Read Ebook: Scientific American Supplement No. 460 October 25 1884 by Various

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Improved Textile Machinery.--The Textile Exhibition at Islington.--5 figures.

Endless Rope Haulage.--2 figures.

Simple Devices for Distilling Water.--4 figures.

Improved Fire Damp Detecter.--With full description and engraving.

Camera Attachment for Paper Photo Negatives.--2 figures.

Instantaneous Photo Shutter.--1 figure.

Sulphurous Acid.--Easy method of preparation for photographic purposes.

The Sunshine Recorder.--1 figure.

On the Evolution of Forms of Art.--From a paper by Prof. JACOBSTHAL.--Plant Forms the archetypes of cashmere patterns.--Ornamental representations of plants of two kinds.--Architectural forms of different ages.--20 figures.

The Voyage of the Vettor Pisani.--Shark fishing In the Gulf of Panama.--Capture of Rhinodon typicus, the largest fish in existence.

Raising Ferns from Spores.--1 figure.

The Life History of Vaucheria.--Growth of alga vaucheria under the microscope.--4 figures.

The Greely Arctic Expedition.--With engraving.

The Nile Expedition.--1 figure.

LINKS IN THE HISTORY OF THE LOCOMOTIVE.

In "Wood on Railroads," second edition, 1832, page 377, we are told that "after those experiments"--the Rainhill trials--"were concluded, the Novelty underwent considerable alterations;" and on page 399, "Mr. Stephenson had also improved the working of the Rocket engine, and by applying the steam more powerfully in the chimney to increase the draught, was enabled to raise a much greater quantity of steam than before." Nothing is said as to where the new experiments took place, nor their precise date. But it seems that the Meteor and the Arrow--Stephenson engines--were tried at the same time; and this is really the only hint Wood gives as to what was done to the Rocket between the 6th of October, 1829, and the 15th of September, 1830.

THE FLOW OF WATER THROUGH TURBINES AND SCREW PROPELLERS.

Literature relating to turbines probably stands unrivaled among all that concerns questions of hydraulic engineering, not so much in its voluminous character as in the extent to which purely theoretical writers have ignored facts, or practical writers have relied upon empirical rules rather than upon any sound theory. In relation to this view, it may suffice to note that theoretical deductions have frequently been based upon a generalization that "streams of water must enter the buckets of a turbine without shock, and leave them without velocity." Both these assumed conditions are misleading, and it is now well known that in every good turbine both are carefully disobeyed. So-called practical writers, as a rule, fail to give much useful information, and their task seems rather in praise of one description of turbine above another. But generally, it is of no consequence whatever how a stream of water may be led through the buckets of any form of turbine, so long as its velocity gradually becomes reduced to the smallest amount that will carry it freely clear of the machine.

In the limits of a short paper it is impossible to do justice to more than one aspect of the considerations relating to turbines, and it is now proposed to bring before the Mechanical Section of the British Association some conclusions drawn from the behavior of jets of water discharged under pressure, more particularly in the hope that, as water power is extremely abundant in Canada, any remarks relating to the subject may not fail to prove interesting.

Between the action of turbines and that of screw propellers exists an exact parallelism, although in one case water imparts motion to the buckets of a turbine, while in the other case blades of a screw give spiral movement to a column of water driven aft from the vessel it propels forward. Turbines have been driven sometimes by impact alone, sometimes by reaction above, though generally by a combination of impact and reaction, and it is by the last named system that the best results are now known to be obtained.

The ordinary paddles of a steamer impel a mass of water horizontally backward by impact alone, but screw propellers use reaction somewhat disguised, and only to a limited extent. The full use and advantages of reaction for screw propellers were not generally known until after the publication of papers by the present writer in the "Proceedings" of the Institution of Naval Architects for 1867 and 1868, and more fully in the "Transactions" of the Society of Engineers for 1868. Since that time, by the author of these investigations then described, by the English Admiralty, and by private firms, further experiments have been carried out, some on a considerable scale, and all corroborative of the results published in 1868. But nothing further has been done in utilizing these discoveries until the recent exigencies of modern naval warfare have led foreign nations to place a high value upon speed. Some makers of torpedo boats have thus been induced to slacken the trammels of an older theory and to apply a somewhat incomplete form of the author's reaction propeller for gaining some portion of the notable performance of these hornets of the deep. Just as in turbines a combination of impact and reaction produces the maximum practical result, so in screw propellers does a corresponding gain accompany the same construction.

IMPROVED TEXTILE MACHINERY.

ENDLESS ROPE HAULAGE.

No. 2 system was peculiar to Wigan. A double line of rails is always used. The rope rests upon the tubs, which are attached to the rope either singly or in sets varying in number from two to twelve. The other engraving shows a mode of connection between the tubs and the rope by a rope loop as shown.

The tubs are placed at a regular distance apart, and the rope works slowly. Motion is given to the rope by large driving pulleys, and friction is obtained by taking the rope several times round the driving pulley.

A RELIABLE WATER FILTER.

Opinions are so firmly fixed at present that water is capable of carrying the germs of disease that, in cases of epidemics, the recommendation is made to drink natural mineral waters, or to boil ordinary water. This is a wise measure, assuredly; but mineral waters are expensive, and, moreover, many persons cannot get used to them. As for boiled water, that is a beverage which has no longer a normal composition; a portion of its salts has become precipitated, and its dissolved gases have been given off. In spite of the aeration that it is afterward made to undergo, it preserves an insipid taste, and I believe that it is not very digestible. I have thought, then, that it would be important, from a hygienic standpoint, to have a filter that should effectually rid water of all the microbes or germs that it contains, while at the same time preserving the salts or gases that it holds in solution. I have reached such a result, and, although it is always delicate to speak of things that one has himself done, I think the question is too important to allow me to hold back my opinion in regard to the apparatus. It is a question of general hygiene before which my own personality must disappear completely.

In Mr. Pasteur's laboratory, we filter the liquids in which microbes have been cultivated, so as to separate them from the medium in which they exist. For this purpose we employ a small unglazed porcelain tube that we have had especially constructed therefor. The liquid traverses the porous sides of this under the influence of atmospheric pressure, since we cause a vacuum around the tube by means of an air-pump. We collect in this way, after several hours, a few cubic inches of a liquid which is absolutely pure, since animals may be inoculated with it without danger to them, while the smallest quantity of the same liquid, when not filtered, infallibly causes death.

This is the process that I have applied to the filtration of water. I have introduced into it merely such modifications as are necessary to render the apparatus entirely practical. My apparatus consists of an unglazed porcelain tube inverted upon a ring of enameled porcelain, forming a part thereof, and provided with an aperture for the outflow of the liquid. This tube is placed within a metallic one, which is directly attached to a cock that is soldered to the service pipe. A nut at the base that can be maneuvered by hand permits, through the intermedium of a rubber washer resting upon the enameled ring, of the tube being hermetically closed.

Under these circumstances, when the cock is turned on, the water fills the space between the two tubes and slowly filters, under the influence of pressure, through the sides of the porous one, and is freed from all solid matter, including the microbes and germs, that it contains. It flows out thoroughly purified, through the lower aperture, into a vessel placed there to receive it.

I have directly ascertained that water thus filtered is deprived of all its germs. For this purpose I have added some of it to very changeable liquids, such as veal broth, blood, and milk, and have found that there was no alteration. Such water, then, is incapable of transmitting the germs of disease.

With an apparatus like the one here figured, and in which the filtering tube is eight inches in length by about one inch in diameter, about four and a half gallons of water per day may be obtained when the pressure is two atmospheres--the mean pressure in Mr. Pasteur's laboratory, where my experiments were made. Naturally, the discharge is greater or less according to the pressure. A discharge of three and a half to four and a half gallons of water seems to me to be sufficient for the needs of an ordinary household. For schools, hospitals, barracks, etc., it is easy to obtain the necessary volume of water by associating the tubes in series. The discharge will be multiplied by the number of tubes.

SIMPLE DEVICES FOR DISTILLING WATER.

The alchemists dreamed and talked of that universal solvent which they so long and vainly endeavored to discover; still, for all this, not only the alchemist of old, but his more immediate successor, the chemist of to-day, has found no solvent so universal as water. No liquid has nearly so wide a range of dissolving powers, and, taking things all round, no liquid exercises so slight an action upon the bodies dissolved--evaporate the water away, and the dissolved substance is obtained in an unchanged condition; at any rate, this is the general rule.

The function of water in nature is essentially that of a solvent or a medium of circulation; it is not, in any sense, a food, yet without it no food can be assimilated by an animal. Without water the solid materials of the globe would be unable to come together so closely as to interchange their elements; and unless the temperatures were sufficiently high to establish an igneous fluidity, such as undoubtedly exists in the sun, there would be no circulation of matter to speak of, and the earth would be, as it were, locked up or dead.

When we look upon water as the nearest approach to a universal solvent that even the astute scientist of to-day has been able to discover, who can wonder that it is never found absolutely pure in nature? For wherever it accumulates it dissolves something from its surroundings. Still, in a rain-drop just formed we have very nearly pure water; but even this contains dissolved air to the extent of about one-fiftieth of its volume, and as the drop falls downward it takes up such impurities as may be floating in the atmosphere; so that if our rain-drop is falling immediately after a long drought, it becomes charged with nitrate or nitrite of ammonia and various organic matters--perhaps also the spores or germs of disease. Thus it will be seen that rain tends to wonderfully clear or wash the atmosphere, and we all know how much a first rain is appreciated as an air purifier, and how it carries down with it valuable food for plants. The rain-water, in percolating through or over the land, flows mainly toward the rivers, and in doing so it becomes more or less charged with mineral matter, lime salts and common salt being the chief of them; while some of that water which has penetrated more deeply into the earth takes up far more solid matter than is ordinarily found in river water. The bulk of this more or less impure water tends toward the ocean, taking with it its load of salt and lime. Constant evaporation, of course, takes place from the surface of the sea, so that the salt and lime accumulate, this latter being, however, ultimately deposited as shells, coral, and chalk, while nearly pure or naturally distilled water once more condenses in the form of clouds. This process, by which a constant supply of purified water is kept up in the natural economy, is imitated on a small scale when water is converted into steam by the action of heat, and this vapor is cooled so as to reproduce liquid water, the operation in question being known as distillation.

For this purpose an apparatus known as a still is required; and although by law one must pay an annual license fee for the right to use a still, it is not usual for the government authorities to enforce the law when a still is merely used for purifying water.

One of the best forms of still for the photographer to employ consists of a tin can or bottle in which the water is boiled, and to this a tin tube is adapted by means of a cork, one end of this tin tube terminating in a coil passing through a tub or other vessel of cold water. A gas burner, as shown, is a convenient source of heat, and in order to insure a complete condensation of the vapor, the water in the cooling tub must be changed now and again.

Sometimes the vapor is condensed by being allowed to play against the inside of a conical cover which is adapted to a saucepan, and is kept cool by the external application of cold water; and in this case the still takes the form represented by the subjoined diagrams; such compact and portable stills being largely employed in Ireland for the private manufacture of whisky.

It is scarcely necessary to say that the condensed water trickles down on the inside of the cone, and flows out at the spout.

An extemporized arrangement of a similar character may be made by passing a tobacco pipe through the side of a tin saucepan as shown below, and inverting the lid of the saucepan; if the lid is now kept cool by frequent changes of water inside it, and the pipe is properly adjusted so as to catch the drippings from the convex side of the lid, a considerable quantity of distilled water may be collected in an hour or so.

The proportion of solid impurities present in water as ordinarily met with is extremely variable: rain water which has been collected toward the end of a storm contains only a minute fraction of a grain per gallon, while river or spring water may contain from less than thirty grains per gallon or so and upward. Ordinary sea water generally contains from three to four per cent. of saline matter, but that of the Dead Sea contains nearly one-fourth of its weight of salts.

The three impurities of water which most interest the photographer are lime or magnesia salts, which give the so-called hardness; chlorides , which throw down silver salts; and organic matter, which may overturn the balance of photographic operations by causing premature reduction of the sensitive silver compounds. To test for them is easy. Hardness is easily recognizable by washing one's hands in the water, the soap being curdled; but in many cases one must rather seek for a hard water than avoid it, as the tendency of gelatine plates to frill is far less in hard water than in soft water. It is, indeed, a common and useful practice to harden the water used for washing by adding half an ounce or an ounce of Epsom salts to each bucket of water. Chlorides--chloride of sodium or common salt being that usually met with--may be detected by adding a drop or two of nitrate of silver to half a wineglassful of the water, a few drops of nitric acid being then added. A slight cloudiness indicates a trace of chlorides, and a decided milkiness shows the presence of a larger quantity. If it is wished to get a somewhat more definite idea of the amount, it is easy to make up a series of standards for comparison, by dissolving known weights of common salt in distilled or rain water, and testing samples of them side by side with the water to be examined.

Organic matters may be detected by adding a little nitrate of silver to the water, filtering off from any precipitate of chloride of silver, and exposing the clear liquid to sunlight; a clean stoppered bottle being the most convenient vessel to use. The extent to which a blackening takes place may be regarded as approximately proportionate to the amount of organic matter present.

IMPROVED FIRE-DAMP DETECTER.

If such is the case, Mr. Garforth seems to have struck the key-note when, in the recent paper read before the Midland Institute of Mining and Civil Engineers, and which we have now before us, he says: "It would seem from the foregoing remarks that in any existing safety-lamp where one qualification is increased another is proportionately reduced; so it is doubtful whether all the necessary requirements of sensitiveness, resistance to strong currents, satisfactory light, self-extinction, perfect combustion, etc., can ever be combined in one lamp."

The nearest approach to Mr. Garforth's invention which we have ever heard of is that of a workman at a colliery in the north of England, who, more than twenty years ago, to avoid the trouble of getting to the highest part of the roof, used a kind of air pump, seven or eight feet long, to extract the gas from the breaks; and some five years ago Mr. Jones, of Ebbw Vale, had a similar idea. It appears that these appliances were so cumbersome, besides requiring too great length or height for most mines, and necessitating the use of both hands, that they did not come into general use. The ideas, however, are totally different, and the causes which have most likely led to the invention of the ball and protected tube were probably never thought of until recently; indeed, Mr. Garforth writes that he has only learned about them since his paper was read before the Midland Institute, and some weeks after his patent was taken out.

No one, says Mr. Garforth, in his paper read before the Midland Institute, will, I presume, deny that the Davy is more sensitive than the tin shield lamp, inasmuch as in the former the surrounding atmosphere or explosive mixture has only one thickness of gauze to pass through, and that on a level with the flame; while the latter has a number of small holes and two or three thicknesses of gauze , which the gas must penetrate before it reaches the flame. Moreover, the tin shield lamp, when inclined to one side, is extinguished ; and as the inlet holes are 6 inches from the top, it does not show a thin stratum of fire-damp near the roof as perceptibly as the Davy, which admits of being put in almost a horizontal position. Although the Davy lamp was, nearly fifty years ago, pronounced unsafe, by reason of its inability to resist an ordinary velocity of eight feet per second, yet it is still kept in use on account of its sensitiveness. Its advocates maintain that a mine can be kept safer by using the Davy, which detects small quantities of gas, and thereby shows the real state of the mine, than by a lamp which, though able to resist a greater velocity, is not so sensitive, and consequently is apt to deceive. Assuming the Davy lamp to be condemned , the Stephenson and some of the more recently invented lamps pronounced unsafe, then if greater shielding is recommended the question is, what means have we for detecting small quantities of fire-damp?

It would seem from the foregoing remarks that in any existing safety-lamp, where one qualification is increased another is proportionately reduced; so it is doubtful whether all the necessary requirements of sensitiveness, resistance to strong currents, satisfactory light, self-extinction, perfect combustion, etc., can ever be combined in one lamp. The object of the present paper is to show that with the assistance of the fire-damp detecter, the tin shield, or any other description of lamp, is made as sensitive as the Davy, while its other advantages of resisting velocity, etc., are not in any way interfered with. As a proof of this I may mention that a deputy of experience recently visited a working place to make his inspection. He reported the stall to be free from gas, but when the manager and steward visited it with the detecter, which they applied to the roof , it drew a sample of the atmosphere which, on being put to the test tube in the tin-shield lamp, at once showed the presence of fire-damp. Out of twenty-eight tests in a mine working a long-wall face the Davy showed gas only eleven times, while the detecter showed it in every case. The detecter, as will be perceived from the one exhibited, and the accompanying sectional drawing, consists simply of an oval-shaped India rubber ball, fitted with a mouthpiece. The diameter is about 2 1/4 inches by 3 inches, its weight is two ounces, and it is so small that it can be carried without any inconvenience in the coat or even in the waistcoat pocket. Its capacity is such that all the air within it may be expelled by the compression of one hand.

The mouthpiece is made to fit a tube in the bottom of the lamp, and when pressed against the India rubber ring on the ball-flange, a perfectly tight joint is made, which prevents the admission of any external air. The tube in the bottom of the lamp is carried within a short distance of the height of the wick-holder. It is covered at the upper end with gauze, besides being fitted with other thicknesses of gauze at certain distances within the tube; and if it be found desirable to further protect the flame against strong currents of air, a small valve may be placed at the inlet, as shown in the drawing. This valve is made of sufficient weight to resist the force of a strong current, and is only lifted from its seat by the pressure of the hand on the mouthpiece. It will be apparent from the small size and elasticity of the detecter that the test can easily be made with one hand, and when the ball is allowed to expand a vacuum is formed within it, and a sample of the atmosphere drawn from the breaks, cavities, or highest parts of the roof, or, of course, any portion of the mine. When the sample is forced through the tube near the flame, gas if present at once reveals itself by the elongation of the flame in the usual way, at the same time giving an additional proof by burning with a blue flame on the top of the test tube. If gas is not present, the distinction is easily seen by the flame keeping the same size, but burning with somewhat greater brightness, owing to the increased quality of oxygen forced upon it.

I venture to claim for this method of detecting fire-damp among other advantages: 1. The detecter, on account of its size, can be placed in a break in the roof where an ordinary lamp--even a small Davy--could not be put, and a purer sample of the suspected atmosphere is obtained than would be the case even a few inches below the level of the roof, 2. The obtaining and testing of a sample in the manner above described takes away the possibility of an explosion, which might be the result if a lamp with a defective gauze were placed in an explosive atmosphere. No one knows how many explosions have not been caused by the fire-trier himself. This will now be avoided. 3. The lamp can be kept in a pure atmosphere while the sample is obtained by the detecter, and at a greater height than the flame in a safety-lamp could be properly distinguished. The test can afterward be made in a safe place, at some distance from the explosive atmosphere; and, owing to the vacuum formed, the ball has been carried a mile or more without the gas escaping. 4. The detecter supplies a better knowledge of the condition of the working places, especially in breaks and cavities in the roof; which latter, with the help of a nozzle and staff, may be reached to a height of ten feet or more, by the detecter being pressed against the roof and sides, or by the use of a special form of detecter. 5. Being able at will to force the contents of the detecter on to the flame, the effects of an explosion inside the lamp need not be feared. 6. The use of the detecter will permit the further protection of the present tin shield lamp, by an extra thickness of gauze, if such addition is found advantageous in resisting an increased velocity. 7. In the Mueseler, Stephenson, and other lamps, where the flame is surrounded by glass, there is no means of using the wire for shot firing. The detecter tube, although protected by two thicknesses of gauze, admits of this being done by the use of a special form of valve turned by the mouthpiece of the detecter. The system of firing shots or using open lamps in the same pit where safety lamps are used is exceedingly objectionable; still, under certain conditions shots may be fired without danger. Whether safety lamps or candles are used, it is thought the use of the detecter will afford such a ready means of testing that more examinations will be made before firing a shot, thereby insuring greater safety. 8. In testing for gas with a safety lamp there is a fear of the light being extinguished, when the lamp is suddenly placed in a quantity of gas, or in endeavoring to get a very small light; this is especially the case with some kinds of lamps. With the detecter this is avoided, as a large flame can be used, which is considered by some a preferable means of testing for small quantities; and the test can be made without risk. Where gas is present in large quantities, the blue flame at the end of the test tube will be found a further proof. This latter result is produced by the slightest compression of the ball. As regards the use of the detecter with open lights, several of the foregoing advantages or modifications of them will apply. Instead of having to use the safety lamp as at present, it is thought that the working place will be more frequently examined, for a sample of the suspected atmosphere can be carried to a safe place and forced on to the naked light, when, if gas be present, it simply burns at the end of the mouthpiece like an ordinary gas jet. There are other advantages, such as examining the return airways without exposing the lamp, etc., which will be apparent, and become of more or less importance according to the conditions under which the tests are made.

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