Popular Science Monthly/Volume 22/March 1883/Popular Miscellany
Experimental Demonstration of Ohm's Law.—An interesting experimental demonstration of the truth of Ohm's law was recently given by Professor Alfred M. Mayer, of the Stevens Institute of Technology, before the New York Electrical Society. This law, as is well known, affirms that in any electrical circuit the current flowing varies directly as the electro-motive force and inversely as the resistance, or, in symbols, C R, where C is the current, E the electro-motive force, and R the resistance of the entire circuit, including that of the generator. To demonstrate the truth of this law, it is only necessary to show that, the resistance remaining constant, the current increases in the same ratio as the electro-motive force when this is augmented; or that, the electro-motive force being mainlined constant the current varies in the same ratio as the resistance as this latter is raised. In Professor Mayer's experiments the current was measured by means of a Thompson reflecting galvanometer—a delicate instrument in which the deflections of the needle are multiplied to any desired extent by means of a beam of light, reflected from a small mirror attached to the needle, which is received upon a screen. The novel feature of Professor Mayer's demonstration consisted in his mode of obtaining the current so that the electro-motive force could be known with great accuracy, and readily varied. This consisted in generating it by means of the movement of a coil of wire along a bar-magnet. The electro-motive force of the current so produced depends upon the number of lines of magnetic force cut by the moving coil in a unit of time, so that this can be varied by varying the speed with which a given coil is moved, or, the speed remaining the same, by varying the number of coils. Professor Mayer resorted to the latter measure, his apparatus consisting simply of an upright bar-magnet over the end of which a loop of wire could be slipped, the distance which this could slide being limited by a stop. The movable coils consisted of the same lengths of copper wire, in which there were taken one, two, or more loops, the resistance of each of these pieces being the same, so as to maintain that of the complete circuit constant. The coils were placed over the upper end of the magnet, and carried down until they rested upon the stop, the needle of the galvanometer brought to the zero of the scale, and then the coil pulled off the magnet with a quick motion. The deflection of the needle indicated a variation in the current in proportion to the number of loops of wire used, and when the resistance was varied in proportion to the amount of this variation. A better form of the apparatus is one in which the coil, instead of being moved by hand, is drawn up quickly by a spring, when it is released by the pulling of a trigger. With this, Professor Mayer is at present studying the development of magnetism in eloctro-magnets.
More about the Lignified Snake.—Doubts are expressed, in a paper recently read by Professor C. V. Riley before the Biological Society of Washington, as to the so-called "lignified serpent" of Matto Grosso, Brazil, which was described and illustrated in the November number of the "Monthly," being really a serpent at all; Professor Riley rather believes the formation to bo the burrow of the larva of some beetle, filled up with excrement and rudimentary fiber, as such burrows commonly are filled. In support of his view he makes the points: that the object in advance of the so-called reptile's head to the unimaginative eye appears, not like an insect larva, but like a simple knot, similar to two knots which appear in the body of the more prominent formation; that the diameter of the formation is greatest at the point where the relief ends, as would be the case with a larva eating its way from the point corresponding with the "head" of the "serpent" and growing as it advanced toward the "tail"; that the first curve, which, on the serpent theory, the animal must have made in forcing its way under the bark, is so abrupt and the relief so doubled upon itself that a snake could not make such a bend without breaking its vertebræ; that the cephalic plates and scales are imaginary; that the curves shown, though natural to a burrowing larva, are not natural to a snake forcing itself into so confined a space; that the woody formation of the relief indicates a burrow beneath the larva, and not the forcing of anything between the bark and the wood, for such forcing would have loosened the bark for some distance on either side of the relief, and a forcing of the kind supposed could not take place without interference with the growth or soundness of the tree; that the granular appearance to be seen along the sides of the specimen and the fibers observable are just such as an insect-larva would leave, and can not be accounted for on M. Ollivier's hypothesis; that the animal matter in the center of the body may be accounted for as arising from the exuviæ and excrement of the larva; and that the work of human hands in heightening resemblances, particularly about the head and eyes, can be detected. The whole question, finally, could be readily settled by careful section, which would show traces of vertebræ or phosphate of lime along the vertebral line if there really were a serpent. Professor Gray, in the January number of the "American Journal of Science," suggests two explanations as more probable than that which depends upon the snake. One is, that the snake-like body is of the nature of a root, an aërial root, like those of a Clusia or a Ficus, which was making its way between bark and wood, and that the supposed larva is an incipient root of the same kind. The other, which was proposed by Professor Wadsworth, of Cambridge, while examining the specimen along with Professor Gray, "and is to be preferred," "supposes that the sinuous course is the track of a wood eating larva or some kind of insect, the burrowing of which had not destroyed the overlying fiber; consequently the new growth filling the space (except at certain points) had naturally assumed the likeness of a snake."
Vital Conditions affecting the Colored Population.—Dr. S. S. Herrick, Secretary of the Louisiana State Board of Health, presented facts and tables at the Savannah meeting of the American Public Health Association, showing that, as between the two races, the rate of mortality for all ages is invariably much greater among the colored than among the white, and that the disparity is more marked in the case of children under five years of age. The colored race appears to enjoy an advantage in malarial fevers and cancerous diseases, while it is at a disadvantage in all the other diseases. Mr. Patterson's tables, exhibiting the increase by decades of the colored population in the United States, given in "The Popular Science Monthly" for September, 1881, show that the rate of increase during the decade, including the war, fell off by sixty or seventy per cent. The rate was, however, brought up to near its highest figure in the returns of the last census. The last fact is held by Dr. Herrick to correct the belief that the African race is destined to disappear in the struggle for existence. "Apparently, this race is increasing more rapidly than its white compatriot." The fact, however, which seems to have been overlooked, should be borne in mind, that the mulattoes and quadroons are all reckoned as colored, so that the increase is partly due to the whites. If the rapid increase of the colored race proves anything, it is that there is plenty of room yet for that class of people. This leads to the consideration of what will probably be the future of the colored people when they are crowded upon. "Whatever may be the capacity of the race for development in a state of peace, it is apparent, from the great check on their increase between 1860 and 1870, by the operations of the civil war, that any serious disturbance of their industrial pursuits, like a prolonged foreign war or political convulsions at home, would produce such distress as to disturb profoundly their vital movements. The same event would follow an over-production of the staples grown by their labor, owing to their habitual improvidence. Thus far they have experienced no serious rivalry, and therefore no check to their natural increase. . . . This fact is undoubtedly favorable to the numerical increase of the race, though it is equally clear that it tends at the same time to delay its intellectual improvement by deterring individuals from pursuing other and higher industries. In any event, there is little danger that either race will severely encroach on the ground of the other in our time, and no danger that the colored population of any part of the country will be in the way of the whites, unless they should so far advance intellectually and morally as to win a commanding position by sheer force of merit."
Northern Transcontinental Survey.—A "Northern Transcontinental Survey" has been organized in the interest of the Northern Pacific Railroad and its allied lines, under the direction of Mr. Raphael Pumpelly, the purpose of which is to obtain a satisfactory knowledge of the extensive, hardly explored regions which may be made tributary to those lines and their resources. It has been divided into departments of mineral resources, climate, rivers and irrigation, soils, forests, economic botany, laboratory, and topography, which have severally been put in charge of specialists. A considerable amount of preliminary work was done last year, the most important, perhaps, of which related to the examination of the black coals of the western part of the region under survey and of the brown coal-fields of Dakota. The former coals were found to be good steam-generators, the latter not, except in combination or after special preparation. Particular attention is paid to the forest resources of the country, in which we are glad to see that the economical use of the timber is not wholly left out of sight; and observations are making on the useful grasses of the country. The results of the surveys are to be cartographically represented, in a series of maps delineating severally topographical, hydrographic, climatic, and botanical features.
Langley's Observations on Solar Radiation.—The scientific expedition of Professor S. P. Langley, of the Alleghany Observatory, to the summit of Mount Whitney, in 1881, has led to some important and novel conclusions with reference to the effect of the atmosphere on the action of the sun's rays, and to the temperature of space. Among the principal objects of the expedition were, to determine how much heat the sun sends to the earth (the solar constant), and what part of the surface temperature of the planet is due to the sun's direct radiant heat, and what part to the effect of the earth's atmosphere in storing this heat. Mount Whitney, in Southern California, was chosen, because of the conveniences afforded by its great height and the dryness of its atmosphere, and because two stations could be found upon it within easy signaling distance, and yet having a difference of more than eleven thousand feet in elevation. One of the earlier observations of the expedition was to notice, as former observers had done, "that as we ascended, and the air grew colder, the sun grew hotter, till our faces and hands, browned as they already were by weeks of sunshine below, were burned anew, and far more in the cold than in the desert heat. As we still slowly ascended, and the surface temperature of the soil fell to the freezing-point, the solar radiation became intenser, and many of the party presented an appearance as of severe burns from an actual fire, while near the summit the temperature in a copper vessel, over which were laid two sheets of plain window-glass, rose above the boiling-point, and it was certain that we could boil water by the direct solar rays in such a vessel among the snow-fields." This observation induced the conclusion that if the earth's atmosphere were withdrawn, the temperature of the surface would greatly fall, though under a materially greater radiant heat; and Professor Langley expresses the opinion that the fall would be at least to 50º below zero of Fahrenheit. "We see," says Professor Langley, "if these results be true, that the temperature of a planet may, and not improbably does, depend far less upon its neighborhood to or remoteness from the sun than upon the constitution of its gaseous envelope; and, indeed, it is hardly too much to say that we might approximately indicate the constitution of an atmosphere which would make Mercury a colder planet than the earth, or Neptune as warm and habitable a one." A much greater value than has hitherto been accepted appeared to be given by the observations to the solar constant, amounting to one half more than that determined by Pouillet and by Herschel near the sea-level, and even to more than the recent values assigned by M. Violle. The bolometer observations at the summit and base of Mount Whitney indicate a different distribution of solar energy at the upper station from that which prevails at the lower one. They also indicate, as the author states in a communication to the French Academy of Sciences, that only one quarter of the solar energy which vivifies the world is found in the familiar field of the visible spectrum and the ultra-violet; and that the other three quarters are found in the infra-red. Thus the action of our atmosphere, and, as is inferred from the observations, that of the solar atmosphere, is to absorb the short rays more than the long ones. The real color of the photosphere is blue; and "white light is not the 'sum of all radiations,' nor even of all visually recognizable ones, but a composition of the small groups of special rays, which, starting from this essentially blue sun, by virtue of their large coefficients, and by a kind of survival of the fittest, have struggled through the solar and terrestrial atmospheres to us, while others of short wave-length have failed on the way."
Infectious Consumption.—Dr. Alexander McAldowie has considered the much-debated question whether pulmonary consumption is an infectious disease in the light of his own infirmary and private practice. lie is of the opinion that it is infectious, although it is not so frequently communicated by infection as it would be were the lungs less well protected than they are against the access of germs. He mentions four cases where the wife, previously healthy, and with no family history of tubercular disease, became affected while attending to her phthisical husband, and two cases in which persons suffering from the pneumonic form of the disease appeared to communicate the tubercular form to healthy persons. Phthisis is not often communicated in this manner by ordinary intercourse, because the germs are sifted out in the air-passages by the vibrating action of the cilia situated there, and are removed by expectoration. The germs floating in the air are, moreover, commonly dry, and of feeble infective power. The lungs are liable to infection only when the inhaled germs escape the filtering action of the bronchi and reach the air cells, where they come in contact with a surface highly favorable for their absorption. This happens only under exceptional conditions. The parts of the alveoli most exposed to the attacks of inhaled germs are those near the entrance, at the points where the small bronchial tubes lose their cylindrical character and become covered on all sides with the cells; and pathological observation has proved that these are frequent starting-points in phthisis.
Subterraneous Effects of Atmospheric Pressure.—Hardly sufficient account has been taken of the variations in the pressure of the atmosphere as a force competent to produce important effects within the earth and on its surface. The pressure on a man's body amounts to thirty thousand pounds, and that exerted upon a table ten feet long and five feet wide is equivalent to more than one hundred thousand pounds. In both these cases the pressure varies alike on all sides, and changes are not directly felt; but the cover of an air-tight box, the pressure in the interior of which could not vary, would act very differently, and would respond to the slightest changes. The crust of the earth probably—certainly where cavities exist—is like such a cover. The consideration of this fact may help to explain the connection which many persons think they have found between earthquakes and coal-mine explosions and low stages of the barometer. A part of the weight of the atmosphere being removed, the gases confined within the earth exert a stronger pressure on the crust, or flow out and are inflamed when they reach a light. Mr. Baldwin Latham has found that the streams flowing through the chalk, even in dry seasons, give increased supplies of water when the barometer is falling, and diminished supplies when it is rising.
Mental Shock and Inebriety.—Dr. T. D. Crothers, Superintendent of Walnut Lodge, Hartford, Connecticut, has a paper in the "Quarterly Journal of Inebriety," the object of which is to show how psychical traumatism, or injury from mental agitation or powerful emotion, an agency whose operation is not generally recognized, is often an active cause of inebriety. He marks two distinct periods in all cases of inebriety, the first of which, beginning somewhere in the past, is unknown and not noticeable to ordinary observers, and terminates with the first excessive use of alcohol. The second period starts from this point, is noted by the occasional or continuous excessive use of spirits, is terminated only by recovery or death, and is the period which comes under the observation of friends and relatives, and can be accurately studied. The causes and conditions in the first, or neurotic stage, are often as varied and complex as those which produce insanity, and often, notwithstanding their obscurity, present distinct intimations of inebriety far in advance. "A certain progressive march may be noted, often broken by long obscure halts or precipitous strides, changing into various forms and manifestations of disease. The neurotic stage will be marked, in most cases, by nerve exhaustion, instability of nerve-force, and nutrient perversions. Not unfrequently delusions and hallucinations about foods and drinks are unmistakable symptoms. Often persons who have never used spirits, and become fanatical in their efforts to reform inebriates, are in this stage, and sooner or later glide into the next one." Psychical traumatism may be considered both as a direct cause of inebriety and as an indirect cause, as which it develops conditions that rapidly merge into the disorder. A number of incidents that have come under the author's observation, some of which are extremely striking, arc given as illustrative of its operation from both points of view. In all of them inebriety has immediately or gradually supervened in persons who would have been the last to be suspected of liability to it, after some intense mental shock or surprise or information of disaster. The usual explanation of such cases, says Dr. Crothers, would be that the victims drank from despair and discouragement, "but a general study will show a state of psychical pain and agony for which alcohol alone acts as a sedative. It very commonly appears, in a study of cases of inebriety, that the patient will refer to some event of life, or disease, from which he is confident that he lost some power or force which he has never regained. These incidents do not come out as reasons for his drinking, but as facts pertaining to his vigor or power of endurance." Such cases of loss of power are found in every community, "and of course do not all become inebriates, but, like a large class of eccentrics, are on the border-line, or inner circle, shading into inebriety or insanity. A large number of persons engaged in the late civil war, who suffered hardship and mal-nutrition, became inebriates years after, following the psychical and physical traumatism received at that time. The effects of commercial disasters, of bankruptcies, and panics in Wall Street, can be seen in inebriate or insane asylums. In the asylum at Binghamton, New York, for inebriates, at one time were eighteen cases whose inebriety could be clearly traced to a great money-panic in Wall Street known as 'Black Friday.' Many of these cases were purely from psychical traumatism, others were already in the dark circle close to inebriety, and needed but a slight cause to precipitate them over. Political failures are also fertile fields for the growth of inebriety and the action of psychical influences. Annually a large class, after the close of a campaign, find themselves literally inebriates, and, if they have money, go to water-cures, inebriate asylums, or to the far West, and begin life again. The inebriety is often of the paroxysmal or dipsomaniacal type, with free intervals of sobriety that give renewed energy to the delusive hope that recovery will follow the bidding of the will. A class of moderate or occasional drinkers are always more susceptible to these influences than abstainers"; and it may be stated as a rule that moderate drinkers suffer more frequently from psychical shocks of every form, and are more likely to become inebriates from such causes.
The Poison of Cesspools.—M. Bouveret has reported on a remarkable case of poisoning from a cesspool which took place at Lyons. A workman, twenty-one years old, having fallen into a cesspool, was taken out, after having been in it about five minutes, in a state of convulsions. Inhalations of oxygen were administered for several hours, but the convulsions continued with rise of temperature. Transfusion of blood (defibrinated) was then tried without effect, and death took place about twenty-four hours after the accident. The blood was found, on post-mortem examination, to be black and fluid, the lungs and kidneys were congested, and the bronchial mucous membrane showed a bright hyperæmia, but no coagulation was observed in the pulmonary artery. The chief toxic agent in the contents of cesspools is supposed to be sulphide of ammonium, a poison which acts on the blood in the same manner as carbonic oxide, deoxidizing the red globules and making them unfit to perform their functions. Transfusion of blood has been performed with success in cases of poisoning by carbonic oxide, and its failure in the present case has provoked the suggestion that cesspools may contain gaseous poisons far more complex and more virulent than sulphide of ammonium, the action of which is more profound and complicated.
Ancient Maya Records.—Dr. Daniel G. Brinton, of Philadelphia, has recently come into possession of a number of fac-simile copies of the Books of Chilan Balam, or the local records of the Mayas of Yucatan, and has published an interesting account of their character and contents. The name, "Book of Chilan Balam," was applied to all the works of this character, to whatever village they might belong, and the different ones were distinguished by adding the name of the village. Only a few of the original volumes remain, most of them having been destroyed by the priests as heretical and mischievous; but a few were afterward compiled over again by natives from their own knowledge and recollections. Parts or descriptions of sixteen of these works remain, not one of which has ever been printed, or even entirely translated into any European tongue. Their contents consist chiefly of astrological and prophetic matters, ancient chronology and history, medical recipes and directions, and, in the later ones, later history and Christian teachings. One of the most valuable features in these records lies in the hints they furnish of the hieroglyphic system of the Mayas, concerning which our only information has hitherto been in the essay of Bishop Landa. Some features of Bishop Landa's notes on this subject have been condemned by Dr. Valentini, as we have already mentioned, as "fabrications," but Dr. Brinton pronounces Dr. Valentini's attack "an amount of skepticism which exceeds both justice and probability," and he believes that the result of a comparison with the hieroglyphics of the books of Chilan Balam and of the Codex Troano will refute the doubts and slurs that have been cast on the bishop's work, and "vindicate for it a very high degree of accuracy."
Lessons on the Danger of Narcotics.—The deceased poet, Dante Gabriel Rossetti, was a victim of chloral, which he took for sleeplessness, with the inevitable result. About 1868, his friend Mr. Watts says, in the "Athenæum," he was attacked with insomnia, one of the most distressing effects of which as manifested in him was "a nervous shrinking from personal contact with any save a few intimate friends. This peculiar kind of nervousness may be aggravated by the use of sleeping draughts, and in his case was thus aggravated. . . . No man ever lived who was so generous as he in sympathizing with other men's work, save only when the cruel fumes of chloral turned him against everything." Another conspicuous warning against the use of narcotics is given in the case of the death of Dr. Thomas Atkinson Elias, a physician of Southport, England, under circumstances which led the coroner's jury to believe that it was caused by an overdose of morphia. It was shown at the inquest that he was occasionally troubled with sleeplessness and frequently took for it morphia, chloral, nepenthe, or bromide of potassium. It is lamentable, says the "Lancet," to see medical men drift into such uses of drugs, which engender the very evils for which they arc taken, and are so apt to issue in results quite uncontemplated. "Such evils are to be cured, and meantime borne with patience, not met by dangerous medicines in random doses."
Mechanical and Vital Education.—"Some dangers of education" are treated with much intelligence in a thoughtful essay in the "Saturday Review." One of the dangers relates to the difference between what may be called mechanical and vital education. By mechanical education is meant "the imbuing the mind with those elements which can be taught by pure rule; in which no demand is made on the child or youth beyond attention and industry; into which the clement of choice on his part does not enter. Such elements there are in every subject." Among them are the teaching of the alphabet, of the pronunciation of written words or syllables, of spelling, of writing, of the multiplication-table, of rules for the addition or subtraction of fractions, of many other arithmetical processes, and, in the higher subjects, the inculcation of the Greek and Latin grammar and vocabulary, of the propositions of Euclid, of historical dates and facts, and of many elements in the most difficult branches of learning, the processes of which are mechanical and nothing more. "But in all sound education these mechanical rules are never treated as an end in themselves, nor again as a mere stepping-stone to other mechanical rules of a more difficult kind. They are, each and all of them, keys to unlock the several successive chambers of the world in which we live; and, whether the treasures stored up in those chambers are of a material or spiritual kind, . . . the unfolding of these several treasures is not in any way a mechanical, it is a vital process. And here a totally new element comes in on the part of the student. It is no longer with him a matter of attention only; he will begin to exercise choice. It is found by experience that boys and girls are not incapable of taking interest in the world in which they live; but no prescribed plan for creating such an interest in them is possible. Thousands of interesting topics may be unfolded before the eyes of a boy, and he will have none of them: at last something occurs which touches him; curiosity or sympathy is awakened; and from that moment he takes an initiative, his vital education is on the move. And from that moment the mechanical inculcation of rules ought to be somewhat relaxed; not that it may not still be necessary sometimes, but it ought not to be suffered to interfere with the more important element the spontaneous pursuit of knowledge, the spontaneous feeling of sympathy with men. Now, here is the delicate, the critical point in education, the point at which the teacher or the educational authority has such serious difficulties to contend with in making a decision. . . . There is a proper medium in the enforcement of the mechanical part of education: if it is enforced too little, there is the mischief attendant upon idleness on the child's part, besides the loss of the use of a valuable instrument; if it is enforced too much, vital energies will be quenched, and the whole result will be dry and formal." The tendency in the primary schools, and of all formal competition in the higher schools and universities, is to produce mechanical rather than vital excellence.