SCIENTIFIC MISCELLANY.
THE FORCE OF CRYSTALLIZATION.
The old story of a bombshell filled with water and left to burst by freezing, upon the plains of Abraham, near Quebec, may now be superseded as an illustration of the power of frost. The men at a Western dockyard were surprised to find one morning that the paddle-wheel of a steamer in the dry dock had fallen from the shaft, and was broken in two pieces. The hub of the wheel, about fifteen inches long, was slightly hollowed out at the centre to admit of its being slipped on without difficulty over any uneven portion of the shaft-end. This recess was full of water when the boat was placed in the dock, and the keying had been so close that the liquid—about a pailful—was exposed to the frost. As the water congealed under the sharp wintry atmosphere of the night it expanded and burst asunder the five-inch walls of iron, and the broken wheel fell with a crash.
FROZEN NITRO-GLYCERINE.
Two accidents, both fatal, have lately occurred from the use of nitro-glycerine for blasting. In one case some frozen cartridges were recklessly placed in the oven of a stove, while others were held up to the fire. That an explosion should take place under such circumstances is not surprising, and comment is unnecessary. The other explosion partook more clearly of the nature of an accident. A well digger, living near Sing Sing, had buried a can of nitro-glycerine in his garden for future use; and while digging it up, January 18, his pick struck the can, ignition followed, and he was blown to pieces. No doubt the can was frozen, thus proving anew that frozen nitro-glycerine is more dangerous to handle, though not so powerful in its effects, as in the liquid form. This is singular behavior and contrary to theory. In general terms, explosion may be defined as the result which takes place when a portion of the nitro-glycerine is raised to a given temperature. Now, to produce this temperature by the friction resulting from the blow of a pick is manifestly more difficult with frozen than with tepid liquid. In the former case some of the heat produced would be absorbed by the liquefaction of the solid substance, and therefore there would be less available for producing the temperature of explosion. But, plain as this proposition is, there must be some unknown condition, for it has been frequently observed in practical work that nitro-glycerine is never so dangerous to handle as when frozen. This result, however, is directly opposed to the experiments of Beckerhinn, of Vienna, who lately experimented to decide this question. He placed a thin layer of nitro-glycerine on a Bessemer steel anvil, and a weight of about five pounds, having a small hardened steel face, was dropped upon it. The height to which it was necessary to raise this weight in order to produce explosion determined the comparative delicacy of the explosive. With tepid nitro-glycerine explosion took place when the weight dropped about 31 inches (0.78 metres), but with frozen liquid the fall had to be increased to about 85 inches (2.13 metre). Thus the experimental results are opposed to the acknowledged experience of practical work in the hands of common laborers. Mr. Beckerhinn found the density of the solid nitro-glycerine to be 1.735, that of the liquid 1.599, and the average melting heat to be 33.54 heat units. Thus the explosive shrinks about one-twelfth in crystallizing.
ENGLISH GREAT GUNS.
The largest rifled cannon in the world is a 100-ton gun, made for the Italian government by Sir William Armstrong's firm. But the English government is preparing to outdo this, and already has the plans ready for a gun of 164 tons. It hesitates, in fact, between a weapon of this size and one of 200 tons, a mass of metal which its shops are now perfectly able to handle. The meaning of the term—200-ton gun—is simply this: a tube of iron and steel of that weight, fifty feet long, having a calibre of 20 inches, and firing a shot of 3,500 or 4,000 pounds weight, with a charge of 800 pounds of powder! The human capacity for astonishment has grown perforce as the successive steps have been taken from the guns of ten and twenty tons to these weapons, which must remain huge whatever further advances are made. The character of warfare with them is best indicated by the fact that the 200-ton gun must be handled entirely by machinery. The advent of these unmanageable weapons is signalized by the invention of a hydraulic apparatus for working them. The vast shock of the recoil from the bursting of thirty-two kegs of powder—enough to throw down 1,200 tons of rock in mining—is taken up by a cylinder pierced with small holes. These holes are capped with valves, held down with a pressure of fifty tons to the square inch. When the force of the recoil exceeds this the water is forced out of the holes and the recoil thus taken up in work done. The breech of the piece is supported on a hydraulic ram, the elevation of which depresses the muzzle of the gun below the level of the deck, and brings it exactly in line with an iron tube carrying the sponge. This is run up to the base of the powder chamber, a deluge of water rushes from apertures in its head, and the bore is completely cleaned out and every spark of remaining fire extinguished. The rammer then retires, the sponge is taken off, and the powder hoisted by tackle to the muzzle, whence the rammer pushes it home, and then does the same for the shot. The shot and cartridge, weighing together about 1,350 pounds, are stored on little iron carriages, every charge in the magazine having its own carriage. The loading finished, the gun is raised, pointed, the port flies open, and the discharge immediately follows. What the result of the blow from such a projectile would be is not to be imagined. It is acknowledged, however, that in the struggle for mastery the gun has beaten defensive armor. No ship has been built to stand the shock of a 3,500 pound bolt moving at the velocity of 1,300 or 1,500 feet a second.
EAR TRUMPETS FOR PILOTS.
Prof. Henry has turned his attention to the discovery of means for increasing the distinctness of sound signals at sea. It is a very large hearing trumpet, projecting mouth foremost from the top of the pilot-house of a steamboat. But he soon found that a single hearing trumpet would not answer the purpose, for though it greatly augmented the perceptive power of the ear, it destroyed the capacity of that organ for distinguishing the direction of sound. For this purpose two ears are necessary. Prof. Henry then made use of two hearing trumpets, the axes of which are separated about 30 inches. An india-rubber tube proceeding from the axis of each is placed so as to terminate in the ear of the observer—one in each ear. With this instrument the audibility of the sound was very much increased, but as a means of determining the direction of the source of sound, it was apparently of little use. For this purpose the unaided ear is sufficient, provided the head is placed above all obstructions and away from reflections.
HOT WATER IN DRESSING ORES.
We have before alluded to the investigations made to ascertain the reason why clay settles more rapidly in solutions of some salts than in pure water, a fact which appears contrary to reason, since it might be inferred that the greater the specific gravity the more buoyant the fluid. But the fact is abundantly confirmed, and it is likely to find important application some day in the arts. The property which every substance has of sinking through a fluid of less density than its own forms the basis upon which nine-tenths of the gold and copper, and probably six-tenths of the silver produced in this country, is extracted from its ores. It is the foundation of the art of ore dressing, one of the most important parts of metallurgy. Anything which increases the rapidity and thoroughness of the process may have a fortunate application in this art. Mr. Ramsay, of the Glasgow university laboratory, thinks the property in question depends upon the varying absorption of heat by the different solutions. When water containing suspended clay is heated the rapidity of settling is proportional to the heat of the water. This mode of accelerating the movement of fine sediments in water is perhaps more easily applied than the solution of caustic soda or potash, or of common salt. Rittinger, by a mathematical discussion of the principles which control the downward movement of solid particles in an ascending stream of water, showed that the separation of light from heavy minerals is more complete with solutions of density greater than that of water than in water alone. He found a solution of 1.5 sp. gr. extremely favorable. If the addition of heat will increase the effect of such a solution, it may become possible to separate, by means of the continuous jig, minerals so near in specific gravity as barite and galena. This whole subject of ore dressing is one of the most important questions connected with the future of mineral industry in America. In the Mississippi valley everything connected with metallurgy, from the fuels to the finished metal, will one day be closely dependent on it.
OCEAN ECHOES.
Prof. Henry communicated to the National Academy at Philadelphia his latest researches into the subject of sound, and among them an explanation of the echo observed on the water. This echo he had formerly been inclined to attribute to reflection from the crests of the waves. Tyndall holds that it is due to reflection from strata of air at different densities. Prof. Henry's present explanation is that this echo is produced by the reflection of the sound wave from the uniform surface of the water. The effect of the echo is produced by the fact that the original sound wave is interrupted. It has what the learned Professor calls shadows, produced by the intervention of some obstacle in its path. Sound is not propagated in parallel, but in diverging lines, and yet there are some cases where what may be called a "sound shadow" is produced. For instance, let a fog-signal be placed at or near water level on one side of an island that has a conical elevation. Then the signal will be heard distinctly by a vessel on the opposite side of the island at a distance of three miles. But when the vessel sails toward the island (the signal being on the opposite side), the sound will be entirely lost when the distance is reduced to a mile, and in any smaller distance it is not recovered. In this case the station of the vessel at the shorter distance is in the "sound shadow." The termination of that shadow is the point at which the diverging beams of sound, passing over the crest of the island, bend down and reach the surface of the water. The formation of the sound echo may be explained by this extreme divergence of the sound waves, for it is rational to suppose that at a great distance from the source of sound some of the dispersed waves will reach the water surface at such an angle as to be reflected back to the hearer. This was well illustrated by an experiment made to test Tyndall's theory. A steam siren was pointed straight upward to the zenith, but no echo from the zenith was heard, though the presence of a cloud from which a few raindrops fell certified the presence of air strata of different densities. But, strange to say, an echo was heard from every part of the horizon, half of which was land and half water. The only explanation of this fact is that the sound waves projected upward were so dispersed as to reach the earth's surface at a certain distance, and at that point some of them had curled over and assumed a direction that caused their reflection back to the siren.
THE DELICACY OF CHEMISTS' BALANCES.
In making chemical balances for fine work the beam is made in the truss form to prevent the bending which takes place even under such small loads as an ounce or two. Prof. Mendeleef has a balance that will turn with one-thousandth of a grain, when each pan is loaded with 15,000 grains. This extreme sensibility is obtained by the use of micrometer scales and cross threads at the end of the beam, these being observed by means of a telescope. Of course one weighing with this complicated apparatus occupies a long time. In most balances the beam rests on steel knife edges; but a maker who has lately obtained celebrity makes his supports of pure rock crystal. The steel edges can be seen with the naked eye; the quartz edges cannot be seen even with a magnifying glass. One writer on this subject thinks that with these perfect crystal edges, with an inflexible girder beam, a short beam giving quick vibrations, and a sensitiveness that can be increased by screwing up the centre of gravity, there can hardly be a practical limit to the smallness of the weight that will turn the beam. The amount of motion may be very small, but if this can be observed, the limit of possible accuracy is very much extended.
GOVERNMENT CONTROL OF THE DEAD.
What the population of European countries was a hundred years ago it would be hard to tell with accuracy; but the nations have doubled and trebled in strength within the century. Sanitary precautions have increased in importance, and the very noticeable movement in regard to social hygiene which now possesses English society is perhaps due in part to the obvious dangers to which thirty million human beings are subjected when living together on such a small area. The medical officer for Birkenhead has pointed out that it may be necessary for the government authorities to take more complete charge of the dead as a possible source of infection. He says that the intelligence of deaths from infectious diseases now furnished by local registrary would be much more useful than it is as a means for limiting the spread of disease if the medical officer were vested with further powers in respect to the infected dead body. At present neither the medical officer nor any one else has any power to order the immediate removal of an infected body, and those in charge of it might do what they liked with it. He advocated the necessity of power being given to medical officers to order the immediate removal of the infected bodies to a public mortuary and their speedy burial.
MICROSCOPIC LIFE.
Dr. Leidy lately described to the Academy of Sciences in Philadelphia an encounter for life which he witnessed between two microscopic animalcules. The two creatures were respectively 1-625th and 1-200th of an inch in diameter. On the morning of August 27, from some mud adhering to the roots of sphagnum, obtained the day previously in a nearly dried-up marsh at Bristol, Pennsylvania, he obtained a drop of material for examination with the microscope. After a few moments he observed an amoeba verrucosa, nearly motionless, empty of food, with a large central vesicle, and measuring 1/25th of a millimetre in diameter. Within a short distance of it, and moving directly toward it, was another and more active amoeba, regarding the species of which he was not positive. It was perhaps the one described by Dujardin as amoeba limax, by which name it may be called. As first noticed, this amoeba was one-eighth of a millimetre long, with a number of conical pseudopods projecting from the front border, which was one-sixteenth of a millimetre wide. The creature contained a number of spherical food spaces with sienna colored contents, a large diatom filled with endochrome, besides several clear food spaces, a posterior contractile vesicle, and the usual glanular endosarc. The amoeba limax approached and came into contact with the motionless amoeba verrucosa. Moving to the right, it left a long finger-like pseudopod curved around its lower half, and then extended a similar one around the upper half until it met the first pseudo-pod. After a few moments the ends of the two projections actually became continuous, and the verrucosa was enclosed in the embrace of the amoeba limax. The latter assumed a perfectly circular outline, and after a while a uniformly smooth surface. It now moved away with its new capture, and after a short time what had been the head end contracted and became wrinkled and villous in appearance, while from what had been the tail end ten conical pseudopods projected. The amoeba verrucosa assumed an oval form, and the contractile vesicle became indistinct without collapsing. Moving on, the amoeba limax became more slug-like in shape. The amoeba verrucosa now appeared enclosed in a large oval, clear vacuole or space, was constricted so as to be gourd-shaped, and had lost all trace of its vesicle. Subsequently it was doubled upon itself, and at this point the amoeba limax discharged from one side of the tail end the siliceous case of the diatom, which now contained only a shrivelled cord of endochrome. Later the amoeba verrucosa was broken up into fine spherical granular balls, and these gradually became obscured and apparently diffused among the granular contents of the endosarc of the amoeba limax. The observations from the time of the seizure of the amoeba verrucosa to its digestion or disappearance among the granular matter of the entosarc of its captor, occupied seven hours. From naked amoeba the shell-protected rhizopods were no doubt evolved, and it is a curious sight to observe them swallowed, home and all, to be digested out of their house. It was also interesting to observe the cannibal amoeba swallowing one of its own kind and appropriating its structure to its own use, just as we might do the contents of an egg. The amoeba verrucosa he describes as remarkable for its sluggish character, and in appearance reminds one of a little pile of epithelial scales or a fragment of dandruff from the head. It is oval or rounded, transparent, and more or less wrinkled, or marked with delicate, wavy lines.
THE SOURCES OF POTABLE WATER.
In the British Social Science meeting, Mr. Latham, a civil engineer of London, brought up the question of water supplies and endeavored to find rules for the guidance of water engineers in those apparently contradictory facts which the observation of recent years has produced so abundantly. It has been generally considered that water which has received the sewage of large populations must be unfit for domestic use; but careful investigation would show that when such polluting matter has been passed into a river, and exposed to the influence of light, vegetation, etc., it becomes innocuous. This is shown by the good health enjoyed by the inhabitants of London, which place receives its supply chiefly from the Thames and the Lea, both of which rivers receive a considerable amount of sewage pollution. The author instanced Wakefield, Doncaster, and Ely as towns that draw their supplies of water from sources into which sewage matter enters, and yet whose inhabitants are healthy. The cholera epidemic at Newcastle-on-Tyne in 1853 was supposed to have been caused by the use of polluted Tyne water, and yet it was clearly ascertained that disease was much more rife among those persons who used local well water. These facts, which have often been quoted, were not favorably received by the audience, who greeted with laughter Mr. Latham's assertion that water into which sewage matter has entered can be purified by a short exposure to the air. That statement may be too strong; but there is acknowledged truth in the author's main point. He considered it was clearly proved that water derived from underground sources, or from which light and air have been excluded, is impure, and consequently unfit for domestic use. Universal testimony showed that decaying matter easily found its way into underground sources of supply. Well water may become seriously contaminated by the slow steeping of noxious matters, and be less wholesome than the water of a running stream that receives much larger quantities of impurity.
THEORY OF THE RADIOMETER.
Prof. Crookes has at length announced a theory in explanation of the movements exhibited by the remarkable "light mill" of his invention. He says: "The evidence afforded by the experiments is to my mind so strong as almost to amount to conviction, that the repulsion resulting from radiation is due to the action of thermometric heat between the surface of the moving body and the case of the instrument, through the intervention of the residual gas. This explanation of its action is in accordance with recent speculations as to the ultimate constitution of matter, and the dynamical theory of gases." The most refined means for exhausting the air from the glass bulb which contains the suspended vanes of the radiometer leave, and if they were to be carried to absolute mechanical perfection, would still leave a certain amount of gas in it. But Dr. Crookes has carried this attenuation so far that the number of gas molecules present can no longer be considered as practically infinite. Nor is the mean length of their paths between their collisions any longer very small compared to the size of the bulb. The latest use to which the radiometer has been put was to test the viscosity of gases at decreasing pressures. The glass bulb was furnished with a stopper lubricated with burnt rubber. This was fixed and carried a fine thread of glass which is almost perfectly elastic. To the end of this thread hung a thin oblong plate of pith to which a mirror was attached. The glass stopper being fixed, and the bulb capable of rotation through a small angle, it is evident that when the bulb is rotated the pith ball will remain at rest except as it yields to the friction of the air moved by the bulb. It does move, swinging a certain distance and then back, like a pendulum. The amount of this movement is carefully observed by a telescope, and recorded for five successive beats. As the pith and glass fibre form a torsion pendulum, it is evident that these beats will gradually die down in consequence of the resistance of the air. By exhausting the air to various degrees of rarity, it was proved that Prof. Clerk Maxwell's theory, that the viscosity of a gas is independent of its density, is correct. The logarithmic decrement of the first five oscillations (that is, the decrease, oscillation by oscillation, of the logarithm of the arc through which the pith vanes swing), was found to be nearly the same when the air was almost exhausted as when it was at its natural pressure, proving that its viscosity remained nearly equal for all pressures. Only in the exceptionally perfect vacuum referred to above did this logarithmic decrement sink to about one-twentieth of what it had commenced with. Repulsion of the vane by the action of light commences when this decrement is one-fourth of what it was before the exhaustion of air began. As the rarity of the air within the bulb increases the force of this repulsion begins to diminish, like the logarithmic decrement, and when the latter has sunk to one-twentieth the former has fallen off one-half. All these and other facts previously obtained prove that the action of light is not direct, but indirect; and Dr. Crookes has, after repeatedly refusing to consider hasty judgments, in consequence come to the conclusion stated above, that the rotation of the light mill is the result of heat. This decision accords with the opinion of other observers. The radiometer has already entered the field of industrial science, and is used to measure the duration of exposure of photographic plates. De Fonvielle has made with it a new determination of the sun's thermometric power. He made a spectroscope with a graduated screen, which permitted the amount of light that entered the apparatus to be graduated at will. In the path of the beam he placed a radiometer, and by comparing its action in the graduated light ray, and in the light of a standard oil lamp, burning 42 grammes (11.3 ounces Troy) per hour, he found that at 4 o'clock, on June 4, 1876, the radiating force of the sun was equal to 14 lamps placed 25 centimetres (10 inches) from the radiometer.
TEMPERED GLASS IN THE HOUSEHOLD.
The "tempered glass," which has made the name of M. de la Bastié, its discoverer, so well known, does not prove to be always manageable. It was to have the strength of metal, and not shiver with changes of temperature. But an English lady has found that it sometimes has precisely the contrary characteristics. She purchased twelve globes for gaslights, and they were made in the manufactory of M. de la Bastié himself. But one night, after the gas had been extinguished for exactly an hour, one of the globes burst with a report, and fell in pieces on the floor, leaving the bottom ring still on the burner. These pieces, which were of course found to be perfectly cold, were some two or three inches long and an inch or so wide. They continued for an hour or more splitting up and subdividing themselves into smaller and still smaller fragments, each split being accompanied by a slight report, until at length there was not a fragment larger than a hazel nut, and the greater part of the glass was in pieces of about the size of a pea, and of a crystalline form. In the morning it was found that the rim had fallen from the burner to the floor in atoms. In all these phenomena the behavior was that of unannealed glass, of which so many curious performances have been related.
THE NEW YORK AQUARIUM.
A marine and fresh-water aquarium has been opened in New York, and both from its intrinsic merits and as the first attempt to institute in this country a valuable mode of scientific amusement and instruction, it deserves mention. It does not equal in size or arrangements any of the celebrated places of the kind abroad. Still it contains tanks of considerable size, and in them some very interesting denizens. The shark, sturgeon, skate, sea-turtle, and other fishes are represented by large individuals, and their habits can be watched at leisure. A small white whale was also at one time one of the attractions. Fish breeding is carried on in the establishment, which receives constant additions to its occupants by expeditions which are said to be especially planned for this purpose. In any case New York is an excellent point for an aquarium, and probably receives every year enough rare living fish at its great markets to maintain such an institution. The commencement now made is a worthy one, and it can easily become an important source of pleasure and usefulness. The system employed is that of constant circulation, the water being pumped from a reservoir to the several tanks. Pumps and pipes are made of hard rubber. A library, a naturalists' laboratory, equipped with tables, microscopes, etc., are either established or projected in the building.
THE CRUELTY OF HUNTING.
The outcry against the practice of making surgical experiments upon living dogs, rabbits, and other animals has roused some vivisectionists to return to the subject of hunting. This is one of the principal themes of the philosophic philanthropist, whose opposition to the practice seems to be an outgrowth of the better acquaintance which man has made, through science, with the lower animals. He accomplishes his task very effectively by calculating the number of animals which are wounded but not recovered by English sportsmen every year. The official returns show that in 1873-'4 there were 132,036 holders of gun licenses, and 65,846 holders of licenses to kill game in the British dominions. In 1874-'5 the numbers were 144,278 and 68,079, showing that the disposition and ability to hunt are on the increase. As a basis for computation, the partridge season of 21 weeks is taken, and two days' hunting are allowed for each week; while three birds are supposed to be wounded and "lost" daily by each sportsman. This gives 126 birds wounded and left to suffer unknown torments by each one of the 68,079 holders of game licenses. The total is no less than 8,296,496 "lost" birds in 1873-'4, and 8,577,954 in 1874-'5. Then the holders of gun licenses have the right to shoot birds which are destructive to crops, etc., and two lost birds each week in the year is calculated to be the average. This makes no less than 13,731,744 wounded birds in 1873-'4, and 15,004,912 in 1874-'5. The total is in round numbers twenty million birds injured each year! These estimates are made by "Nature," and they correctly represent the ground on which the modern opposition to the hunt as a cruel and unnecessary occupation is based. Of course the figures are not exact. The only effort made was to have them within bounds; and considering all the varieties of game pursued in England, and the extraordinary keenness of Englishmen for sport, this estimate is probably correct. Quite lately they have been confirmed by a noted hunter on the western plains, who says that in his case a day's sport was usually marked by the "loss" of two or three animals. As he is an uncommon shot, his experience cannot be more unfortunate than the average. Such calculations show us how enormous are the results when the whole human race engages in one action. At present, English society offers the contradictory spectacle of a large and increasing body of hunters who oppose vivisection on the ground of cruelty, and a small and increasing body of vivisectionists who oppose hunting also on the ground of cruelty.
THE GORILLA IN CONFINEMENT.
Great interest attaches to the career of the young gorilla now in the Berlin aquarium. Dr. Hermes described some of his peculiarities at a late meeting of the German Association of Naturalists and Physicians. He nods and claps his hands to visitors; wakes up like a man, and stretches himself. His keeper must always be beside him and eat with him. He eats what his keeper eats; they share dinner and supper. The keeper must remain by him till he goes to sleep, his sleep lasting eight hours. His easy life has increased his weight in a few months from thirty-one to thirty-seven pounds. For some weeks he had inflammation of the lungs, when his old friend Dr. Falkenstein was fetched, who treated him with quinine and Ems water, which made him better. When Dr. Hermes left the gorilla on the previous Sunday the latter showed the doctor his tongue, clapped his hands, and squeezed the hand of the doctor as an indication, the latter believed, of his recovery. Apparently he means to support, by every means in his power, the effort at a hot-house development of the ape to the man. A large glass house has been built for him in connection with the palm house.
INSTRUCTION SHOPS IN BOSTON.
The Boston Institute of Technology is somewhat noted for its boldness in making educational experiments; its efforts so far having been directed toward the introduction of practical trade instruction into an advanced school. Some years ago it endeavored to establish a model room for dressing ores and another for smelting them; but the success of this trial seems to be more than doubtful. Both of these pursuits are too extensive to be represented by one shop or by sample work. Nothing daunted by this failure, President Runkle has lately introduced a "filing shop" as the first step toward practical instruction in engineering work. This shop has about thirty work tables, each provided with a vise and tool drawers. Filing is one of the first things the young apprentice has to learn; and those who think that anybody can file who has hands may be surprised to learn that the filing of a hexagon bolt head is one of the tests for a Whitworth prize scholarship. The difficulty of making a flat surface is in that task combined with the necessity of having the faces of equal size and placed at equal angles to each other. The plan in the Boston institute is to have the student spend ten weeks in filing, and then the same length of time in each the forging shop and the turning shop. The two latter are not yet ready. These three steps form part of a two years' course in mechanical engineering, the tuition fee to which is $125 yearly. The main objection to such schools is that engineers and practical men persist in refusing to accept such instruction as a substitute for actual work. The Boston institute is making praiseworthy efforts, but it seems to be adopting a system which has never been in favor just at a time when the smelting works and machine shops of the country appear willing to unite with the scientific schools in supplying students with real experience of work as a requirement for a diploma.
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A new mode of compressing arteries is by the use of a hard pad having a prominent projection, which is pressed against the artery or vein by a strong elastic ring of rubber passed over the limb.
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The Harvard summer schools were so far successful that the last catalogue reports forty students in geology, twenty-five in chemistry, twenty-five in phenogamic botany, and six in cryptogamic botany.
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A case in which the heart was severely wounded without causing immediate death lately occurred in England. The wound was made by a knife which passed between the third and fourth ribs, through the wall of the heart into the cavity of the left ventricle. The man lived sixty-four hours.
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M. Peligot warns housekeepers against the advice so often given, to use borax for the preserving of meat. He finds that borax and the borates affect plants very seriously, and doubts whether it can be innocuous to animals. French beans watered once with a solution of borax quickly withered and died.
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A young American, Dr. James by name, was killed with his partner (a Swede) at Yule Island in September last, by the natives of New Guinea. They were hunting birds of paradise at the time. Dr. James left some valuable collections which have been described before the Linnæan Society of London.
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In extending the underground railway of London, the excavations disclosed Roman and other remains of considerable interest. Among the former there were found fragments of urns, specimens of pottery, and bronze coins. The most remarkable discovery was that of a thick stratum of bullock's horns, commencing about twenty feet below the surface, and extending to an unascertained distance beneath. Although the deposit was doubtless made many centuries ago, the horns had suffered so little by decay that they found a ready sale in the market. This road has carried in thirteen years 408,500,000 passengers. In 1863, the first year, the number was 9,500,000, which increased to 48,500,000 last year.
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Foreign papers say that Mr. Floyd, the President of the board of trustees for the Lick donation, has come to an arrangement with M. Leverrier, the celebrated French astronomer, for the better execution of the instruments to be made for the Lick Observatory. The masses of glass required are to be made in Paris, at Feil's glass works, and the object-glasses very likely by an English optician.
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Two distinguished men were officially superannuated last year: Profs. Milne-Edwards and Delafosse of the Paris Museum. The son of the former takes his place, and Descloiseaux succeeds to the chair of mineralogy. Professors Dove of Berlin and Wöhler of Göttingen have had their jubiläum or fiftieth anniversary of their doctorates. All these facts illustrate the conservative influence of student life.
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The Western mines of gold and silver have lately yielded some new and interesting minerals. Roscoelite is a vanadium mica from a gold mine at Granite creek, California. The vanadic acid varies from 20 to 23 per cent. Psittacinite is a vanadate of lead and copper, which occurs associated with gold, lead, and copper minerals at several mines in Silver Star district, Montana. It is considered to be a favorable indication, for when that is found the vein is said to become rich in gold. Coloradoite is a telluride of mercury, also a new mineral and quite rare.
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Dr. Piggott proposes to replace the spider's web of telescopes by a star illuminated transit eye-piece. A sheet of glass, on which a thin film of silver is deposited, is placed in the focus of the eye lens; transparent lines are drawn on the film, instead of wires, and as the star passes across the lines it is seen to flash out brightly. The film of silver is made sufficiently thin to permit of the star being seen when it is between the lines, but it appears that the lines themselves are only visible, except in the case of very large stars, when the star disc is in transit across a line.
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Singular results of strains existing in the granite rocks through which the St. Gothard tunnel is passing are recorded. When the shots are fired at the end of the gallery they are sometimes succeeded at unequal intervals by other explosions at points where there is no drill hole and no powder. Workmen have been injured by these spontaneous explosions, which are to be explained only on the theory that there are strains in the rock; and when this tension is increased by the shock of a heavy explosion, the rock flies in pieces with noise. Similar effects have been noticed in other granites.
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It is said that aniline colors are now used to color wines, and that enough of them is taken into the Bordeaux district of France to color one-third of its whole product. Husson gives the following method for detecting it: Take a small quantity of the wine and add a little ammonia, when the mixture turns a dirty green. Steep a thread of white woollen yarn in the liquor and allow a drop of vinegar to flow along it. If the color of the wine is natural, as the drop advances the original whiteness of the wool is restored; but if the wine has been sophisticated with magenta, the wool will take a rose color. This test is simple, easily tried, and effective.
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An inquiry into the results of systematic gymnastic exercises in a French military school shows that the strength is increased on the average 15 to 17 per cent., and is also equalized on both sides of the body. The capacity of the chest is increased at least 16 per cent. and the weight 6 to 7 per cent. Coincident with this increase is a decrease in the bulk of the body, showing that fat is changed to muscle. The improvement is confined to the first three months of the course unless the exercise is then moderated. If continued at too high a rate, weakness succeeds the increase of strength. It would be a good plan to place a dynamometer in every gymnasium as a measure of the changes which take place in the gymnast.
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MOON MADNESS.
The popular belief that the moon's rays will cause madness in any person who sleeps exposed to them has long been felt to be absurd, and yet it has appeared to have its source in undoubted facts. Some deleterious influence is experienced by those who rashly court slumber in full moonshine, and probably there is no superstition to which the well-to-do pay more attention. Windows are often carefully covered to keep the moonbeams from entering sleeping rooms. A gentleman living in India furnishes "Nature" with an explanation of this phenomenon which is at least plausible. He says: "It has often been observed that when the moon is full, or near its full time, there are rarely any clouds about; and if there be clouds before the full moon rises, they are soon dissipated; and therefore a perfectly clear sky, with a bright full moon, is frequently observed. A clear sky admits of rapid radiation of heat from the surface of the earth, and any person exposed to such radiation is sure to be chilled by rapid loss of heat. There is reason to believe that, under the circumstances, paralysis of one side of the face is sometimes likely to occur from chill, as one side of the face is more likely to be exposed to rapid radiation, and consequent loss of its heat. This chill is more likely to occur when the sky is perfectly clear. I have often slept in the open in India on a clear summer night, when there was no moon; and although the first part of the night may have been hot, yet toward two or three o'clock in the morning, the chill has been so great that I have often been awakened by an ache in my forehead, which I as often have counteracted by wrapping a handkerchief round my head, and drawing the blanket over my face. As the chill is likely to be greatest on a very clear night, and the clearest nights are likely to be those on which there is a bright moonshine, it is very possible that neuralgia, paralysis, or other similar injury, caused by sleeping in the open, has been attributed to the moon, when the proximate cause may really have been the chill, and the moon only a remote cause acting by dissipating the clouds and haze (if it do so), and leaving a perfectly clear sky for the play of radiation into space."
THE ARGUMENT AGAINST VACCINATION.
An English physician opposes compulsory vaccination on the ground that it prevents further discovery, and compels medical science to halt at just that point, because it forbids experiment upon methods of prevention that may prove to be better. He says: "It stereotypes a particular stage of scientific knowledge, and bars further progress. If I remind you of the great improvement thought to have been made by the introduction of inoculation by Lady Mary Wortley Montagu at the end of the last century, and ask you to suppose that Parliament might then have passed an act to compel every one to be inoculated, you will, I think, see what is meant. This method was tried for some years with great éclat, but afterward it was found to spread the smallpox so much that an act of Parliament was passed to forbid its use. Vaccination, introduced by Dr. Jenner, has followed, and this was another step in advance. I was the first child in my father's family vaccinated seventy-one years ago, several elder brothers and sisters having been inoculated. Both methods answered in our cases. But for many years I have been satisfied that other diseases besides the modified small-pox (called cow-pox) are now introduced by the old vaccine, and have steadily refused to use it, seeking rather, at increased trouble and expense, new vaccine. And the question which comes forcibly to the front is this: May not some other preservative be discovered which shall be a further improvement? This question cannot be answered so long as vaccination is compelled by law. There are no persons upon whom experiments can be tried." So far as it goes, this is valid ground for criticising vaccination laws. But the proof that small-pox is more disastrous to the human race than the evils that vaccination brings with it is so strong that there is little likelihood society will subject itself to the attacks of the greater enemy in order to avoid the lesser. The evils of the old system of using vaccine taken from human beings for new inoculations are now no longer inevitable. Fresh vaccine direct from the calf, and called "Bovine," can be had everywhere. A large establishment for obtaining it is situated near New York.