Popular Science Monthly/Volume 13/May 1878/Popular Miscellany
The Growth of Photography.—At one of the public lectures recently given under the auspices of the New York Academy of Sciences, Prof. Charles F. Chandler sketched the progress of photography during the last hundred years. The first authentic record of pictures made by solar agency he finds in Cooper's "Rational Recreations," published in 1774, where an account is given of the marking of bottles by silver salts. Next came Scheele's experiments on the effect of exposing to light paper sensitized by the same salts. The first genuine sun-pictures were probably produced by Bolton and Watt, who were followed by Humphry Davy and Wedgwood. Still, down to the beginning of the second quarter of the nineteenth century, photography had not advanced beyond the stage of producing images of plant-leaves laid on sensitized paper, and exposed to light. These images, crude as they were, soon disappeared on continued exposure of the paper to the light, for as yet no means of fixing the photograph image had been discovered. Niepcé studied the subject experimentally for nearly fifteen years, without any very encouraging results, but in 1824 he associated with himself Daguerre, who in 1839 announced to the world his discovery of a method of producing permanent sun-pictures. Dr. Draper, of New York, added sundry important improvements to Daguerre's method. Fox-Talbot produced the first silvered-paper photograph, which was the germ of the modern sun-picture. The great development came in 1841, when Schönbein discovered gun-cotton. Cotton, he found, when exposed to nitric acid, becomes explosive, and soluble in a mixture of alcohol and ether. The discovery of this latter property was the foundation of the common photographic process, where a film of collodion, sensitized by silver iodide, produces the "negative" image, from which thousands of pictures may be struck off. It was stated by Prof. Chandler that Albert, a photographer of Munich, and Edward Bierstadt, of New York, are engaged in perfecting a process for printing photographs in colors.
The Development of Botanical Science.—The progressive development of botanical science is forcibly exhibited by the Belgique Horticole, in a numerical statement of the different species of plants named in sundry ancient documents, and now ascertained by botanists. Thus, in the Bible, we are told, about fifty plants are clearly determined, while about as many more are mentioned in more general terms. Hippocrates mentions 234 species, Theophrastus about 500, Dioscorides over 600, and Pliny 800. In the sixteenth century Conrad Gerner names 800, Charles de l'Escluse 1,400, Dalechamps 2,731, and Gaspard Bauhin 6,000. In 1694 Tournefort describes 10,146 species. He was the first to class the species of plants into genera, of which he reckoned 694. In the eighteenth century Linné defined 7,294 plants, distributed in 1,239 genera. In 1805 Persoon's "Synopsis Plantarum" included nearly 26,000 species, and in P. de Candolle's "Elementary Theory of Botany" 30,000 species are said to be known scientifically. Stendel's "Nomenclator Botanicus" (published in 1824) contains 78,000 names of plants. Loudon's "Hortus Britannicus" (1839) enumerates 31,731 species in 3,732 genera. According to Endlicher (1840), there were 6,895 known genera in the vegetal kingdom, which number is increased to 8,931 by Lindley in the year 1853. In 1863 Bentley estimated the known species at 125,000. The Belgique Horticole thus classes the species now known:
or, in all, about 120,000 species distributed among 8,000 genera. The species actually cultivated number 40,000, and these are true botanical species, not simply races or varieties.
Facts about the So-called "Rain-Tree."—For some months there has been circulating in the newspapers a notice of a tree found in Northern Peru, the "rain-tree of Moyobamba," from the trunk of which, as the story runs, "water may frequently be seen to ooze, falling in rain from the branches in such quantity that the ground beneath is converted into a perfect swamp." The facts with regard to this "rain-tree" are stated as follows by Mr. Spence, the traveler, in a letter to Mr. Thiselton Dyer, which the latter has communicated to Nature. The tree is not a myth, but a fact, though the current story is not quite exact. Mr. Spence first witnessed the phenomenon in question in September, 1855. On a certain day, about seven o'clock in the morning, while in latitude 6° 30' south, longitude 76° 20' west, he found a "lowish, spreading tree, from which, with a perfectly clear sky overhead, a smart rain was falling. A glance upward showed a multitude of cicadas sucking the juices of the tender young branches and leaves, and squirting forth slender streams of limpid fluid." The tree belonged to the acacia tribe, but Mr. Spence was informed by his native attendants that almost any tree, when in a state to afford food to the nearly omnivorous cicada, might become, pro tempore, a Tamia-caspi, or raintree. Afterward, he himself verified this fact more than once. "As to the drip from the tree causing a little bog to form underneath and around it," writes Mr. Spence, "that is a very common circumstance in various parts of the Amazon Valley, in flats and hollows, wherever there is a thin covering of humus, or a non-absorbent subsoil, and the crown of foliage is so dense as to greatly impede evaporation beneath it."
Clearing Land with Dynamite.—A severe storm of wind having blown down a number of large trees on the estates of the Earl of Stamford and Warrington, recourse was had to the use of dynamite for the purpose of breaking up the roots, that being esteemed the most expeditious mode of removing those incumbrances. The first experiment was made on four very large elm-roots. An auger-hole, one and a half inch in diameter was bored in each, and charged with eight dynamite cartridges, which, on being exploded, shivered the roots into fragments suitable for firewood. The second experiment was on two huge oakroots. These were simply charged by placing a few cartridges of dynamite in natural crevices of the roots, without any auger hole. The charges were exploded, and the roots blown to pieces of manageable size. Next, an auger-hole was bored in each of seven oak-roots, and charged with two cartridges each, the result being that all were broken up. The fourth experiment was on an extraordinarily large ash-root, the great fangs of which were lying undisturbed in the ground. Underneath this a number of crowbar-holes were made and charged with dynamite. The fuses were all cut the same length and fired simultaneously, blowing the whole mass out of the ground.
Color-Blindness.—In an article on "Defective Vision considered in its Relations to Railroad Management," published in the Chicago Railway Review, Mr. Thomas F. Nelson, optician, remarks as follows on the phenomenon of color-blindness: "This defect but rarely assumes the form that would be termed absolute color-blindness, or want of any sensation of color. Where this form is perfectly developed there is generally a sharp, well-defined appreciation of differences between light and shade, or even between the finest grades of apparent brightness or intensity; but recognition of color is entirely wanting, there being no distinction whatever between different colors having the same degree of intensity. A curious fact might be noticed in this connection, that these defects are but rarely found in women.
"The more common form is that caused by the absence of perception of one of the three fundamental colors. These are mentioned in the order of their comparative frequency, viz., where the elementary sensation corresponding to red is wanting; next, the absence or imperfect perception of green, and third of blue. It will be noticed as a remarkable fact that the first two mentioned are now used to make up the entire code of railway-signals, and that this defect for red occurs more frequently than for any other color. This is an item of the greatest importance in railway and vessel management, since red is almost always used for the danger-signal. To add still further to the deceptive and dangerous character of the defects, I have, in the course of my experiments, found a number of persons who were unable to distinguish between the primary colors at night, while their perception or sensation of color by daylight was apparently perfect. Again, I have found another anomaly which, until it has been more thoroughly investigated, and the real causes that produce it are understood, I shall designate as a form of color-blindness, although I am in doubt myself as to its dependence upon any of the principles that enter into that defect; this is an inability to distinguish between or to recognize the primary colors at certain distances, varying more or less in individuals. This was found to be the most difficult of all defects to detect in the various cases I have examined, amounting to some nine or ten, in the regular course of my business as optician during the past three years. I have found no two of them at all alike except in general results.
"I have kept records of various accidents that have occurred, both upon land and water, during the past few years, and I have gathered such information about some of them as I could get outside of official sources—often I was unable to get any of any value, but I am convinced beyond a doubt that a large proportion of them could have been traced to this defect for a correct solution as to the primary causes of the accident. The query has been made, that if these defects in their various forms are as numerous and of such a dangerous character as has been shown, how can we account for such a comparatively small number of accidents occurring which might be charged to them? I have attributed it to the high average intelligence and acquired cautiousness of engineers and pilots as a class. They have become so accustomed to be on the lookout for danger that their suspicions are easily aroused, which creates a sort of instinct that governs their actions, and they do not recognize but that their perceptions are correct."
Sewer-building.—The general principles of sewer-building are, says the Polytechnic Journal, that each day's influx should be promptly passed out by natural flow or flushing, and not allowed to deposit sediment. The alignment should be good, especially at the bottom; the descent should be uniform, and the interior surface smooth, so as to reduce friction and not to cause clogging; the walls should be absolutely impervious, and the suction such as will cause the most rapid possible flow, with a minimum of sewage. Rapid flow being essential, smooth interior walls should be provided; mortar projecting from the joints of a brick sewer markedly impedes the flow and arrests putrefiable matter. A flat-bottomed sewer is the worst form as regards the velocity of the flow; a circular bottom is better; an egged-shaped section, with the point downward, permits of a minimum current flushing and cleansing the bottom. In brick sewers the mortar, constantly moist, must sooner of later succumb to the disintegrating action of the matters passed through it, and the whole line gradually passes into the condition of a sieve, allowing the liquid portions of the sewage to pass through it and to saturate the subsoil, but retaining the solids. From the consequent saturation of the soil result contagious fevers. Hence vitrified clay pipes are now almost universally employed. The "slip" glazing applied to these pipes resists the severest chemical action of sewage-water. The "slip" glaze is produced by dipping the unbaked clay into a mixture of "slip-clay" or Albany earth and water, which, under a white heat continued from twelve to thirty hours, produces a vitreous and very durable silicious surface upon the wares.
Remarkable Land-Slides.—Bear-Tooth Mountain is one of the most prominent landmarks in Northern Montana; it is plainly visible from Helena, thirty miles distant. It presents, or rather used to present, the appearance of two great tusks rising hundreds of feet above the general contour of the mountains. One of these tusks, the smaller one, which was fully five hundred feet high, three hundred feet in circumference at the base, and one hundred and fifty feet at the top, was recently dislodged from its place and precipitated into the valley below. A few weeks since, according to the Helena Independent, a party of hunters chasing game several miles north of the Bear Tooth heard a rumbling sound and felt a quaking of the earth, which they took to be a veritable earthquake. But, as the sound was not repeated, they soon forgot the occurrence, and continued their chase till they came to the vicinity of the Bear Tooth. What was their surprise to find that the stupendous mass of the eastern tusk had been dislodged, sweeping for a quarter of a mile through a forest of heavy timber, and overwhelming with its débris the ground round about! Virginia City, in the same State, is gradually slipping down the mountain-side on which it is built. The movement is gradual, and imperceptible at the surface. A water-main recently uncovered was found telescoped for the space of one foot, and otherwise injured. A fissure has been traced in the ground on the western side of the town; on one side of this the ground is three feet higher than on the other.
The Death of a Generation.—A writer in an English magazine studies from birth to death the march of an English generation through life, basing his remarks on the annual report of the registrar-general. The author singles out, in imagination, a generation of one million souls, and finds that of these more than one-fourth die before they reach five years of age. During the next five years the deaths number less than one-seventh of those in the first quinquennium. From ten to fifteen, the average mortality is lower than at any other period. From fifteen to twenty the number of deaths increases again, especially among women. At this period, the influence of dangerous occupations begins to be seen in the death-rate. Fully eight times as many men as women die violent deaths. The number of such deaths continues to rise from twenty to twenty-five, and keeps high for at least twenty years. Consumption is prevalent and fatal from twenty to forty-five, and is responsible for nearly half the deaths. From thirty-five to forty-five the effects of wear and tear begin to appear, and many persons succumb to diseases of the important internal organs. By fifty-five the imagined million has dwindled down to less than one-half, or 421,115. After this, the death-rate increases more rapidly. At seventy-five, there remain 161,124, and at eighty-five, 38,565. Only 202 reach the age of one hundred. At fifty-three, the number of men and women surviving is about equal, but from fifty-five onward the women exceed the men.
Setting Tires with Hot Water.—The use of hot water in place of fire for expanding tires may not be new, but it is less common than it ought to be, if we are to accept as accurate the results said to be obtained in the workshops of the Moscow-Nizhni Railroad, in Russia. There an iron tank, one-fourth filled with water, is fixed near a stationary boiler, from which a steam-pipe is led through it, capable of heating the water to 212° Fahr. Into this the tire is plunged by means of a portable crane, and, after an immersion of from ten to fifteen minutes, is taken out and immediately placed on the wheel. The allowance for shrinking—in other words, the difference between the diameter of the skeleton and that of the tire—is 0.75 millimetre to a metre. This is ascertained by gauges of great accuracy; and, if it be deviated from, the tire will either be loose after cooling, or too small to get on the wheel. When fire is used, the tire can never be heated equally or cooled equally in all parts, and, in consequence, is sure to be more or less oval in form, which is not the case when hot water is employed. The officials of the railroad named above made a comparison of the two methods, from which it appears that, during a six years' trial of fire-shrunken tires, 37 per cent, ran loose, and 5 per cent, were broken; while, during a three years' trial of water-shrunken tires, less than one per cent, ran loose, and only a single tire was broken.
Distribution of Prairie and Forest.—Many are the theories which have been offered to explain the distribution of prairie and forest. The continued existence of the prairies of the West has been attributed to the annual fires; to the nature of the soil and its underlying rock; to deficiency of rainfall; finally, to deficiency of winter rains and snow. The contrary conditions would, according to these theories, favor the production of forests. Prof. J. E. Todd, who, in the American Naturalist, discusses this problem with special reference to South-western Iowa, offers a very ingenious theory, and one that certainly appears to account for the phenomena observed by him in the above-mentioned region. He finds that—1. In the hill-regions where the slopes are inclined from 5° to 10°, timber occurs mostly on the northern slopes, just south of creeks flowing east or west; it occurs a little less frequently on western slopes, east of creeks flowing north or south; 2. In the bluff-region, where the slopes are from 10° to 45°, just east of the bottom-lands of the Missouri, timber is found over most of the surface. This belt of timber-land is usually bounded on the west by the crest of the most western ridge of the bluffs, leaving the slopes facing the bottom-land bare, except when a lake, slough, or stream, comes close to the base of the bluffs, or where the bluff-side is deeply furrowed by ravines; 3. In the low alluvial valleys, timber is found along the streams, usually in narrow strips, and generally wider on the east and north banks; the rest of the bottom-land is destitute of trees and bushes. According to the author, constancy of moisture is the condition sine qua non of forest-growth; and, 1. This constancy of moisture must be in one or both the media in which the trees are to exist—the soil or the air; 2. It is plain that moisture of soil will be more constant on northern slopes than southern, the former being less exposed to the sun's heat. In the spring, and after showers, the northern slopes dry up more slowly, and, at certain degrees of humidity of the air, the moisture given off by the southern slope of a hill may be condensed by the northern. These and other like considerations may perhaps account for the timber occurring on northern slopes, while it is nearly absent from southern; 3. The fact that the prevailing winds of Southwestern Iowa in spring and summer are westerly may perhaps explain the preponderance of timber-areas on the east banks of the streams flowing south; and this, combined with the increased roughness of the surface, may also go far toward explaining the timber-belt of the bluff-region; 4. It remains to explain the distribution of timber and prairie in the alluvial valleys. Here layers of clay prevent the ready drainage of many parts; these conditions render much of the surface too wet (for trees) at all times, while other places are too wet in spring and too dry in summer. On the other hand, the occurrence of trees along the streams and on ridges along old channels may be explained partly by the inequality of surface, making the drainage of surplus water possible, so that moisture around the roots is more constant than elsewhere on the bottoms.
More about the Agricultural Ant.—While visiting Texas last summer, the Rev. H. C. McCook attentively studied the habits of the agricultural ant (Myrmica molefaciens). His observations are, for the most part, strongly confirmatory of the statements made by the late Dr. Lincecum; but he also adds to our knowledge of these interesting insects a number of new and interesting facts. Mr. McCook has published, in the "Proceedings of the Academy of Natural Sciences of Philadelphia," a general preliminary statement of his results, intending soon to treat the subject more fully. He carried on his observations in the vicinity of the city of Austin, where the soil is black and sticky, varying in depth from three feet to a few inches. The formicaries of the agricultural ants are commonly flat, circular clearings, hard and measurably smooth, aptly called "pavements" by Lincecum. A few of them had in the centre low mounds, a few inches in height, and two or three in diameter. The formicaries vary in width from twelve feet to two or three feet. They are invariably located in open sunlight. The process of making a clearing strongly suggested the modes of pioneers in a forest—spires of grass taking the place of trees. The chain of evidence that determines these ants to be true harvesters in as follows: 1. Workers were seen gathering seeds and carrying them into the formicaries through the central gates; 2. The same seeds were found in granaries within the opened formicaries; 3. The seeds, with outer shell removed, were found in other granaries; 4. The ants were found carrying out shells to the refuse-heaps. The author's opinion is, that these ants do not plant seeds on purpose, but that they carefully preserve on the outer margin of the clean space the growths which arise from seeds dropped accidentally. To the question whether there is anything like a systematic direction of the labors of the ants by the queen or the major-workers, Mr. McCook replies that the queen seems to have nothing to do but to replenish the population of the community; her life is spent mostly underground. No "officers" could be seen, and each ant acts independently. The worker-majors act constantly as sentinels, and once or twice was observed what appeared to be, on their part, an effort to aid the harvesters in gathering seeds. The entrances to the interior of the formicary are circular openings or gates at the surface, connecting with tubular galleries which lead to the granaries. These granaries consist of rooms of a more or less oval shape, one above another, after the manner of floors in a house. The rooms are about half an inch in height, with hard and smooth roofs and floors. Similar rooms are employed for nurseries of the young. The rooms of each story, as also the different stories, are connected together by galleries. The author gave examples showing strong intelligence in separating white meal from arsenic, with which it had been mixed, and of the refusal of poisoned molasses.
Birds' Eggs and Birds' Nests.—There exists a curious relation between a bird's mode of nesting and the color of its eggs. The circumstance is noted in the Bulletin of the Nuttall Ornithological Club by Mr. J. A. Allen, who observes that nearly all birds that nest in holes, either in the ground or in trees, lay white eggs. As instances of this fact may be cited, the woodpeckers, kingfishers, bee-eaters, rollers, hornbills, barbets, puff-birds, trogons, toucans, parrots, paroquets, and swifts; while only occasionally are the eggs white in species which build open nests. A few exceptions are noted by the author to the rule, according to which only white eggs are laid in open nests; these are owls, humming-birds, and pigeons. On the other hand, in only two or three small groups of species that nidificate in holes are the eggs speckled or in any way colored. Wallace, it will be remembered, has endeavored to show that the form of nest is, as a rule, correlated to the color of the female bird: if the color is brilliant or in any way striking, the nest is concealed; and vice versa, if the female is inconspicuous in color, the nest is open. Mr. Allen, in the paper from which we are quoting, calls attention to the many weak points of Wallace's theory, and asserts that a more uniform correlation exists between color of eggs and style of nest than between the two members of Wallace's correlation. Mr. Allen, however, does not care to formulate a "law" upon the basis of the facts stated above, the exceptions being, as he says, too numerous to consist with the relation of cause and effect.
Subterranean Water-Courses.—It often happens, in years of great drought, that the waters of the Danube, near its source, nearly altogether disappear in the fissures and holes in the bed of the river. The proprietors of works situated farther down-stream have frequently closed these subterranean passages, to avoid losses of water. But other manufacturers, owning works on the Aach, a tributary of Lake Constance, a few miles distant from the Danube, and at an elevation some 150 metres less, contended that these holes and fissures in the bed of the Danube open into water-passages connecting with the source of the Aach; hence they applied to the courts for an injunction to prevent the stopping of these outlets. To test the truth of this theory of the Aach water-supply, 10,000 kilogrammes of common salt was thrown into the Danube at the point where it gets lost. This salt reappeared in the water of the source of the Aach. Another experiment consisted in mixing fluoresceine with the Danube-water at the same point. On October 9th, at 5 p. m., about fifty litres of this dyestuff was poured into one of the openings in the riverbed. On the morning of October 12th, the observers stationed at the source of the Aach perceived the coloration of the water, which was of an intense green. The color grew more and more intense till the evening of October 12th, and disappeared about 3 p. m. of the 13th.
A Bird-eating Trout.—A correspondent of Land and Water tells a well-accredited story of a trout caught in the act of swallowing a sparrow which it had seized. The trout had been kept for some time in an open shallow well or spring, and had become very tame. In the well was a flat stone, one end of which projected above the water. On this small birds would alight to drink, and the villagers suspected that more than one of them had fallen victims to the trout's rapacity. This surmise proved to be correct, for, one day while the owner of the well was passing with some friends, a splashing in the water caused them to turn and look. There was the trout struggling hard to gulp his prey. One of the spectators fearing that the fish would be choked by the wing feathers, thrust his hand into the water, and caught hold of them. But the trout, unwilling to surrender any part of his prize, held on resolutely, and the feathers had to be taken from him by force.
Meteorological.—In the eighth of Prof. Loomis's papers on Meteorological Phenomena, published in the American Journal of Science for January, with a view to determine the circumstances under which storms originate, the author takes all the instances in which the barometer fell below 29.25 inches at any station, Mount Washington and Virginia City excepted, during a period of twenty months from September, 1872, to May, 1874. The number of instances was 148, and corresponds to 44 different storms. Two-thirds of these storms had their origin north of latitude 36°, and one-half upon or very near the Rocky Mountains. Two of them came from the Pacific Ocean, three from the Gulf of Mexico, one from near Cuba; others were widely distributed in Wyoming, Dakota, Colorado, and elsewhere. The first stage in each of these storms was the development of an area several hundred miles in diameter, over which the barometer was about thirty inches, with areas of high barometer on both the east and west sides, a thousand miles distant. These areas of high barometer are one of the most important causes of the storm which succeeds. From this cause there arises a movement of air toward the central area which is relatively one of low barometer. The air thus in motion is deflected to the right by the earth's rotation, giving rise to the well known rotary motion of air during a storm's progress; there also occurs a diminished pressure in the central portion, and an upward movement of the air. The upward-rushing air carries with it large amounts of aqueous vapor which is condensed into rain. By the condensation of the vapor, heat is liberated, causing expansion of the air, and more violent inward movement of the wind. The rainfall thus tends to increase the force and violence of the storm, and invariably occurs when the storm is at its height. Heavy rains usually occur eastward of the storm-centre—that is, eastward of the area of lowest barometer—and usually diminish when the centre has passed. The author says, "I have found no instance of violent storms which was not attended by considerable rainfall, but the rainfall is to be considered as a result, not the cause of the first movement of the wind."
It was shown, in a former article, that storms have a forward motion, which is usually a little north of east. No sooner is a storm-centre formed than it begins to change its position. The storm's movement seems, with few exceptions, to correspond with that of the atmosphere, the average annual progress of which is from west to east. Prof. Loomis says that on the west side of a storm a pressure occurs, resulting from the cause which determines the general circulation of the atmosphere, and which exists whether a storm occurs or not. A storm disturbs the atmosphere chiefly in its lower portion; in the upper portions the general atmospheric movement goes on. The depressions of the atmosphere on the west side of a storm are from these conditions filled up, so that the barometer is continually rising closely in the rear of a storm, but as continually falling as before explained, just eastward of the storm-centre. It is a matter of common observation that, when a storm-centre is passed, high barometer and clear air are close at hand. Other conditions of a storm's progress are presented, and the interesting fact developed that high barometer, east and west of a storm-area, remains unaffected by the tempest that is raging between those areas—whence Prof. Loomis infers that the air inflowing in the storm and rising at or near its centre flows outward at a considerable elevation to the areas of high barometer, having been deprived of its aqueous vapor. It thus appears that a vertical circulation is going on during a storm's progress.
Snake-Affection.—Most people will prefer knowledge at second hand of the playfulness and affection of snakes, to personal tests of the existence of such qualities. Not so a correspondent of Land and Water, who, having got possession of a harmless snake of the species Natrix torquata about twenty-eight inches in length, adopted it as a pet. This snake took great pleasure in passing in and out again and again between the fingers of its master. It was only necessary to hold the hand in the open box, when he would at once commence to glide between the fingers, always turning round sharply the instant its tail was free, and resuming its journey in the contrary direction. The process of shedding the skin is worthy of observation. The snake lies in a sluggish state for several days. The bright eyes become dull and fishy, and the skin loses its glossy smoothness. In time a slight break appears to run in the line of demarkation between the mucous membrane of the mouth and the outer skin, along the edge of the lips. In a few hours the crack appears to widen, and the skin to dry and curl over at the edges. Soon after this, in the present instance, the snake passed through a wisp of straw provided for this purpose in his box, and the skin was stripped off in one piece. The animal was now as active as a kitten, and as hungry. He quickly swallowed a , whose cries were heard after it had passed into the snake's stomach.
A Magnetized Spider.—In a communication to the Academy of Natural Sciences of Philadelphia, Dr. John Vansant treats of the influence of magnetism on living organisms, and describes at length one experiment with a spider, which was killed by the magnetic emanation. The magnet employed was a small steel one, of the U-shape, the legs of which were about two and one-half inches long by one-half inch wide and one-sixth inch thick, the distance between the poles being about one-quarter inch. Having noticed a small spider actively running along the arm of his chair, he brushed it off upon the carpet, where it began to run, but was somewhat impeded by the roughness of the fabric. He now slid the magnet along the carpet, following after the spider, till it was between the poles. The animal almost instantly stopped, and in a few seconds was motionless; but, at the end of two or three minutes, it began slowly to move its legs and elevate and depress its head. At the end of five minutes the spider was quite still. After the lapse of ten minutes Dr. Vansant covered both spider and magnet with a tumbler. On the expiration of two hours, he removed the glass and observed the spider with a magnifying-lens. It was apparently dead. The author states that he has killed spiders and other small animals, as worms and insects, as well as some plants, by magnetism, at various times during the past eight years, but never before succeeded in destroying the life of a spider so quickly, and without touching it frequently, though lightly, with the magnet. In the present instance he did not touch the animal at all.
Waste of the Locomotive-Whistle.—Persons residing in the country near any of the great railway lines will heartily approve any effort made toward suppressing the nuisance of locomotive-whistles. A writer in the Railroad Gazette remarks as follows on the wastefulness of this practice: "A simple toot or two," he writes, "in cases of emergency, to warn some one from the track, or as a signal for brakes, would seem to be the only legitimate use of steam in the way of whistles. And yet, of the twenty or more trains which daily pass my residence, I notice that nearly one-half make a regular practice of blowing their whistles some twenty rods at a time, and some half a dozen times within as many miles; and their safety-valves also seem to be at work most of the time. It would be interesting to know exactly what percentage of the fuel is wasted in this way. If the coal-bunks upon their tenders were made so as to let a bushel of coal drop on the track every ten miles of their progress, the waste would then become so manifest, no doubt, that it would be attended to at once. If one train can be run without the use of the safety valve or whistle, another can be so run, with the exercise of an equal care and vigilance on the part of the engineer and fireman. This matter of waste at the safety valve and whistle seems to rest entirely with the men upon the foot-board of the engine; and, as they prize their good standing as engineers and firemen, they should attend to it."