four and a half times or more than six times its diameter. It is
a common practice to diminish or make conical-shaped tubes. All my
experience goes to prove that, excepting a very trifling allowance for
friction, the area of the smallest part of the tube rules the power, the
value of the mixing-tube being no more than that of the smallest part.
If the mixing-tube is upright, new sources of interference comes in;
notably the varying specific gravity of the mixture. Except with one
definite gas supply, the result is always more or less imperfect, and
regular proportions cannot be obtained. This is now so well known that
the upright form has been practically discarded for many years, and
is now only used where the peculiar necessities of the case give some
special advantage.
[Illustration: Fig. 1. SPECIAL HIGH POWER BURNER. SHEWING ATTACHMENT B
WHEN USED WITH A BLAST OF AIR]
"The diameter of the mixing tube is a matter of importance, as it
rules the quantity of gas which can be satisfactorily burnt in any
arrangement. With large flames, given a certain size of gas-jet, the
diameter of the mixing-tube should be not less than ten times as great.
For instance, at 1 inch pressure, a jet having a bore of 1/8 inch will
pass about 20 cubic feet of gas per hour. To burn this quantity of gas,
a mixing tube is necessary 10/8 or 11/4 inch in diameter. By the first
rule this tube must be in length equal to four and a half times its
diameter, or 5-5/8 inches. It would appear that the mixing-tube, having
100 times the area of the gas jet, is out of all proportion to the size
necessary for obtaining a mixture of one of gas to nine or ten of air;
but it must be remembered that the gas is supplied under pressure. It is
therefore evident that no mere calculation of areas can be taken,
into account, unless the difference in pressure of the supply is also
considered. A complete reversal of this law is shown in that ruling the
construction of blowpipes, which I have already given in a previous
paper on 'The Use and Construction of the Blowpipe.' In these the air
supply, being under a heavier pressure, is much smaller in area than
the gas inlet; and, to obtain maximum power, the air-jet requires to be
enlarged in proportion to the gas pressure.
"Given a certain area of tube delivering a combustible mixture, the
outlet for this mixture must be neither more nor less than the size of
the tube. Taking an ordinary drilled tube, such as is commonly made, and
of the dimensions before given--i. e., 11/4 inch bore--if the holes are
drilled 1/8 inch in diameter the tube will supply 10 x 10 = 100 of these
holes. In practice this rule may be modified.
"The variations from the rule, however, must be a matter of experience
with each form of burner. There is also the fact that with small divided
flames it is not necessary to mix so large a proportion of air, as each
flame will take up air, on its external surface; but in this case the
flames are longer, hollow, and of lower temperature. As a matter of
actual practice, where a burner is used which gives a number of flames
or jets, the diameter of the mixing-tube does not need to exceed eight
times the diameter of the gas jet; the remainder of the air required
being taken up by the surfaces of the flames.
"Wire gauze, made of wire the thickness of 22 iron wire gauge, 20 wires
to the linear inch, and tinned after weaving, has an area in the holes
of 1/4 its surface. By calculation, the area of a gauze surface in a
burner should, therefore, be taken at four times that of the tube, and
our standard of 11/4 inch tube requires a gauze surface of 21/2 inches in
diameter. This rule is subject to variation in burners of a small size,
owing to the air that can, if required, be taken up by the external
surface of the flame, which, of course, is much greater in proportion in
a small flame than in a large one. Where the diameter of the gauze is,
say, not over one or two inches, the theoretical maximum gas supply may
be exceeded, and a varying compensation is necessary with each size.
My rule is intended to apply to burners of larger diameters, where the
external air supply plays a comparatively unimportant part.
[Illustration: Fig. 2.]
"It must be remembered that burners of this class, which burn without
the necessity of an external air supply in a flame which is solid,
require the mixture to be correct in proportions. A very slight
variation makes an imperfect flame. Not only does the gas jet require
to be adjusted with great precision, but it also needs more or less
adjustment for different qualities of gas. An ordinary hollow or divided
flame is able to take up on its surface any deficiency of air supply;
but with the high power solid flames the outside surface is small, and
the consequence is that one of these burners, adjusted for gas of poor
quality, may, when used with rich gas, give a long hollow or smoky
flame, unless the gas jet be reduced in size. When perfect, the flame
shows a film of green on the surface of the gauze; and if a richer gas
is used, the green film lifts away. To cause this to fall again, and to
produce a solid flame, it is necessary to take out the gas jet, and
tap the end with a hammer until, on trial, it is found correct. If too
small, the green film lies so closely as to make the gauze red hot.
Where the 'tailing up' of the carbonic oxide flame is objectionable,
there is no practical difficulty whatever in constructing these burners
as a ring, with an air supply in the center, which greatly reduces the
length of the 'tail.' In practice it is a decided advantage to have a
center air-way in all burners of more than about 2 in. diameter, as it
enables the injecting tube to be slightly shortened, and lessens the
liability of the green film to lift with varying qualities of gas. In
this class of burner I have adopted the small central air-way as a
decided improvement in the burners."
In such processes as the roasting of coffee, chiccory, grain, etc., a
diffused heat is necessary, but of much greater intensity than can be
obtained with economy from heated air. In these cases the application of
a direct flame is necessary, and it may be in actual contact with the
substances to be heated, provided these are kept in constant and rapid
motion.
The use of a revolving cylinder brings in complications with any burner
which is supplied with gas at ordinary pressures without any artificial
air supply, as the currents of air caused by the motion of the cylinder
interfere with the satisfactory working of any burner; and the air
supply must be either protected from draughts and irregular air
currents, or the air must be applied artificially from some independent
source. One exceedingly good way of making any burner work,
independently of the currents caused by a revolving cylinder, is to
apply the flame inside the cylinder at the center, making the substances
to be heated to fall in a continuous stream through the flame. This
system is not applicable to fine powders or sticky substances, as it
necessitates the perforation of the cylinder, to allow of the escape of
products of combustion.
For this class of work, a very concentrated heat is not desirable, as a
rule, and a slit or a perforated burner is preferable. Of this class of
burner I have here a sample, which is not only new in its constructive
details, but has great and special advantages for many purposes. As
you see, it resembles a number of ordinary furnace bars, with this
difference, that each bar is a burner; in fact, it is an ordinary
furnace grate, which supplies its own fuel. With the usual day pressure
of gas=1 inch of water, this burner will, at its maximum power, consume
about 100 cubic feet of gas per hour per square foot of burner surface,
and as it can readily be made almost any form or size, its adaptability
for a great number of uses is evident. I have made it in many sizes and
shapes, to give flames from 1/2 inch wide by 5 feet long to large square
or oblong blocks. By applying a blast of air at the ordinary gas jets,
and supplying the gas by a separate pipe, or series of pipes, below
the open end of the burner, this can be converted into a furnace of
extraordinary power. It is quite possible to burn as much as 2,000 cubic
feet of gas per hour per square foot of burner surface, producing a heat
sufficient to fuse any ordinary crucible. You see its power when I place
a bundle of iron wire in the flame; it is, in fact, a concentration of
hundreds or thousands of powerful blowpipe flames in one mass. It has
also this advantage, that with a blast of air it will burn and work
equally well any side up, and the flames can therefore be directed
straight on their work without loss. It is, in one form or another,
almost a universal burner, as it can be readily adapted to almost any
purpose, from tempering a row of needles to making steam for a 200 horse
power steam engine. It is easy to make, easy to manage, practically
indestructible, and for commercial purposes has, I think, a general
adaptability which will bring it, in one form or another, into almost
universal use. I may say that when we are in a special fix, this has in
every case landed us out of the difficulty.
For heating large plates of metal equally, for drying paper impressions
for stereotypers, hot pressing hosiery, crumpet baking, working up
plastic masses which can only be worked hot, and work of this class, a
number of separate flames equally diffused under the whole surface of
the plate are necessary to equalize the heat, unless the plate is very
thick, and these are better if produced by a mixture of gas and air; but
in heating wide plates one difficulty must always be remembered, the
burnt gases from the center flames can only escape by passing over the
outer flames, and therefore a space must be left between the top of the
flame and the plate, or the outer flames will be smothered and make a
most offensive smell.
In hosiery presses, printers' arming presses, and many others, the top
plate also requires to be heated. The best way to do this is to use a
number of blowpipe flames directed downward. In many cases the supply
of air under pressure is a practical difficulty and objection. This is
overcome, to a certain extent, by the use of a thick upper plate with a
number of horizontal holes, into which a Bunsen flame is directed. In
every case I have seen, without one single exception, the holes are
either too small, or the burner is placed too close, and the consequence
is that the gas, instead of burning inside the holes, as it should,
passes through partially unburnt, and is consumed at the opposite end,
where it is absolutely useless, the flame not being in contact with or
under the surface to be heated, and therefore doing no work. In hosiery
presses this is a great objection, as the holes are so long that an
equal heat is simply impossible, and the only remedy is to use a
blowpipe flame, which forces sufficient air in with the gas to insure
combustion where the heat is necessary. The same remark applies to crape
and embossing rollers.
For the production of heat in confined spaces and difficult position,
the use of an artificial blast of air is becoming an acknowledged
necessity, and the small Roots blowers now made for such purposes, and
driven by power, are coming rapidly into use.
Sometimes a plate is required to be heated to a high temperature in one
confined spot, and, as an example of this, I may take the bluing of the
hands of watches. For this purpose I have made several arrangements,
and perhaps the best is a thin copper plate, bent down at one side to a
right angle. In this angle, underneath, is directed a very fine blowpipe
flame on one spot, and the hands are passed singly over this spot until
the color comes, when they are instantly pushed over the edge. I have
here the arrangement which is generally used for this purpose. For the
bluing of clock hands, a larger and more equally heated surface is
required, and this can be obtained by a small powerful burner without
a blast of air, using a rather thicker plate to equalize the heat. The
same arrangement may be used with advantage for tempering small cutters
for ornamental turning, penknife-blades, etc., and in these cases the
cooler part of the plate is of great value, as it enables the thicker
parts to be slowly and equally heated up; the application of a
mechanical arrangement to pass the articles to be heated in a regular
succession is a matter easily managed.
[Illustration: FIG. 3. BLUEING WATCH HANDS & TEMPERING SMALL TOOLS]
Among other things which have several times come under my notice may be
mentioned cremation furnaces, but I have not yet met, with, or been
able to devise, any burner for ordinary coal gas which has worked
satisfactorily. This fuel is apparently unfitted for the work, and
the best arrangement I know is a number of pipes delivering ordinary
"producer" gas from the Wilson or Dowson generators, in exactly the
same way as is at present used for firing horizontal steam boilers. For
heating book finishers' tools, a ring-flame is the simplest, the tools
being supported a little distance above the flame; the usual plan of
heating a plate, and placing the ends of the tools on this, necessitates
at least double the gas consumption as compared with an open flame.
For type-founding machines, bullet moulding, stereotype metal melting,
solder making, lead melting, etc., one burner, or rather one flame,
should be used of a suitable power for the work, and this should be as
perfect and of as high a temperature as possible to insure economy. It
is now a simple matter, owing to recent researches in the theory of
heating burners, to obtain flames of any power without practical limit,
which, without any artificial air supply, will do all which is necessary
in this class of work, and the required arrangements are exceedingly
simple. With these trades may be classed, also, the concentration and
distillation of acids and liquids boiling at a high temperature, and we
may also include baths for tinning small articles, and the tinning by
fusion of sheet copper, the same burners being applicable, and perfectly
suited to all these requirements, unless the tinning baths are long and
narrow, in which case the furnace-bar burners again come to the front as
the best; as, if we are to use gas economically, the flame must be the
same shape as the vessel to be treated.
We may now consider the heating of blanks for stamping, hardening the
points of spindles, finishing the ends of umbrella tips, and work where
a small article, or a small part of any article, has to be heated to a
high temperature with speed and certainty. For these a long and narrow
flame is necessary, and I may mention that in cases where a high speed
of delivery is required, and a small part only has to be heated, such
as, for instance, in the hardening of the points of spindles for cotton
machinery, I have made burners giving a flame of exceedingly high
temperature only 1/4 inch wide and five feet long. This flame is produced
by the assistance of a blast of air, and is of sufficiently high
temperature to fuse the spindle in a few minutes.
The points only project over the flame, and the spindles are carried
mechanically at such a speed that at the end of the five feet traverse
they are red hot, and drop into water. More than one hundred are in the
flame at once, lying side by side.
For heating blanks for stamping, the furnace bar-burner is perfectly
suited, and in this work the chute supplying the blanks to the machine
should be made of two fireclay sides, with an opening for the flame
between the chute and flame being placed at a sharp angle, to prevent
risk of the blanks sticking or overriding each other. A blowpipe may
also be used with good effect, as shown in the above engraving, and in
many cases it is preferable and much easier to manage.
In some cases the direct contact of the flame would spoil the articles
to be heated, and instead of the arrangement mentioned, a tube of iron,
fireclay, or other suitable material is heated, and the articles are
passed through it. This system of continuous feed, through a tube, has
been applied to the firing of small articles of pottery, and might
possibly be well adapted, among other things, to the production of
gas-burners.
[Illustration: FIG. 4.]
Where the contact of air with the heated articles is injurious, many
plans have been tried to keep the ends closed as much as possible, but I
believe no more perfect and simple seal against the admission of air can
be devised than to turn a jet of pure gas, unmixed with air, into each
end of the tube. This is an absolute seal against the entry of oxygen in
an uncombined state; free oxygen cannot exist at a very high temperature
in the presence of coal gas.
For many trades there is a demand for hardened and tempered steel wire,
either round or flattened, and the production of this has led to many
attempts to obtain a satisfactory continuous process. The common method
now, which is worked as a "secret" process by most firms, is to pass
the wire through a tube to heat it, as already described, and to run it
direct from the tube through a hole in the side of a box filled with
oil, the whole being packed with asbestos, to prevent leakage; from this
it is passed through another similar hole on the opposite side, either
over a plate heated to the right temperature, or over a narrow open
flame of sufficient length and power to give the correct heat for
tempering.
Where absolute precision is necessary, the gas supply must be adapted by
an automatic regulator on the main, to prevent the slightest variation
of heat. Once adjusted, the production of flat and round spring wire by
the mile is an exceedingly simple matter. It is quite possible to obtain
absolute precision in temperature by a proper adjustment of the gas
pressure, and as this is, for tempering steel articles and some other
purposes, a matter of great importance, it is worth some consideration.
No pressure regulator alone will give an absolutely steady supply; but
if we put on first a regulator, adjusted to the minimum pressure of
supply, say one inch of water, and then fix another on the same pipe,
adjusted to a slightly lower pressure, say 9/10 of an inch, the first
regulator does the rough adjustment, and the second one will then give
an absolutely steady supply, provided always that the regulators are
both capable of passing more gas than is likely to be ever required. No
regulator can be relied on for absolute precision, if worked up to its
maximum possible capacity.
[Illustration: Fig. 5. ARRANGEMENT FOR HEATING BLANKS FOR STAMPING OR
HARDENING.]
Among other applications of a long narrow flame of high power, may be
mentioned the brazing of long lengths of tube, in fact the application
of flames of this form, with and without a blast of air, for different
temperatures, are almost endless.
The thousands of uses to which blowpipes are adapted are so well known,
that they need no mention, except the curiously ignored fact that the
power of any blowpipe depends on the air pressure. A compact flame of
high temperature cannot be obtained except with a heavy air pressure,
and the ignorance of this fact has caused an immense number of
unexplained failures. Many people think that one blower is as good as
another, and expect that a fan giving a pressure equal to, say, the
height of a two inch column of water should do the same work as a blower
giving a pressure ten to twenty times as great. The construction and
power of blowpipes, with the laws ruling the proportions and power, will
be found in an article on "Blowpipe Construction," published in _Design
and Work_, March, 1881, and as the matter is there fully treated, no
further reference to the subject is necessary.
In the more recent forms of gas-engine, the charge is exploded by a
wrought iron tube, heated to redness by the external application of a
gas flame. This, although considered satisfactory by the makers, appears
to me to be an exceedingly crude way of getting over the difficulty; and
I offer it as a suggestion, that a very small platinum tube shall be
used instead of iron. This, if made with a porous or spongy internal
coating, would fire the charge with certainty, at a lower temperature
than iron, and it could be made so thin and small in diameter, without
risk of deterioration or loss of strength, that an exceedingly small
flame could be used to heat it up. As it would be fully heated in a very
few seconds, the delay in starting would be obviated.
[Illustration: Fig. 6.]
There are many purposes for which a red heat is needed for slow
continuous processes on a small scale, such as case-hardening small
steel goods, annealing, heating light steel articles for hardening, and
a great variety of other similar processes. This, until recently, has
required the use either of a rather complicated furnace, or a blast of
air under pressure, to increase the rapidity of combustion. Since the
conclusion of my experiments on the theoretical construction of burners,
I have found that the high-power burners, previously described, are
capable of heating a crucible equal in size to their own diameter
to bright redness without the assistance of a chimney, provided the
crucible is protected from draughts by a fireclay cylinder.
This is an important point, as it renders the production of a continuous
bright red heat a matter of the greatest ease, even in crucibles of a
comparatively large size. Where the heat is steady, and certain not to
rise above a definite point, it can safely be used for such purposes as
hardening penknife blades and other articles which are very irregular
in thickness, the thin edges not being liable to be burnt or damaged by
overheating.
For the highest temperatures air under pressure is a necessity, as we
require a large quantity of gas burnt in as small a space as possible
with the maximum speed, and given this air supply, we are very little
hampered by conditions, as an explosive mixture may be blown through a
gauze into a fireclay chamber, closed, except so far as is necessary to
allow the escape or burnt gases. The speed of combustion is limited only
by the speed of supply of air and gas, and by increasing these there is
no practical limit to the heat which can be obtained. When we have to
do with the reduction of samples of refractory ores, testing the
comparative fusibility of different samples of firebricks, or alloys,
etc., the use of an explosive mixture blown into and burning in a
close chamber is invaluable, and the ease and certainty with which
any temperature may be obtained has led to great discoveries, and the
revolutionizing of many commercial processes. Recent experiments have
proved that, by a modification in the form of the well-known injector
furnace, an enormous increase of temperature may be obtained. I have,
in actual work, obtained the fusing point of cast iron in two minutes,
starting all cold, and have fused every furnace casing I have yet been
able to produce. If infusible casings can be made, I think I am not
overstating facts in saying that any temperature required can and will
eventually be obtained with the greatest ease. What the limit is I have
as yet not been able to discover.
There is one more application of gas, as a fuel, which, discovered and
published by myself some two years ago, has yet to become generally
known, and in some special processes may prove exceedingly valuable.
This is the addition of a very small quantity or coal gas, or light
petroleum vapors, to the air supplied by a blower or chimney pull,
to furnaces burning coke or charcoal. The instant and great rise in
temperature of the furnace, and the greater stability of the solid fuel
used, are extraordinary. This is, in fact, a practical application of
the well-known "flameless combustion," the only signs that the gas
is being burnt being a great rise in temperature and a decreased
consumption of the solid fuel; in fact, if the gas is in correct
proportion, the solid fuel remains unburnt, or nearly so, in spite of
the high temperature. In cases where a sudden rise in temperature is
required in a furnace, or where the power is deficient, this method
of supplementing and increasing the heat will be found of very great
service, and processes liable to be checked by making up a fire with
fresh fuel can be carried on without check, even after the solid fuel
has almost entirely disappeared.
That a solid fuel is quite unnecessary, I will prove in a very simple
manner, by burning a mixture of coal gas and air without a flame, in a
bundle of iron wire. The heat is sufficient to fuse the wrought iron
with ease, and the glare inside the bundle of wire is painful to the
eyes. The same result could be obtained by a pile of red-hot lumps of
firebrick, and the same heat obtained also without a trace of flame.
It is not possible to enter fully into such a wide and important subject
in a single lecture, and the suggestions now given are simply hints for
the guidance for those who need or desire to experiment. No doubt we
shall have, after a time, some text-books and other literature on this
subject, which is one of great importance to many industries; and it is
necessary for experimental work and applications to new industries, that
the experimenter shall not only be able to purchase special burners, but
that he shall have fundamental laws laid down which will enable him to
construct them for himself, so as to have his experiments under his own
control. The difficulty in the way of literature on the subject is that
those few who have worked in the matter are busy men, with little time
which is not already fully employed.
Pioneers on new ground have a great liability to generalize and jump at
conclusions, and the necessary exact work and detail must, to a great
extent, be left to those who follow on tracks already roughly marked
out.
Of the special trades which have come under my observation, I have only
had time to mention a very few. It appears to me that there are very few
manufacturing processes of any kind which could not be simplified by the
use of gas as a fuel, from the production of electric light apparatus
to the manufacture of explosives, cotton stockings, beer, catgut, glue,
umbrellas, ink, fish-hook, medals, stained glass windows, brushes, and
other trades equally various, which come daily under my own notice.
* * * * *
A man was received into the Laborisiere Hospital, Paris, the other day,
with a yard of rope hanging from his mouth. Traction upon the cord
revealed a section of clothes line measuring eight feet. He had been
surprised in an attempt at suicide and had tried to conceal his design
by swallowing the cord. He lived, of course--they generally do.
* * * * *
INSTANTANEOUS PHOTOGRAPHY.
A certain number of the readers of this journal are occupied with
photography, and all assuredly are interested in this marvelous art,
whose progress is so remarkable. So it has seemed to us that it would
be of interest to treat of a question that is the order of the day. We
desire to speak of those photographic apparatus called instantaneous
shutters.
Numerous apparatus of this kind have been proposed to the public, and
several even have been described in this journal, but we have to state
that, despite the success in certain cases, none of them has proved
remarkable for its qualities and superiority. This is due, we believe,
to the fact that inventors, while showing arrangements that were often
ingenious, have not always taken into account the end that the shutter
is to subserve, and the qualities that it must possess in order to
attain such end.
In face of the progress made by extra rapid dry processes, the question
of shutters has become the most important, since cabinet-making, optics,
and photographic chemistry give us apparatus, objectives, and products
which, although they will doubtless be improved upon, satisfy for the
present all our needs.
What is understood by instantaneousness? To our knowledge, no definition
thereof has as yet been given. For our part, we propose to style
"instantaneous" any photograph that is taken in a fraction of a second
that our senses will not permit us to estimate. The shutter is the
apparatus which allows the light to enter the photographic chamber
during this very short time.
In order to examine the different rules that govern the question of
shutters, we shall take as an example the type styled the "Guillotine."
This apparatus, as every one knows, is a stiff plate containing an
aperture and passing over the line of the rays of light. Some place
it in front and others behind, while others again place it within the
objective. Let us examine and discuss what occurs in the three cases.
Suppose a rectilinear objective of the kind most usually employed in
instantaneous photography, and an object, A B, that we wish to reproduce
(Fig. 1), the objective being provided with any sort of diaphragm. The
point, A, sends a bundle of rays, a"b", to the first lens. Here they are
slightly refracted, and then go on parallel lines to the second lens,
where they are again refracted and form at A' an image of A. It is this
image that we see upon the ground glass, and which makes an impression
upon the sensitive film. The point, B, behaves in the same way and
gives an image at B', but, as will be at once seen, the image will be
reversed. In our figure, A corresponds to the sky and B to the earth.
If, then, the shutter passes in front of the objective, it will first
allow of the passage of the rays which come from the sky, then, on
continuing its travel, it will unveil the landscape, and lastly the
ground. As it is submitted to the law of the fall of bodies and has a
uniformly increasing velocity, it follows that the time of exposure will
uniformly decrease between A' and B', and that the sky will pose longer
than the foreground. Such a result is contrary to all photographic
rules, which require that objects shall pose so much the longer the
less they are lighted. This position of the "guillotine" shutter is
absolutely false, and must be altogether discarded. If the shutter be
placed behind the objective, it will follow, as a consequence of the
same demonstration, that the time of exposure will go diminishing from
B' to A', and that the foreground will be exposed longer than the sky.
The solution is logical, then, and will permit of obtaining excellent
negatives.
[Illustration: FIG. 1]
Let us now examine how the image, A'B', is formed. The point, A, appears
first, and becomes lighter and lighter up to the moment at which all the
rays that emanate from the point, A, are unveiled. The point, B', is not
yet visible. As the shutter continues its travel the point, B', appears
in its turn and becomes illuminated like the point, A'. At this moment
the objective is completely uncovered; the image, A'B', is perfect, and
possesses its maximum intensity. Then the point, A', gradually becomes
obscured and disappears; and the same is the case with all parts of
A'B'. The image is developed progressively from A' to B', and makes its
impression upon the sensitive plate successively--a fact which, as
may be conceived, may have its importance. If, for example, we are
photographing a ship that is being tossed about by the sea (and we
borrow this example from our colleague, Mr. Davanne), the image of the
top of the mast will not be formed at the same instant as that of the
base, and if the motion of the mast has sufficient extent it may take on
a curved form, due to the fact that it has effected a movement between
the moments during which its apex and base were being photographed.
Upon placing the guillotine shutter in the optical center of the
objective, what will occur? The shutter will permit the passage of an
equal fraction of the rays derived from A and B, that is to say, the
image will be complete from the first instant of the exposure. The
points, A' and B', will be illuminated precisely at the same moment. As
the shutter continues its travel, a fresh quantity of rays coming from A
and B will be admitted, and the image will be illuminated more and more
up to the moment at which all the rays can pass. It will then possess
its maximum intensity. Then a portion of the rays from A and B being
intercepted, the image will become darker and darker until complete
extinction. The image here, then, is not produced successively as in the
former case, but is entire from the beginning. In this case the image of
our mast cannot be misshapen, since it has been accurately photographed
at the same moment.
The true place for the guillotine shutter, then, from a theoretical
standpoint, is in the interior of the objective. Are there any other
advantages to be gained by so placing it? Yes; it is easy to understand
that for the same time of exposure, and consequently for the same
result, the aperture may be so much the smaller in proportion as the
optical center is approached.
The luminous rays, in fact, form in the objective a double truncated
cone whose upper base is equal to the diaphragm, and the lower one to
the diameter of the lenses. If the aperture be equal to any diameter
whatever of one of the cones, the result will be the same; but, for
the same period of exposure, it will evidently prove advantageous to
approach the diaphragm. The ratio of the apertures that give the same
results at the optical center or behind the objective is as that of the
diaphragm employed to that of the back lens. If the diaphragm is
one centimeter and the lenses four centimeters, an aperture of one
centimeter in one case and of four in the other will give the same
result.
We shall see further along that it is advantageous to employ apertures
equal to several times the diameter of the diaphragm or lens. Now, from
what we have just said, an aperture, equal for example to four times the
diaphragm, will be only 4 centimeters, while the corresponding aperture
behind the lens must be 16. The dimensions of the first will be
practical, and those of the second will give too cumbersome and too
fragile an apparatus. But why must the aperture be larger than the
diaphragm employed? This is what we are going to demonstrate. Let us
make the aperture equal to the diameter of the objective, and see
what occurs at the different periods of the exposure. For the sake of
clearness, we shall suppose the velocity uniform.
It is evident, _a priori_, that a perfect apparatus will be the one that
will allow the light to act during the entire exposure with a maximum of
intensity. Is it thus, when the aperture is equal to the diameter of the
objective? Evidently not. Let us consult Fig. 2. We here see the shutter
progressively uncovering the objective. The light will increase from A
to C up to the moment when the objective is entirely uncovered, and will
then immediately decrease up to B. The objective has operated with a
maximum of light for only a short time. We are far from the ideal result
in which the maximum of light, CD, should exist during the entire
exposure, and form the upper plane precisely equal to AB.
[Illustration: Fig. 2.]
If we cannot obtain such a result in practice, we must nevertheless
aproximate to it. We shall do so by increasing the shutter. Up to C' the
apparatus will operate as before, but from C' to D' the aperture will be
complete, and from D' to B' will decrease as has been said.
Let us give A'B' the same value as AB, that is to say, let us increase
the velocity in the second case in order that the time of exposure shall
be the same; we shall at once see that in the first case the object will
be completely uncovered for only a very short time, while in the second
the exposure will be perfect for a very appreciable period.
The time of exposure which is absolutely active, we propose to call
effective time of exposure in contradistinction to the total time of the
same. The more we increase the value of C'D', that is to say, that of
the effective time, the more the ratio, C'D'/A'B', will approximate to
unity, and the nearer we shall reach perfection. The correlative of such
elongation of the aperture is an increase in velocity which will always
bring the total exposure to the same figure, whatever be the aperture
employed.
If the aperture be equal to two diameters, the effective time will be
equal to half the time of the total exposure; and if it is equal to
three diameters, the exposure will be good during 2/3 of the total time.
This amounts to saying that the effective time of exposure is equal to n
times the diameter--1, the velocity being supposed always uniform. If
we place the shutter within the objective, it is the diameter of the
diaphragm that it will be necessary to say. The effective time will be
equal then to n diaphragm--1.
From what precedes it results that in no case should the aperture be
inferior to the diaphragm, since the former would otherwise absolutely
suppress the effective time in giving a lower plane corresponding to
an insufficient quantity of light. Moreover, an aperature of this kind
would prove injurious to the quality of the image by successively
uncovering rays which do not form their image identically at the same
point. We are now, then, in presence of results that are absolutely
positive, and they are as follows:
1. The guillotine shutter should be placed in the interior of the
objective and as near as possible to optical center, that is to say,
behind the diaphragm, since the latter is precisely in the optical
center.
2. The aperture should be as wide as possible.
3. The velocity should be as great as possible.
In practice, an aperture from 4 to 5 times the diameter of diaphragm
employed will be more than sufficient, since we shall have, according to
circumstances, 3/4 or 4/5 of the effective time. Moreover, whatever be the
time of exposure, this ratio once established will be invariable, and
the apparatus will always operate identically.
A shutter combining these qualities will not yet be perfect. It is
necessary, according to the time and the light, that the time of
exposure shall be capable of being varied. In a word, it is necessary
that the apparatus shall be _graduated_ and permit of taking views more
or less quickly. The different velocities might be given to the
shutter by means of weights, rubber, or springs. The latter seem to be
preferable, since they permit in the first place of operating out of
the vertical; moreover, they are less fragile, and, through different
tensions, they permit of these graduations that we consider as
indispensable. For the current needs of practice 1/100 of a second is a
limit that seems to us sufficient as a maximum of rapidity. In order to
know the time of exposure obtained we employ the following method, which
permits of graduating an apparatus rapidly and with extreme precision:
A band of smoked paper is fixed upon the shutter, then a tuning-fork
provided with a small stylet resting against the paper is made to
vibrate. Better yet, a chronograph which vibrates synchronously with a
tuning-fork, whose motion is kept up by electricity, is put in the same
place. Fig. 3 shows the arrangement to be employed. We then let the
shutter fall, when the little stylet will inscribe a certain number of
vibrations. Knowing the number of vibrations of the tuning-fork, and
counting the number of those inscribed upon the paper, it is very simple
to deduce therefrom the amount of the time of exposure. The results of
one of these experiments we have reproduced in Fig. 4. The tuning-fork
gave 100 double vibrations per second. Six vibrations are included
between the opening and closing of the apparatus. Each vibration
estimated at 1/100 of a second. The exposure was 6/100 of a second in
round numbers. This is the amount of the total time of exposure. As
for that of the effective time, that is just as easily ascertained. It
suffices to know the number of vibrations comprised between the moment
at which one point of the objective has been completely uncovered and
that at which it has begun to be covered again. The time is equal to
2/100 in round numbers.
In the experiment in question, with an aperture equal to twice the
diameter of the diaphragm, we have, then, 1/3 of the half-open exposure;
and the amount of the effective time is 1/3. The difference that we
have in practice is due to the fact that the velocity is uniformly
accelerated. In order to increase the amount of the effective time, it
will be only necessary to increase the aperture of the shutter and apply
again the method that we have just pointed out.
[Illustration: FIG. 3.]
So much for the material part of the apparatus. It will be necessary
in addition to acquire sufficient individual experience to be able to
estimate the intensity of the light, and consequently to judge of the
diaphragm to be employed and the velocity to be obtained. It must not
be forgotten that such or such an object having a relatively slow speed
will not be sufficiently sharp on the negative if it is too near
the apparatus, while such or such another, much more rapid, might
nevertheless be caught if sufficient distance intervened. Here it is
that will appear the skill of the amateur, who will find it possible to
obtain the said object as large as possible and with a maximum degree of
sharpness.
We have seen what diverse qualities should be possessed by a good
guillotine shutter, and it is evident that the same should be found
in all apparatus of the kind. In our opinion the guillotine is a well
defined type that possesses one capital advantage, and that is that it
permits of the use of aperatures as wide as may be desired for the
same time of exposure. It is a question, as we have seen, of velocity.
Consequently, however short the exposure be, it will always be possible
to operate with a full amount of light during the greater part of the
exposure. It is necessary to dwell upon this point, since in another
kind of apparatus that possesses a closing and opening shutter the same
result cannot be reached. In the Boca apparatus, for instance, we remark
that at a given moment the time of exposure is reduced to nothing, as
the closing shutter covers the objective before the latter has been
unmasked by the opening one. In all exposures, in fact, the times of
opening and closing have a constant value. It follows that the shorter
the exposure is, the greater becomes such value, and to such a point
that, at a given moment, the apparatus no longer make an exposure.
[Illustration: FIG. 4.]
In the guillotine, on the contrary, the same space always intervenes
between the time of opening and closing, since it is fixed in an
unvarying manner by the diameter at the aperature. Then, the greater the
velocity, the more the time of opening and closing diminishes. If
the ratio of the effective to the total time of exposure is 3/4, for
example, it will be invariable, whatever be the velocity.
In concluding, we will remark that, without employing springs, we
may increase the aperture of the shutter without varying the time of
exposure. To effect this it is only necessary to raise the point of the
shutter's drop. In fact, as may be seen in Fig. 4, all the vibrations
of the stylet corresponding to 1/100 of a second always continue to
elongate, and it will consequently be possible for the same time of
exposure to considerably increase the aperture and, as a consequence,
the effective time, by causing the guillotine to drop from a greater
elevation. From this study, which has principally concerned the
guillotine shutter, can we draw the deduction that this type of
apparatus will become a definite one? We think not. In fact, along with
its decided advantages the guillotine has a few defects that cannot be
passed over in silence. The aperture, in measure as it is increased,
renders the apparatus delicate and subject to become bent. If, in order
to obviate this trouble, we employ plates of steels, we increase its
weight considerably, and the chamber becomes subject to vibration at the
moment the shutter drops. If rubber or springs are used for increasing
the velocity, it is still worse. Moreover, it is quite difficult to
obtain a graduation, and to our knowledge, and probably for this reason,
it has not yet been applied.
The reader will please excuse us for this perhaps somewhat dry
theoretical _expose_, but we have thought it well to give it in the
hope that it might well show the qualities that should be required of a
photographic shutter and particularly of the guillotine. Moreover, at
the point to which photography has arrived it is no longer permitted to
do things by halves.
After the memorable discoveries of Nicephore, Niepce, Daguerre, and
Talbot, photography remained for some time stationary, limited to the
production of portraits and landscapes. But for a few years past it has
taken a new impetus, and new processes have come to the surface. In the
graphic arts and in the sciences it has taken considerable place. Being
the daughter of chemistry and physics, it is not astonishing that we
require of it the precision of both. It is, moreover, through a profound
study of the reactions that gave it birth and through a knowledge of the
laws of optics that it has come into current use in laboratories. In
fact, it alone is capable of giving with an undoubted character of
truthfulness a durable vestige of certain fleeting phenomena.--
_A. Londe, in La Nature_.
* * * * *
FALCONETTI'S CONTINUOUSLY PRIMED SIPHON.
To carry a watercourse over a canal, river, road, or railway, several
methods may be employed, as, for example, by aqueducts like those of
Arcueil and Buc near Versailles, and by upright and inverted siphons.
Of these three means, the first is the most imposing, but is also very
costly; and, besides, the declivities as well as the arrangement of the
ground are not always adapted thereto. The inverted siphon is subject
to obstruction and choking up in its most inaccessible parts, while
the upright siphon is easy of inspection, taking apart, etc. But, _per
contra_, the latter loses its priming very easily by reason of the
formation of air spaces.
[Illustration: FALCONETTI'S SIPHON.]
Mr. Falconetti, an inspector of bridges and roadways, has found a means
of rendering the latter occurrence impossible by an arrangement which
is both simple and practical, and which is illustrated herewith. In the
figure, a and b are the two vertical legs of the siphon, both of which
enter the liquid. These open into the receptacles, c and d, in which the
cocks, e and f, cut off or set up a communication with the pipes, a
and b. These latter are connected by a branch, g, which may be put in
communication with a reservoir, h, that is divided into two superposed
compartments by a partition, i. Such communication may be established
or cut off by a valve, j, maneuvered by a key, k, which traverses
an aperture in the partition, i. Another aperture, m, in this same
partition serves to put the two parts of the reservoir, h, in
communication, and, for this purpose, is provided with a cock, n, which
is easily maneuvered from the exterior.
The object of this arrangement of cocks and reservoir is to prevent the
siphon from losing its priming through the possible presence in the
transverse portion of a certain quantity of air or gas that might be
given off by the water and accumulate in this place.
The compartment, A, of the reservoir, h, is designed for receiving the
gases that collect in the top of the siphon, while the upper compartment
contains water for making a hydraulic joint, and consequently preventing
any re-entrance of air through the apertures in the partition, i.
To prime the siphon, we shut the cocks, e and f, open the valves, j and
m, and pour in water until the whole affair (siphon and reservoir) is
full; then we close the cock, m, and open the three others. The siphon
thus becomes primed, and begins to operate as soon as any water reaches
one or the other of the lower receptacles. As the cock, j, is constantly
turned on during the operation of the siphon, the air that has been able
to accumulate in the lower compartment, A, of the reservoir, h, would
finally unprime the siphon by intercepting communication between its two
legs. In order to prevent such a thing from occurring, it suffices to
expel the air, from time to time, that accumulates in the chamber,
A, this being done, without stopping the operation of the siphon, as
follows:
After closing the cock, j, water is poured into the reservoir, and,
running down to the lower compartment, drives out the air through the
cock, m. This operation once effected, it only remains to turn off the
cock, m, again, and open j in order to establish the normal operation.
As the chamber, A, is provided externally with a water gauge, N, it may
be seen at a glance when it is necessary to maneuver the cocks in order
to expel the air.
This system of siphon is evidently applicable to all sorts of liquids.
It may likewise undergo a few modifications in its construction; for
example, the valve, which in our engraving is placed over the siphon,
may be located at any distance from the apparatus, although it should,
in all cases, be in constant communication with it by means of a tube,
and be placed a little higher than the siphon. It may then be put under
cover and be kept constantly in sight, thus greatly facilitating its
surveillance.
As may be seen, the essential peculiarity of this improvement consists
in the very ingenious arrangement that permits of immersing the cocks in
the liquid to make them perfectly tight, it being necessary that they
should be hermetically closed in order to prevent the entrance of air
to the siphon. Everything leads to the belief, then, that if upright
siphons have never been able to operate regularly, it has been because
no means have been known of expelling the air from the interior without
letting air from the exterior enter at the same time. The arrangement
devised by Mr. Falconetti gets over the difficulty in a very elegant
manner. It seems as if it would be called upon to render great services
in the industries, and it well merits the attention of engineers
of roads and bridges, and of contractors on public works.--_Revue
Industrielle_.
* * * * *
THE WEIBEL-PICCARD SYSTEM OF EVAPORATING LIQUIDS.
In the industries, there are often considerable quantities of liquid to
be evaporated in order to concentrate it. Such evaporation is very often
performed by burning fuel in sufficient quantity to furnish the liquid
the heat necessary to convert it into steam. This process is attended
with a consumption of fuel such as to form a very important factor in
the cost of the product to be obtained. In order to vaporize, at the
pressure of the atmosphere, 1 kilogramme of water at 0 deg., 637 heat units
are required, and of these, 100 are employed in raising the water from
0 deg. to 100 deg. and 537 in converting the water at 100 deg. into steam at 100 deg..
This second quantity is called the _latent heat_ of the steam at 100 deg..
The sum of the two quantities is called the _total heat_ of the steam at
100 deg.. The total heat of the steam remains nearly constant, whatever be
the temperature at which the vaporization occurred.
[Illustration: THE WEIBEL-PICCARD EVAPORATION APPARATUS.]
In order to utilize the steam as a means of heating, it is necessary to
condense it, that is to say, to cause it to pass from the gaseous to a
liquid state. This conversion disengages as much heat as the passage
from the liquid to the gaseous state had absorbed.
It results from this that if we could condense the steam that is given
off by a liquid that we are vaporizing, in contact with another liquid
that it is also a question of vaporizing, we should utilize all the heat
contained in the steam that was being given off from the first.
This object can be practically attained by two means, viz., by (1)
putting the disengaged steam in contact with the sides of a vessel that
contains a liquid colder than the one that produced it; (2) by raising
the temperature and pressure of the disengaged steam in order to
condense it in contact with the sides of the vessel which contains the
very liquid that has produced it.
The first of these means is realized in the apparatus called multiple
acting, that are at present so generally employed in sugar works. The
second means, which permits of a greater saving in fuel being made than
the other does, is realized by compressing the disengaged steam. This
compression, which raises the temperature and pressure of the steam,
permits of condensing the latter in contact with the vessel wherein it
has been produced. By such condensation we continuously restore to the
liquid which is being vaporized the heat of the steam which it gives
off.
This solution of the question, which has been partially seen at
different epochs, has but recently made its way into the industries. It
is being operated at present with complete success at the salt works of
France and Switzerland, at those of Austria and Prussia, in the sugar
of milk factories of France and Switzerland, and, finally, in 1882, the
first application of it in the sugar industry was made at Pohrlitz, in
Moravia.
The saving of fuel that has been made in these different applications
has always been great.
We shall now, for the sake of explaining the system, give a brief
description of the apparatus as used at the Pohrlitz sugar works
mentioned above. These works treat 255 tons of beets per 24 hours, and
obtain 4,000 hectoliters of juice, which is reduced to about 1,000
hectoliters of sirup. Up to the present, the concentration has been
effected in a double acting apparatus partly supplied by exhaust steam
from the motive engines and partly by steam coming directly from the
generators.
In order to diminish the consumption of direct steam, these sugar works
put in a Weibel-Piccard apparatus designed to concentrate only a third
of their juice, or about 1,350 hectoliters per day.
This apparatus (see engraving) consists of a steam compressor, 0.835 m.
in diameter, actuated directly by a driving cylinder of 0.5 m. diameter
and 0.8 m. stroke, and of three evaporating boilers of the ordinary
vertical tube type, the first of which has a surface of 150 square
meters, the second 60, and the third 80.
The steam, at the ordinary pressure of the generators, say 5
atmospheres, is taken from the connected generators of the works, and is
led to the driving cylinder, where it expands and furnishes the power
necessary to run the compressor. It then escapes at a pressure of l.4
atmospheres and enters the intertubular space of the first evaporator.
The compressor sucks up the steam from the juice of the first evaporator
(which is boiling at the pressure of the atmosphere, without vacuum or
effective pressure), compresses it to 1.4 atmospheres, and forces it
likewise into the intertubular space. The ebullition of the first
evaporator, then, is kept up not only by the exhaust from the motive
cylinder, but also by the steam from the juice itself, which has been
rendered fit to serve as a heating steam by the pressure that it has
undergone in the compressing cylinder.
In this first application of the new system to sugar making, it became
a question of ascertaining whether the advantage resulting from
compression was of great importance, and, in the second place, whether
the apparatus could be run with certainty and ease. In truth, the
applications of the system for some years past in other industries
permitted a favorable result to be hoped for, and the result turned out
as was expected.
With this apparatus it has been found that the work furnished by one
kilogramme of steam passing through the motive cylinder, from a
pressure of 5 atmospheres to one of 1.4, is sufficient to compress 2.5
kilogrammes of steam taken from the juice, led into the compressor
at one atmosphere and escaping therefrom at 1.4. In other words, one
kilogramme of motive steam is sufficient to convert into heating steam
for the first evaporator 2.5 kilogrammes of steam taken from the juice
in this same evaporator. Besides, this same kilogramme of motive steam
produces three effects, one in this same evaporator, and the other
two in the two succeeding ones. The effect obtained, then, from one
kilogramme of motive steam is, in round numbers, 5.5 kilogrammes of
steam removed from the juice.
It must not be forgotten that the motive steam was at the very moderate
pressure of 4 effective atmospheres. Had the use of steam at high
pressure (7 atmospheres for example) been possible, it is easy to
conclude from the above results that more than 6 kilogrammes of water
would have been vaporized with one kilogramme of steam.
The results here cited were ascertained by accurately measuring the
quantities of water of condensation from each evaporator, they soon
received, moreover, the most important of confirmations by the decrease
in the general consumption of fuel by the generators which occurred
after the new apparatus was set in operation.
The mean consumption of coal per 24 hours for the twenty days preceding
the 18th of November was 86,060 kilogrammes. After this date the regular
consumption was as follows:
Nov. 19.................31,800 kilogrammes.
" 20.................33,800 "
" 21.................33,800 "
" 22.................32,000 "
" 23.................31,400 "
" 24.................31,600 "
" 25.................30,500 "
" 26.................30,500 "
" 27.................28,600 "
" 28.................30,300 "
It must be remarked that in the perfectly regular running of the sugar
works, nothing was changed saving the setting of this evaporating
apparatus running. The same quantity of beets was treated per 24 hours,
and the general temperature remained the same. This remarkable result in
the saving of fuel was brought about notwithstanding the new apparatus
treated but a third, at the most, of the total amount of the juice, the
rest continuing to be concentrated by the double action process.
As for the running of the apparatus, that was perfectly regular, and the
deviations in temperature in each evaporater were scarcely two or three
degrees. The following are the mean temperatures:
First evaporator: heating steam 110 deg. C.; juice steam 100 deg. C. Second
evaporator: juice steam 83 deg. C. Third evaporator: juice steam 62 deg. C. As
regards facility of operating the apparatus, the experiment has proved
so conclusive that the plant will be considerably enlarged in view of
the coming crop, in order that a larger quantity of juice may be treated
by the new process. The effect of this will be to still further increase
the saving in coal that has already been effected by the present
apparatus. The engraving which accompanies this article represents the
Weibel-Piccard apparatus as it is now working in the Pohrlitz sugar
works. What we have said of it above we think will suffice to make it
understood without further explanation.--_Le Genie Civil_.
* * * * *
COMPARISON OF STRENGTH OF LARGE AND SMALL ANIMALS.
W. N. LOCKINGTON.
M. Delebeuf, in a paper read before the Academie Royale de Belgique, and
published in the _Revue Scientique_, reviews the attempts of various
naturalists to make comparisons between the strength of large animals
and that of small ones, especially insects, and shows that ignorance or
forgetfulness of physical laws vitiates all their conclusions.
After a plea for the idea without which the fact is barren, M. Delbeuf
repeats certain statements with which readers of modern zoological
science are tolerably familiar, such as the following: A flea can jump
two hundred times its length; therefore a horse, were its strength
proportioned to its weight, could leap the Rocky Mountains, and a whale
could spring two hundred leagues in height. An Amazon ant walks about
eight feet per minute, but if the progress of a human Amazon were
proportioned to her larger size, she could stride over eight leagues in
an hour; and if proportioned to her greater weight, she would make the
circuit of the globe in about twelve minutes. This seems greatly to the
advantage of the insect. What weak creatures vertebrates must be, is the
impression conveyed.
But the work increases as the weight. In springing, walking, swimming,
or any other activity, the force employed has first to overcome the
weight of the body. A man can easily bound a height of two feet, and
he weighs as much as a hundred thousand grasshoppers, while a hundred
thousand grasshoppers could leap no higher than one--say a foot. This
shows that the vertebrate has the advantage. A man represents the volume
of fifteen millions of ants, yet can easily move more than three hundred
feet a minute, a comparison which gives him forty times more power, bulk
for bulk, than the ant possesses. Yet were all the conditions compared,
something like equality would probably be the result. Much of the force
of a moving man is lost from the inequalities of the way. His body,
supported on two points only when at rest, oscillates like a pendulum
from one to the other as he moves. The ant crawls close to the ground,
and has only a small part of the body unsupported at once. This
economizes force at each step, but on the other hand multiplies the
number of steps so greatly, since the smallest irregularity of the
surface is a hill to a crawling creature, that the total loss of force
is perhaps greater, since it has to slightly raise its body a thousand
times or so to clear a space spanned by a man's one step.
By what peculiarity of our minds do we seem to expect the speed of an
animal to be in proportion to its size? We do not expect a caravan to
move faster than a single horseman, nor an eight hundred pound shot to
move twelve thousand eight hundred times farther than an ounce ball.
Devout writers speak of a wise provision of Nature. "If," say they, "the
speed of a mouse were as much less than that of a horse as its body is
smaller, it would take two steps per second, and be caught at once."
Would not Nature have done better for the mouse had she suppressed the
cat? Is it not a fact that small animals often owe their escape to their
want of swiftness, which enables them to change their direction readily?
A man can easily overtake a mouse in a straight run, but the ready
change of direction baffles him.
M. Plateau has experimented on the strength of insects, and the facts
are unassailable. He has harnessed carabi, necrophori, June-beetles
(Melolontha), and other insects in such a way that, with a delicate
balance, he can measure their powers of draught. He announces the result
that the smallest insects are the strongest proportioned to their size,
but that all are enormously strong when compared bulk, for bulk, with
vertebrates. A horse can scarcely lift two-thirds of its own weight,
while one small species of June-beetle can lift sixty-six times its
weight; forty thousand such June-beetles could lift as much as a
draught-horse. Were our strength in proportion to this, we could play
with weights equal to ten times that of a horse.
This seems, again, great kindness in Nature to the smaller animal. But
all these calculations leave out the elementary mechanical law: "What
is gained in power is lost in time." The elevation of a ton to a given
height represents an expenditure of an equal amount of force, whether
the labor is performed by flea, man, or horse. Time supplies lack of
strength. We can move as much as a horse by taking more time, and can
choose two methods--either to divide the load or use a lever or a
pulley. If a horse moves half its own weight three feet in a second,
while a June-beetle needs a hundred seconds to convey fifty times
its weight an equal distance, the two animals perform equal work
proportioned to their weights. True, the cockchafer can hold fourteen
times its weight in equilibrium (one small June-beetle sixty-six times),
while a horse cannot balance nearly his own weight. But this does not
measure the amount of oscillatory motion induced by the respective
pulls. For this, both should operate against a spring.
A small beetle can escape from under a piece of cardboard a hundred
times its weight. Pushing its head under the edge and using it as a
lever, it straightens itself on its legs and moves the board just a
little, but enough to escape. Of course, we know a horse would be
powerless to escape from a load a hundred times its own weight. His head
cannot be made into a lever. Give him a lever that will make the time he
takes equal to that taken by the insect, and he will throw off the load
at a touch. The fact is that in small creatures the lack of muscular
energy is replaced by time.
Of two muscles equal in bulk and energy the shortest moves most weight.
If a muscular fiber ten inches in length can move a given weight five
inches, ten fibers one inch long will move ten times that weight a
distance of half an inch. Thus smaller muscles have an absolutely
slower motion, but move a greater proportional weight than larger.
The experimenter before mentioned was surprised to find that two
grasshoppers, one of which was three times the bulk of the other,
leaped an equal height. This was what might be expected of two animals
similarly constructed. The spring was proportioned to the bulk. In
experiments on the insects with powerful wings, such as bees, flies,
dragon-flies, etc., it was found that the weight they could bear without
being forced to descend was in most cases equal to their own. In some
cases it was more, but the inequality of rate of flight, had it been
taken into the reckoning, would have accounted for this.
Take two creatures of different bulk but built upon exactly the same
plan and proportions, say a Brobdingnagian and a Lilliputian, and let
both show their powers in the arena. Suppose the first to weigh a
million times more than the second. If the giant could raise to his
shoulder, some thirty-five feet from the ground, a weight twenty
thousand pounds, the dwarf can raise to his shoulder, not, as might be
thought, a fiftieth of a pound, but two full pounds. The distance raised
would be a hundred times less. In a race the Lilliputian, with a hundred
skips a second, will travel an equal distance with the giant, who would
take but a skip in a second. The leg of the latter weighs a million
times the most, but has only ten thousand times as many muscle fibers,
each a hundred times longer than those of the dwarf, who thus takes one
hundred skips while the giant takes one. The same physical laws apply to
all muscles, so that, when all the factors are considered, muscles of
the same quality have equal power.--_Am. Field._.
* * * * *
OIL IN CALIFORNIA.
J.W. McKinley, writing to the Pittsburg _Dispatch_, gives the following
account of the California oil field at Newhall:
On the edge of the town is located the refinery of the company,
connected by pipe lines with the wells, a few miles distant. Leaving
Newhall, we drove to Pico Canon, the principal producing territory of
the region. As we approached, we saw, away up on the peaks, the tall
derricks in places which looked inaccessible; but no spot is out of
reach of American enterprise and perseverance. In one of the wildest
spots of the canon, about thirty men were making the mountains echo to
the strokes of their hammers upon the iron plates of a new 20,000 barrel
tank. Along the canon are scattered the houses of the employes of the
company, most of whom have recently come from Pennsylvania. Near one of
the houses was a graded and leveled croquet ground, with a little oil
tank on a post, for lighting it at night. Farther up we came to a
cluster of producing wells, with others at a little distance on the
sides of the mountains, or even at the top, hundreds of feet above our
heads.
The first well was put down about eight years ago, but more has been
accomplished in the last two years than in all the time previous. One
well which we visited has produced 130,000 barrels in the last three
years, and is still yielding. There have been no very large wells, the
best being 250 per day, and the average being about 90 barrels, but they
keep up their production, with scarcely any diminution from year to
year. Drilling has been found difficult, as a great portion of the rock
is broken shale lying obliquely. The tools slip to one side very easily,
and a number of "crooked holes" have resulted. One driller lost his
tools altogether in a well, and finished it with new ones. The cost of
putting down a well is from $5,000 to $7,000, depending upon depth, etc.
Most of the wells are from 1,200 to 1,500 feet, but some have yielded at
a much less depth. One well of 270 feet depth produced 40 barrels per
day for about three years, has been deepened, and is now yielding even
more. Another one of 800 feet is said to have produced 200,000 barrels
in the last five or six years. Drilling has been very successful in
striking oil in paying quantities wherever there were indications of its
presence.
The Pacific Oil Company now has 27 wells producing or drilling, and
during the last two years has been rapidly widening the scope of its
operations. It has now from 30 to 40 miles of pipe lines, and is
preparing to lay 20 miles more, to connect its land with ocean shipping
at Ventura. The producers of California have a great advantage in their
proximity to the ocean, which gives them free commerce with the outside
world. Crude oil is now sold at $3 per barrel in Los Angeles, and the
oil companies are making immense profits. There is a very large amount
of oil territory as yet undeveloped, and a rich reward awaits enterprise
in these regions. In the Camulos District, which lies west of the San
Fernando, are even stronger surface indications of oil than there
were in the Pico Canon. We first went up the Brea Canon, in which are
numerous outbursts and springs of oil. Ascending the mountain west of
this canon, we could plainly see the break in the mountains crossing
from the San Fernando through this district to those beyond which
have been developed. A couple of miles farther west, the Hooper Canon
stretches back over two miles into the mountain, and is full of oil.
Great pools of oil fill its water courses, that are dry at present.
Hundreds of barrels of oil must be wasted away and evaporated during a
year. A well put down only 90 feet by horse power, struck light oil in
considerable quantity, and, had it not been for the death of one of the
owners and the consequent suspension of operations, would doubtless have
yielded in large quantities at the depth of a few hundred feet.
The mountainous territory between these two canons will probably in a
few years be the scene of great activity. In the Little Sespe District,
a few miles west of Camulos, a 125 barrel well was struck at 1,500
feet recently. The Santa Paula region, a little farther west, is also
yielding large profits to the parties developing it.
* * * * *
NUTRITIVE VALUE OF CONDIMENTS.
By HELEN D. ABBOTT, Assistant in the Chemical Laboratory of the
Philadelphia Polyclinic, and College for Graduates in Medicine.
The prevailing opinion respecting the substances known as condiments
is, that they possess essentially stimulating qualities, rendering them
peculiarly fitted for inducing, by reflex action, the secretion of the
alimentary juices. Letheby gives, as the functions of condiments,
such as pepper, mustard, spices, pot-herbs, etc., that besides their
stimulating properties they give flavor to food; and by them indifferent
food is made palatable, and its digestion accelerated. He enumerates as
aids to digestion--proper selection of food, according to the taste of
the individual, proper treatment of it as regards cooking, and proper
variation of it, both as to its nature and treatment.
While it is difficult to give an entirely satisfactory definition as to
what constitutes food, the following extracts from standard works
will serve as guides. Hermann[1] says: "The compound must be fit
for absorption into the blood or chyle, either directly, or after
preparation by the processes of digestion, i.e., it must be digestible.
It must replace directly some inorganic or organic constituent of the
body; or it must undergo conversion into such a constituent, while in
the body; or it must serve as an ingredient in the construction of such
a constituent." He further says that water, chlorides, and phosphates
are the most indispensable articles of diet. Watts[2] states that
"whatever is commonly absorbed in a state of health is perhaps the best,
or rather the truest, definition of food."
[Footnote 1: Elements of Human Physiology, by L. Hermann. Translated by
Gamgee.]
[Footnote 2: Dictionary of Chemistry, vol. iv., pages 147-8.]
Chemical analysis shows that the most important and widely applicable
foods contain carbon, hydrogen, oxygen, nitrogen, and mineral matter,
the latter containing phosphates and chlorides. Other things being
equal, it may be considered that the comparative nutrient value of
two articles is in proportion to the amounts of carbon, nitrogen, and
phosphoric acid they contain.
"The food of man also contains certain substances known under the name
of condiments. Since these bodies perform their functions outside the
real body, though within the alimentary canal, they have no
better reason to be considered as food than has hunger, _optimum
condimentum_."[1] Such is the positively expressed opinion of Foster,
the author of the article on nutrition in Watts' Dictionary of
Chemistry. With a view of determining how far the common condiments
deserve this summary dismissal, a number of analyses have been made in
the laboratory of the Philadelphia Polyclinic. My examinations were
especially directed to the mineral matter, phosphoric acid, and
nitrogen. The following table shows the result of the analyses:
Percent. Percent.
of ash. of P_{2}O_{5}.
Fennel........................ 9.00 .103
Marjoram...................... 8.84 .050
Peppermint.................... 8.80 .016
Thyme......................... 8.34 .122
Poppy......................... 7.74 .024
Sage.......................... 7.58 .033
Caraway....................... 7.08 .118
Spearmint..................... 7.06 .017
Coriander..................... 6.10 .097
Cloves........................ 5.84 .563
Allspice...................... 5.54 .017
Mustard....................... 3.90 .134
Black pepper.................. 3.60 .011
Jamaica ginger................ 3.16 .052
Cinnamon...................... 3.02 .009
Mace.......................... 2.44 .230
Nutmeg........................ 2.24 .092
Celery........................ 1.29 .082
White pepper.................. 1.16 .017
Aniseed....................... 1.05 .113
[Footnote 1: Ibid., page 149.]
The articles were examined in the condition in which they were
obtained in the market, without any preliminary drying, selecting, or
preparation. The ash was obtained by burning in a platinum crucible, at
as low a temperature as possible, dissolving in hydrochloric acid the
phosphoric acid separated as ammonium molybdo-phosphate, and determined
in the usual manner.
Qualitative tests made for nitrogen indicated its presence in each one
of the condiments examined.
It is of importance to observe that the majority of these condiments are
fruits, ripe or nearly so. The seed appropriates to itself the nitrogen
and the greatest nutritive properties for the development of the future
plant. All nutritive substances fall into two classes: the one serves
for the repair of the unoxidizable constituents of the body, the other
is destined to replace the oxidizable. Condiments fulfill both of
these requirements, as is shown by a study of their composition; the
phosphoric acid and nitrogen are taken up by the tissues, as from other
substances used in diet. Some articles affect the character of the
excretions; this is often due to essential oils; the presence of these
in the excretions cannot be said to diminish the value of the substances
in supplying the tissues the necessary elements. The same holds true for
condiments; the essential oils conspicuous in them are accorded only
stimulating properties; however, it may be observed that the essential
oils in tea and coffee are accredited with a portion of the dietetic
value of these beverages. It appears that when condiments are used in
food, especially for the sick, they may serve the double purpose of
rendering the food more appetizing and of adding to its nutritive value.
The value of food as a purely therapeutic agent is attracting some
attention at present, and in its study we must not neglect
those substances which combine stimulant and nutritive
qualities.--_Polyclinic_.
* * * * *
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