Popular Science Monthly/Volume 3/September 1873/Miscellany
Fish-Culture In New Zealand.—Last January a large quantity of salmon-eggs from English waters was shipped to New Zealand. They would reach their destination in 112 days, but it was a question whether they would bear so protracted a journey, though carefully packed and surrounded by ice. To determine this question, four boxes of ova, packed after the same manner as those sent to New Zealand, were deposited at the office of a London ice company. After the lapse of 112 days, these boxes were opened, and the temperature was then found to be 38 Fahr. "In one of the boxes," writes Mr. Buckland, "the eggs nearly all contained living fish; in another they were 'blind,' that is to say, no embryo could be seen in them. In all the boxes there was a certain percentage of eggs which had turned quite white. Some of these white eggs presented a curious appearance—namely, a spot exactly the color of a strawberry, which covered a third of the surface of the egg."
The experiment was on the whole satisfactory, and proves that salmon-eggs may be kept in a healthy condition for 112 days or longer. It is still a question, however, whether the rivers of New Zealand are suited for the cultivation of salmon. Some years ago 1,200 trout ova were shipped to Victoria, and recently Mr. Buckland received from that colony a trout weighing 7 lbs. If salmon thrive equally well in Australasian waters, this essay in "practical natural history" will be productive of immense benefits to the British colonies in the South Pacific at no distant day.
New Theory of Boiler Explosions.—A late number of the American Artisan has a paper by Dr. L. Bradley, on "The Dissociation of Water by Heat as a Cause of Boiler Explosions," in which the author very well shows that such accidents are in many cases produced, not by tension of steam, but by the explosion of oxyhydrogen gas. Dr. Bradley in the first place states very clearly the history of the law of dissociation, or the separation of a compound body into its elements by the force of heat. Under atmospheric pressure the two elements of watery vapor, viz., oxygen and hydrogen, are dissociated at 1,298° Fahr. "If, therefore," says the author, "we heat a bar of iron to fully 1,298°, and place it over a globule of water upon an anvil, a blow with a hammer will elicit the detonation of a rifle; I have repeated this experiment often. The elements of the water dissociate by the heat, and instantaneously recombine in cooling, causing the detonation."
The degree of dissociation, as of evaporation, depends on the pressure: under four atmospheres (60 lbs.), the heat required for dissociation is 1,870° . But the question arises, If the vapor dissociates at these temperatures, why do not the gases instantaneously combine and detonate? The reason is plain: in the boiler the atoms at once become mixed with a volume of steam sufficient to render them inexplosive.
The condition requisite for the generation of explosive gas in a boiler is that vapor be in contact with a surface heated to 1,298°, or higher, according to the pressure, as we have seen. Now, this condition may occur in a boiler filled with water, owing to the property which that liquid possesses of assuming the spheroidal shape when in contact with a highly-heated surface. "It is, therefore, not difficult to conclude," says the author, "that, in case of very heavy firing, a thin film of vapor may form between the water and the boiler, and, when this is once formed, the heating of the boiler would be so rapid that nothing but the cooling process of dissociation, which would then commence, could save it from completely burning through."
Explosion would then occur whenever—
- The oxyhydrogen gas, as compared with the steam, rises to the explosive proportion; or,
- When the steam, by condensation, falls to the explosive proportion. To make explosion possible, the proportion of oxyhydrogen gas to vapor must be at least as 1 to 7.
Scientific Education in England.—Sir Josiah Mason, a manufacturer of Birmingham, is about to found a scientific college in that town on a most liberal scale. It is intended to afford thorough systematic scientific instruction, specially adapted to the practical, mechanical, and artistic requirements of that great centre of manufacturing industry. Systematic instruction is to be given in mathematics; abstract and applied physics; chemistry, theoretical, practical, and applied; the natural sciences, especially geology and mineralogy, with their application to mines and metallurgy; botany and zoology, with special application to manufactures; and physiology, with special reference to the laws of health. The English, French, and German languages will be taught, but mere literary instruction is excluded. No principal, professor, teacher, or other officer of the college, is ever to be called upon to make any "declaration as to, or submit to any test whatever of, his religious opinions," and the institution is to admit all persons "without distinction of age, class, creed, race, or sex," to the popular lectures; while the regular course will be open to qualified persons of all classes, "especially the more intelligent youth of the middle class." This Nature calls "one of the most princely gifts yet made to posterity in England by one of her wealthy sons."
The Hotchkiss Revolver-Cannon.—Some trials were recently made, says the Revue d'Artillerie, at the Satory Polygon, with a revolving cannon, invented by Mr. Hotchkiss, and intended for the Italian Government. The special object of these experiments was to ascertain the mechanical value of this engine. This new arm (whose calibre is 1½ inch) differs essentially from all other mitrailleuses hitherto brought before the public, particularly in this, that it discharges a small cast-iron shell with percussion fuse, the effects of which may be formidable at distances relatively considerable.
We will, at another time, present a complete description of this gun, but for the present must content ourselves with giving some details of the ammunition employed. This consists of a cartridge with shell attached. The cartridge proper consists of a soldered tube of tin, with one end closed to form a cup. This closed end is reënforced, within and without, by two iron caps, and fastened with three rivets to a broader iron plate, which forms the true base of the cartridge, bears the pressure of the gases, and affords a grip to the extractor. The percussion cap is fixed in the centre of this iron plate. The cartridge will hold 32 ounces of powder, with space for a thick felt wad between the latter and the projectile. The charge of powder employed at Satory was only 25 ounces, the unoccupied space being filled with two disks of brown paper, laid over the powder and covered with wadding. The shell, which has a total length of 22 calibres, has a jacket of latten covering a portion of its length, with grooves answering to the riflings of the gun. Its weight is 172 ounces, and it contains a charge of 15 ounce of powder. The whole cartridge, charged and primed, weighs 285 ounces.
The shell does not appear to be held tightly enough in the cartridge-case; it can be detached by the hand with but little trouble, and there is reason to fear lest, when charged cartridges are transported in boxes, the shells may be separated from their sockets.
To obviate all accidents, the revolver-cannon was set en batterie at about 100 metres, or 328 feet, from the butte, the shells being charged and provided with thin percussion fuses. At first the exploded cartridges, when withdrawn from the cannon, were not at once dropped by the extractor; but this slight defect was in a few minutes remedied, and, during the remainder of the experiments, there was no further difficulty in working the piece. The cartridges were greased before being used.
They suffered no injury from the discharge, and could be recharged and used over and over again. One had opened along the soldering, but had not been rent, nor had any gas escaped. It could be used again, on being soldered anew. Only one cartridge missed fire, and even this went off at the third trial. Only one of the shells also failed to explode. Nearly all of them went through the target, and only exploded in the butte. One, however, burst on striking the target, and one exploded within the gun-barrel; but this latter mishap is not necessarily to be attributed to any irregular action of its fuse, for the shells appear to have been badly cast, and one of the walls, oftentimes, by reason of the eccentricity of the central void, is extremely thin.
Six shots were fired in succession in 12 seconds, the cartridges being set in place one by one; then 15 cartridges in 15 seconds, with the use of boxes previously supplied with a certain number of cartridges. The fire might be kept up for some time at the rate of 60 shots per minute—equal to 66 pounds of cast-iron shot off in that space of time. The firing is very regular, and the sighting does not appear to undergo any notable variation.
Each shell breaks up into 12 or 15 fragments, large enough to produce mortal wounds at a certain distance from the point where they explode. Most commonly its bottom-piece (culot) separates from the rest without breaking, though lines of cleavage may have been made in it beforehand.
A notable drawback is the rapid fouling of the gun by the shells, which is manifest after the first few shots, and quickly grows worse. Doubtless this is attributable to the bad quality of the latten forming the jacket of the projectile.
We should say that the mechanism of Hotchkiss's revolving cannon works with certainty and regularity, and that its ammunition would do good service, were the shell better fastened in the cartridge. This shell is an article of difficult and delicate manufacture, and of a rather high price. The cannon would doubtless produce formidable effects at ranges approaching those of field-artillery, and the explosive properties of its projectiles give it a great advantage over all other mitrailleuses, since the aim can be regulated by observing the points where the shells fall.
Fertilization of Flowers.—Mr. Meehan last year exhibited, at the Philadelphia Academy of Natural Sciences, a pear having fibrous instead of granular flesh, and a tough rind like that of the apple. He accounted for these phenomena by the theory that apple-pollen had impregnated a pear-pistil. At the meeting of the Academy held January 21st he exhibited an ear of Indian-corn which serves to confirm his hypothesis. As soon as the "silk," that is, the pistils, appeared, the pollen in the "tassel" of a quite different variety of corn was set in a bottle near it, the plant's own tassel having been cut away some time previously. Soon this tassel was taken away, and replaced by another of a different species. The result was that each grain bore a resemblance to the grain of the two impregnating plants, the base having the color of the one, and the upper half the color of the other. Thus it is seen that one ovule may receive an impress from the pollen-grains of at least two separate plants, even though a considerable time intervene between the first and second impregnation.
Madeira as a Health-Resort.—That invalids, who visit distant climes in pursuit of conditions more favorable to health than they can find at home, are but too often led by false hopes, is an every-day observation. A writer in the London Times, who went out to Madeira last year for the benefit of his health, has proved the truth of this observation by his own experience, and labors to convince other invalids that they can find, nearer home, advantages every way superior to those enjoyed at Madeira. The temperature of that island is no doubt remarkably equable, the thermometer very rarely indicating under 60° or over 78°; but yet from the latter end of February up to the date of the writer's letter, the beginning of May, the weather was as unpleasant as could prevail even in England. During March there were keen, piercing winds, and occasional hot sun, and April was a succession of chilly, damp, and rainy days. Thus the patient is almost sure to lose, in the discomforts of spring, all the strength he may have gained during the summer and winter.
A Portuguese never condescends to let apartments, and the invalid must put up with the very imperfect accommodation of the hotels, where comfort and sanitation are entirely disregarded. The writer regards the Madeira climate as especially unfavorable to youthful invalids. Finally, it would appear that every obstacle is placed in the way of those who wish to return home from the island. The writer's conclusion is, that the chances of recovery for a consumptive are far better at home, surrounded by the conveniences and comforts of life, than in Madeira, where the only favorable condition is the climate, and where even that advantage is more than balanced by the storms of the spring season.
Lacustrine Dwellings in Germany.—The remains of ancient habitations raised on piles are of rare occurrence in Germany, and hence the discovery last year of the débris of such structures in the bed of the river Elster, near Leipsic, awakened a lively interest. The discovery was made by Herr Jentzsch, of the Geological Institute of Austria. The order of the visible strata at this point is as follows: At the base is found a layer of sandstone; on this a lacustrine clay. Both of these belong to the upper portions of the quaternary rock. In the clay are two beds containing the remains of plants, and among these are found leaves of the willow and oak, fruit of the Acer, and sundry other vegetal fragments. Above these occurs a layer of roots some inches in depth, which shows that the surface of the soil remained at this level for a considerable period. The uppermost layer, two to three metres thick, was produced by an inundation. The piles discovered by Jentzsch in the bed of the Elster are set in the clay and covered over with this silt. They are arranged in circles, with their lower ends pointed, and their upper extremities connected by horizontal ties of oak.
Among the animal remains found here are, the lower jaw of an ox, with its teeth, stags' heads, the long bones of some mammal yet undetermined, and shells of the unio and anodon. No traces of human remains have been found, though fragments of pottery and charcoal are met with; also two stone hatchets.
Industrial Occupations of Women.—The following notes of avocations followed by women in the United States, taken from the last census returns, give a curious exhibit of the extent to which woman is now invading provinces of industry which once were supposed to belong exclusively to the other sex: Agricultural laborers, 373,332; stock-herders and stock-raisers, 75; architect, 1; auctioneers, 12; barbers and hairdressers, 1,179; clergy, 67; dentists, 24; hostlers, 2; hunters and trappers, 2; lawyers, 5; livery-stable keepers, 11; midwives, 1,186; physicians and surgeons, 525; scavengers, 2; sculptors, 4; teachers, 84,047; whitewashes, 391; bankers and brokers, 15; barkeepers, 70; boat-hands, 30; canal-boat hands, 10; dray-drivers, teamsters, etc., 196; newspaper-carriers, 7; pilot, 1; undertakers, 20; bell-foundery operatives, 4; brass-founders, 102; brewers, 8; brickmakers, 14; carriage-trimmers, 32; charcoal and lime burners, 5; cigar-makers, 1,844; clock-makers, 75; curriers and tanners, 60; distillers, 6; engravers, 29; fishers, 35; gas-works employees, 4; gun and locksmiths, 33; printers, 1,495; shingle and lath makers, 84; tinners, 17; wood-turners and carvers, 44.
Effects of Freezing on Wine and Spirits.—Some experiments on the freezing of wines and spirits are recorded as follows by M. Melsens in the Comptes Rendus of the French Academy of Sciences. Brandy cooled to as low as minus 35° C. was pronounced exquisite, and some connoisseurs pronounced it all the mellower in proportion as the temperature was reduced. About -30° C., alcoholic liquors, containing 50 per cent, of absolute alcohol, become viscid, syrupy, and sometimes opaline. The author solidified spirits (cognac, rum) at -40° and -50° C., and says that if they be then taken as ices, or sherbet, with a spoon, it is surprising what little sense of cold there is. A spoonful of this ice when placed on the tongue appears to be less cold than ordinary ices, and many persons who have tasted such frozen cognac or rum could scarcely bring themselves to believe that they had on their tongues ices which might be served on dishes of frozen mercury. In fact these ices must be reduced to -60° C. before the one who tastes them pronounces them "cold;" and scarcely ever will any one pronounce them "very cold." The lowest temperature at which M. Melsens experimented with these frozen alcoholic liquors was -71° C. If a considerable quantity at that temperature be taken into the mouth, the effect is like that of a spoonful of soup a little too hot. In this case a wooden spoon must be employed, one of metal producing a blister. Placed upon the dry forearm this solid eau de vie produces a slight cauterization, without burning, as would a fragment of solid ether or carbonic acid.
The author's experiments on wines were undertaken with a view to discover the means of preserving them. On placing them in a vessel surrounded with a freezing mixture, they were reduced to the condition of a mass of ice-crystals permeated with a colored fluid. This he transferred to a wire sieve, and, by agitating it there, expelled the liquid. The ice on being melted was found to be tasteless, with the merest traces of alcohol. Thus the percentage of alcohol in the wine when deprived of its water is increased, and its keeping quality greatly improved. The author suggests freezing as a method of improving the body of light wines, which otherwise will not bear transportation, and says that if in France wine-growers will adopt the plan of heating their wines in order to check the "diseases" to which they are subject, and of freezing them, so that they may keep, the trade in wine will be rendered far less fluctuating than it now is. It will be possible to keep on hand a large quantity of wine, so as to offset the effects of bad harvests.
What Darwinism means.—From our esteemed contemporary, the Lens, of Chicago, we take the following correction of current misapprehensions as to the true meaning of Darwinism: "Prof. Edward S.Morse," says the Lens, "delivered, early in March, two lectures in Chicago, the one with the title 'From Monad to Man,' the other on 'Evolution.' In the lecture on 'Evolution' Prof. Morse makes two statements worthy of special note. In the one he alleges that the prejudice against Darwin, and the ridicule so freely expended upon him, are based on an entire misapprehension. Darwin has never taught that man is a development from a monkey, or from any lower species. Nor is there any thing in his philosophy that even admits of inference to this effect. He simply teaches, or suggests the probability, that man or monkey is simply 'evolved' from a lower basis of life. The several streams, all starting from one source, as they branch—the one goes to the monkey, and there stops; and the other to man, and there stops. It is not Darwinism that man himself, or the monkey itself, shall keep on till there is development into something higher and different. The other statement was to the effect that science deals with phenomena, not with the intelligent cause. It notes and defines law; has nothing to do with the creator of the laws. Science, therefore, cannot take the place of religion. And when the man of science passes from the law to the author of law, he drops the character of scientist and assumes to teach religion. The scientist is not, therefore, censurable for restricting himself exclusively to the phenomena, making no reference to the power lying behind phenomena."
A Hoarding Bird.—A writer in Hardwicke has discovered in the nuthatch, or nutpecker, the habit of laying up in its harvest-season a store of nuts for a winter provision, a characteristic which has been hitherto observed, as the writer remarks, in no other birds save tame individuals of the family Corvidæ. One day last September a nuthatch was seen to light upon a potato-hill, and there to drop something, which it drove into the earth with repeated taps of its beak. On investigation a nut was discovered there, and soon after six other nuts were found buried in close proximity to it. Again, so late as November 1st, the same bird was seen to bury a nut in a flower-bed, and, in the depth of winter, if watched, he will be found to visit frequently his hoards, taking with him, from time to time, so much as he needs for his present wants.
Artificial Respiration in Snake-Poisoning.—The publication of Dr. Fayrer's work on the Thanatophidia of India has led to a very active investigation of the subject of snake-poisoning. The author himself has made several experiments on the efficacy of artificial respiration as a means of counteracting the venom. In one of these he kept the heart beating for nine hours after the development of fatal symptoms. The heart then failed only from imperfect respiration carried on in the cold. If there is an analogy, as Dr. Fayrer supposes, between snake-venom and curare, there is every reason to expect that the remedy (respiration) which is effectual in antagonizing the latter will be equally effectual against the former.
Dr. Richards, of Balasore, thus details an experiment, made by himself, where the heart's action was kept up for 24 hours and 85 minutes: "This is, perhaps, the most remarkable case of its kind on record. The dog was, to all appearances, dead when the artificial respiration was commenced. Two hours and a half later convulsive movements were excited by the application of the galvanic current, but at seven o'clock there was no response, and the body of the dog was cold. At this time the eyes presented a glazed appearance, being perfectly dry. The pupils were dilated, and the heart was beating feebly. Had artificial respiration been now stopped the heart would have ceased to beat almost at once."
At noon the next day the dog appeared as if it would recover. "The eyes had lost the glazed appearance, lachrymation was restored, and there were winking of the lids on dropping water into the eye, attempts at deglutition when water was put into the mouth, and the heart was beating vigorously."
As artificial respiration must be kept up for hours, or even for days, Dr. Fayrer recommends the use of a special apparatus for this purpose, to be worked by steam.