Chapter VIII: MISCELLANEOUS.--Mont St. Michel, Normandy.--With engraving (4)

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.

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.

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A man was received into the Laborisière 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.

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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.

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.

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, ¾ 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.

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.

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_.

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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.

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_.

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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°, 637 heat units are required, and of these, 100 are employed in raising the water from 0° to 100° and 537 in converting the water at 100° into steam at 100°. This second quantity is called the _latent heat_ of the steam at 100°. The sum of the two quantities is called the _total heat_ of the steam at 100°. The total heat of the steam remains nearly constant, whatever be the temperature at which the vaporization occurred.

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° C.; juice steam 100° C. Second evaporator: juice steam 83° C. Third evaporator: juice steam 62° 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_.

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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 Cañon, 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 cañon, 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 cañon 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.