Popular Science Monthly/Volume 46/February 1895/Popular Miscellany
A Discussion on Variation.—One of the most interesting sectional meetings of the British Association was one at which a series of papers was read dealing with questions connected with evolution and Darwinism, such as the real nature and cause of variation; the inheritance of acquired characters; the adequacy of natural selection to affect variation sufficiently to explain the great range of animal and plant structure. The first paper was by Prof. D'Arcy Thompson, on Some Difficulties of Darwinism, which was an attempt to deal with the third of these questions. Prof. Thompson suggested that the mechanical and mathematical principles of growth itself may have affected the form of animal life. He instanced the spiral shells of the nautilus and the conical eggs of the guillemot as probably deriving their shape from this principle. The second paper, by Prof. Riley, of Washington, dealt with the very interesting habits of the social insects—ants, bees, wasps, and termites—and showed how all the fresh knowledge accumulated since Darwin's time only corroborated his views, to the effect that in this case the "struggle for existence" of the colony as a whole must be substituted for that of the individual. An interesting point was made by Prof. Haycraft, to the effect that the true function of sex was to keep down variation—that by the combination of two individuals to form a new individual, a mean between the two was always obtained, and that in this way the race was kept constant; whereas, if the new individual could be produced from only a single parent, the limits of variation would be unduly extended. The other papers were by Mr. F. A. Dixey, on Some Fresh Points with Regard to Mimicry in Butterflies; and by Prof. Osborn, of New York, on Certain Variations met with in the Dentition of Fossil Mammals. Prof. Osborn showed how two teeth might come eventually to resemble one another closely, although the stages through which they passed had been widely different. The discussion which followed these five papers was of an animated character, and was participated in by a considerable number of members. Prof. Ray Lankester complained that most of the difficulties suggested had been long ago dealt with by Darwin himself, whose works were insufficiently studied by the younger generations of biologists. The discussion was finally summed up in a most lucid speech by Sir Edward Fry, who complained of the absence of clear issues, and of the consequent difficulty of forming a judgment on most of the points brought forward.
Cambodian Arithmetic.—The Cambodians have a quintesimal system of enumeration, yet they use nine digits and a cipher, and are able to count in practice about as if their system was decimal. Their methods of adding and subtracting are curious. Suppose one wishes to add the numbers 247,372, 53,723, 975,642, 278,383, the sum of which is 1,555,120. The Cambodian writes the first two numbers one above the other, draws a vertical line to the right of them, and writes the sum, 301,095, to the right of the line. Under this number he places the third number of the series (975,642), and adds that in just as he did the first two; and so on till the process is completed. The process is longer than ours, but gives more opportunity for deliberation and the detection of errors. Where whole numbers and fractions are both involved, two series of additions are gone through. In subtraction, they write the lesser number over the larger, and begin at the left; thus, to subtract 657,869 from 786,422, they write
|786,422||and proceed, 6|
The Utilitarian Side of Botany.—Botanists, said Prof. I. B. Balfour, in his British Association address, do not seem to have realized, except in the case of medicine, that modern botany has an outlet. Chemists and physicists seek practical aims. Zoologists help the fishing industry. But where is the practical outcome of modern botany? The work of Marshall Ward is full of purpose to many large industries, and that of Oliver has bearings on horticulture; but the trend of botanical work in England has not been utilitarian. It was, however, its utilitarian side that gave the first impetus to the scientific study of botany. The plant world, as the source of products of economic value and drugs, attracted attention, and out of this grew by natural development the systematic study of plants. The point of view was that botany was an essential branch of medical study. A practical outcome was the establishment of botanic gardens, now in many instances appendages of teaching establishments, or mere pleasure grounds. But the gardens at Kew still maintain the old tradition of botanic gardens as a center through which botany renders scientific service to national progress. Under the Darwinian influence the biological features of the plant world replaced technical diagnosis and description as the aim of teachers and workers. Pharmacy is removed from the functions of the physician; but botanical study on the lines of modern teaching is part of the university training essential to medical students. There is still danger of modern teaching being strangled by its terminology, of narrowing the field of vision and mistaking the name for the thing, of elaborating the minute details of a part at the expense of its relation to the whole organism. This mechanical attitude is a consequence of specialization. But it must be counteracted if botany is to be aught else than a mechanical study. Modern botany has not yet found its full application. It has not rendered the service due to the state. In horticulture and agriculture it should find a sphere of application by which it may contribute to the national well-being. Botanists must be the apostles of forestry; and forestry in turn will react upon their treatment of botany. Botany can not thrive in a purely introspective atmosphere; it can live only by keeping in touch with the national life.
The Uses of Illuminating Gas.—Many are the advantages of gas for household purposes, says William Paul Gerhardt, and its disadvantages are comparatively few, and for this reason it is probably more used in houses at the present day than any other form of artificial illumination. Gaslight is relatively cheap, although kerosene oil, per se, is probably cheaper. It is convenient, and saves domestic labor by being always ready for lighting. It is superior in point of cleanliness to oil lamps and candles. It is brilliant, easily controlled, and not difficult to manage by persons of ordinary intelligence. It is much safer than candles or lamps in which colza oil or kerosene is burned. Gaslight, finally, creates, in proportion to the light developed, less disagreeable heat and is less unhealthful when proper ventilation of rooms is provided than candles or oil lamps. Among other purposes to which gas has in recent years been applied, Mr. Gerhardt mentions its use in warming rooms, heating sadirons, and heating water; in roasting, baking, steaming, frying, boiling, and broiling. It is adopted as fuel to drive small domestic motors, for various industrial purposes; and it is employed for artificial ventilation conducted by means of gas jets burning in exhaust flues, or by the use of sun-burners. Much has been said about the injurious influence of gaslight upon health; of the vitiation of the atmosphere of rooms; and of the destructive effects of gas, when imperfectly consumed, upon the furniture and decorations of a room, and the smoking up of ceilings and walls. But notwithstanding the rapid development of electric lighting, and notwithstanding the recent return in dwellings to the use of oil lamps, and of extensive and costly paraffin and wax candles, the use of gas in dwelling houses, offices, and stores is undoubtedly so convenient and comparatively safe that for many years to come it will constitute the chief means of artificial illumination.
Are Civilized Races Superior?—Proud of his wonderful achievements, civilized man looks down upon the humbler members of mankind, lie has conquered the forces of Nature and compelled them to serve him. He has transformed inhospitable forests into fertile fields. The mountain fastnesses are yielding their treasures to his demands. The fierce animals which were obstructing his progress are being exterminated, while others which are useful to him are made to increase a thousandfold. The waves of the ocean carry him from land to land, and towering mountain ranges set him no bounds. His genius has molded inert matters into powerful machines, which wait a touch of his hand to serve his manifold demands. What wonder, asked Dr. Franz Boaz, in his address before the Anthropological Section of the American Association, that he pities a people who have not succeeded in subduing Nature, who labor to eke an existence out of the products of the wilderness; who hear with trembling the roar of wild animals; who remain restricted by ocean, rivet, or mountains, and who strive to secure the necessaries of life with the help of few and simple instruments? What wonder if civilized man considers himself a being of higher order than primitive man? If it is claimed that the white race represents a higher type than all others? When we analyze this assumption it will soon be found that the superiority of the civilization of the white race is not a sufficient basis for it. As the civilization is higher, we assume that the aptitude for civilization is also higher, and as the aptitude for civilization presumably depends upon the perfection of the mechanism of body and mind, the inference is drawn that the white race represents the highest type of perfection. In this conclusion, which is reached through a comparison of the social status of civilized man and primitive man, the achievement and the aptitude for achievement have been confounded. Furthermore, as the white race is the civilized race, every deviation from the white type is considered a characteristic of the lower type. That these two errors underlie our judgments of races can easily be shown by the fact that, other conditions being equal, a race is always described as the lower the more fundamentally it differs from the white race.
The Problems of Archæological Relics.—The purpose of Mr. Gerard Fowke's Notes on the Archæology of Ohio is to present in a compact form conclusions based upon a careful study of the earthworks and the relics associated with them; embodying a summary of the results reached by all who have been engaged in the investigation. The very wide range of forms and relics—as is shown by the author—the diversity of material, and their unlikeness to almost everything belonging to the present inhabitants, have caused some misapprehension or confusion as to their probable uses. This is especially the case with the great number of objects whose manufacture may be considered the outcome of aesthetic or religious ideas. They are made of nearly all the different kinds of shell, bone, metal, and stone, especially slate and steatite, accessible to their fabricators. Under such names as gorgets, crescents, wands, tubes, banners, stones, amulets, pendants, butterfly gorgets, ear bobs, bracelets, breastplates, beads, buttons, headdresses, labrets, nose rings, charms, and a score of others, they are delineated in many volumes. To ascribe a purpose to any pattern, unless a similar one has been seen in actual service, would be as presumptuous as the attempt by a person entirely ignorant of modern secret societies to explain the meaning of badges, pins, or regalia. No doubt some of them owe their form to a whim or fancy of the maker; others were purely decorative; while many of them were symbolic, or for use in the manifold dances, parades, celebrations, superstitious ceremonies, and other observances so dear to the minds of an uncultured people. The manner of perforation in some indicates that they were for suspension by cord; in others, that they were to be placed upon a staff; still others, unperforated, may have been secured in various ways. Nearly all are made of material that would break if carelessly handled; many are of such size or shape that no particular use for them can be imagined. There is less trouble in regard to the utensils, weapons, or implements for ordinary work, comprising articles necessary in agriculture, hunting, warfare, or domestic affairs. What sort of work the prehistoric people may have done in wood, textile fabrics, feathers, fur, robes, skins, or other perishable material, can never be known; but judging from the few scraps remaining, and from such other specimens as have been preserved, it was probably on a par with that of the present day among tribes but little changed from their condition when first known to the whites. Mi-. Fowke's notes are published, with plates, by Robert Clarke & Co., Cincinnati.
Roger Bacon's Dream of Steam and of Air-Ships.—An essay by Roger Bacon, published in 1618, has been brought to attention by M. de Fonvielle, which contains dim predictions of steam power and the navigation of the air. "Instruments," the author says in this essay, "may be made for navigating without any men pulling the oars, with a single man governing, and going quicker than if they were full of pulling men. . . . Wagons can also be made, that without any horse they should be moved with such a velocity that it should be impossible to measure it. . . . It is possible also to devise instruments for flying, such that a man being in the center if revolving something by which artificial wings are made to beat the air in the fashion of birds. . . . It is also possible to devise instruments which will permit persons to walk on the bottom of the sea. . . . All these things have been done in old times and in our times, except the instrument for flying, which I have not seen, and I have not known any man who saw it done."
The Test of Exactness.—Admitting that the prevailing opinion that great advances have recently been made in astronomy is correct so far as the fields of spectrum analysis and the measurement of minute quantities of radiant heat are concerned. Dr. William Harkness showed in his vice-presidential address at the American Association that the solution of the vast majority of astronomical problems depends upon the exact measurement of angles, and in that little or no progress has been made. Bradley, with his zenith sector a hundred and fifty years ago, and Bessel and Struve, with their circles and transit instruments seventy years ago, made observations not sensibly inferior to those of the present day, and indeed it would have been surprising if they had not done so. The essentials for accurately determining star places are a skilled observer, a clock, and a transit circle, the latter consisting of a telescope, a divided circle, and four micrometer microscopes. Surely no one will claim that we have to-day any more skillful observers than were Bessel, Bradley, and Struve, and the only way in which we have improved upon the telescopes made by Dollond one hundred and thirty years ago is by increasing their aperture and relatively diminishing their focal distance. The most famous dividing engine now in existence was made by the elder Repsold seventy-five years ago; but, as the errors of divided circles and their micrometer microscopes are always carefully determined, the accuracy of the measured angles is quite independent of any small improvement in the accuracy of the divisions or of the micrometer screws. Only in the matter of clocks has there been some advance, and even that is not very great. On the whole, the star places of to-day are a little better than those of seventy-five years ago, but even yet there is great room for improvement. One of the commonest applications of these star places is to the determination of latitude, but it is very doubtful if there is any point on the face of the earth whose latitude is known certainly within one tenth of a second. Looking at the question from another point of view, it is notorious that the contact observations of the transits of Venus in 1761 and 1769 were so discordant that from the same observations Encke and E. J. Stone got respectively for the solar parallax 8·59 seconds and 8·91 seconds. In 1870 no one thought it possible that there could be any such difficulty with the contact observations of the then approaching transits of 1874 and 1882, but we have found from sad experience that our vaunted modern instruments gave very little better results for the last pair of transits than our predecessors obtained with much cruder appliances in 1761 and 1769.
Women in the Higher Education.—The facts presented in a special report on women's education, given in the University Convocation Proceedings for 1893, show that women are gaining in every educational field. The secondary schools of the State returned in that year 23,556 girls of academic grade to 18,243 boys; and of 438 honor credentials issued, 298, or more than two thirds, were to girls. The number of women in colleges had risen to 2,923, of whom 2,078 were in the eight specifically women's colleges, besides 880 in subfreshmen classes. The professional and technical schools returned 4,043 women, and the special schools 3,308. The number of girls entering college from regents' schools was eighty-four per cent greater than the year before, and the increase promised to continue in the current year. Of the teachers in the New York common schools 28,869 were women. In the United States there were in 1890, 125,525 men and 238,397 women teachers. Two years later the number of men had decreased 3,974, and the number of women had increased 14,383. Women are more and more employed as teachers in the grammar and higher schools and in colleges and the university; more of the graduates from women's colleges are entering the medical profession; progress is making in the legal education of women; and opportunities are now offered them to take a theological course.
An Old Book of the Weather.—The first of a series of reproductions of old books on meteorology and terrestrial magnetism undertaken by Dr. D. Hellmann, of Berlin, is the Wetterbüchlein, or Little Book of the Weather, of L. Reyman, the oldest German book on meteorology. It was published at Augsburg in 1505, and passed through seventeen editions in thirty-four years. It has also been translated into English. It is essentially an elementary manual for foretelling the weather from the rudimentary data which the science of the time possessed. The barometer and thermometer were not known, and the principal rules found in Reyman's book are drawn from the appearance of the sky and clouds, the optical phenomena of the atmosphere, the direction of the wind, the phases of the moon, and other like signs. Most of them were known to the ancients and the Arabs, from whose writings the author has derived them—expressing them always concisely and intelligibly to the public. The book is much superior in scientific character to the weather-predicting almanacs of our time; for, instead of pretending to foretell the weather a year in advance, as they do, it has simply given the signs by which its course may be foreseen a short time in advance.
Play and Study.—In a paper on Child Study in Summer Schools, President G. Stanley Hall observes that practically we have to act as if there were no such thing as pure thought. Children have no thought without motion. Motion and thought go together, and if you make them sit still they can not think. Their minds will not move unless their bodies move along with them. We weaken thought if we try to eliminate motion. In the child study at the summer school one thousand children's games were selected and studied, then arithmetic games and geography games, and those that gave strength to the shoulders and hips, "and we had everything that was taught in the whole grammar course without any exception and a good deal more. We cut down these games to one hundred and fifty or two hundred, and found that everything could be taught by historic plays and games. Then we began the history of games, and found that education used to be play, and now it has become hard work. A little while ago older people used to play. It was the spontaneous activity. We have composed a programme of all the school studies taught only by plays and games. I won't say that it is yet practicable; I simply say it can be done. It shows that spontaneities have done everything, just as in the world everything we know has originally been spontaneity, either of geniuses or great discoverers or inventors. I do not go so far as some enthusiasts, but we are realizing that everything in Nature is to be found in the child. Nations as well as associations, institutions as well as colleges and schools, religions and everything else, when judged by the highest standard of right and wrong, will be pronounced good or evil exactly in proportion as they have ministered and conformed to the nature and needs of childhood, adolescence, and growth. That civilization, that school, that college, is best that has devised the most efficient methods for this."
A White Bear's Bath.—The bath of the younger bear in the London Zoölogical Gardens is thus described in Mr. C. J. Cornish's recently published Life at the Zoo: "Fresh water is let into the bath two or three times a week, and as soon as the bottom is covered the younger bear rolls in and 'cuts capers,' to use the keeper's phrase. She always prefers to take a 'header,' but not after the orthodox fashion; for when her nose touches the bottom she turns a somersault slowly, and then floats to the surface on her back. Then she climbs out, shakes herself, and gallops round the edge of the bath. In spite of her bulk, this bear is as active as a cat, and can go at speed round the circle without pausing or missing a step. Her next object is to find something to i)lay with in the water. Anything will do; but if nothing else is handy, she usually produces a nasty bit of stale fish, which she seems to keep hidden in some handy place, and dives for it, coming up to the surface with the fish balanced on her nose, or on all four paws. If the water is still running in, she will lie under the spout, and let it run through her jaws. But the most amusing game which the writer has seen was played with a large round stone. After knocking it into the water and jumping in to fish it out, she took it into her mouth and tried to push it into the hole from which the water was still running. This was a difficult matter, for the stone was as large as a tennis ball, and the pipe was not much wider. Several times the stone dropped out, though the bear held it delicately between her lips and tried to push it in with her tongue. At last she sat up and, holding the stone between her fore paws, put it up to the pipe and pushed it in with her nose. This was a great triumph, and she retired and contemplated the result with much satisfaction. Later, being apparently tired of this achievement, she threw water at it with her head, and, failing to wash it down, picked it out with her claws and went on diving for it in the bath."
Nature's Commerce.—Even before the first human commerce Nature, as Prof. O. T. Mason shows in his Technogeography, had her great centers of superabounding material, and took pains to convert this excess into supply against scarcity. Thus, all over the earth bees gather honey from ephemeral plants that man can not eat, and store it away in enduring form to be used in time of need. In certain regions of California the piñon seeds grew so abundantly that the Indians could not gather them; but the squirrels laid them up in vast quantities, fed on them in winter, and were themselves eaten by the savages at a time when meat diet was most necessary. They thus gave the Indians a lesson in economy and storage. As an example of the way in which Nature uses the excess of one locality to supply the dearth of another locality, Prof. Mason cites the case of the wild rice, which covers thousands of acres in some places along the Great Lakes and feeds millions of waterfowl. These same creatures are the source of food for the Eskimos, who never saw a spear of grass or ate a mouthful of vegetable diet. Seeds of plants enter into migration by a natural transportation through rivers and ocean currents, by means of winds and the agency of birds, and set up in their progeny new centers of supply on distant shores. The most marvelous of these commercial enterprises of Nature is that in which she converts apparently inaccessible and unutilizable material into inexhaustible supplies for every industry of man. A wonderful example of this is found in the littoral feeding grounds. There is a bench of land under the sea skirting every shore and reaching under all estuaries. It is not deep. Indeed, it is the connecting link between the land and the profound sea. Upon this plateau the débris of the fertile lands and of the fresh waters is daily poured, and myriads of the lower plants and animals are developed. Here are nourished cod, shad, herring, salmon, oysters, clams, and so on. The fish after attaining maturity actually swim up to men's doors to be captured. Also upon this feeding ground are nourished the sea mammals which have been indispensable to the life and happiness of our northern aborigines. It is true that every useful plant is converted by Nature out of material which men can not use. Long before Texas cattle were bred in one place and driven hundreds of miles to market Nature reared fish and walrus upon her enormous pasture lands under the sea and drove them to market herself.
Effects of Occupation on Eyesight.—The effects of certain occupations on eyesight are manifested, according to Mr. Simeon Snell, who has made a study of the subject, in a variety of ways. Workers in India-rubber factories are troubled by the fumes of bisulphide of carbon, which is used in the vulcanizing process. The vapor of this substance was formerly employed as an irritant of the conjunctiva and a promotive of abundant, and it tends to produce amblyopia. Amblyopia, or dullness of vision, is brought about in the manufacture of explosives by dinitro-benzyl. While the toxic action of tobacco when chewed seems to be established, the assertion that persons working in tobacco factories are subject to disorders of vision has not been confirmed. The prejudicial action of lead is well known, but to the usual experiences in the matter Mr. Snell adds the curious instance of amblyopia produced among the file-cutters of Sheffield by inhalation of the particles of lead that fly off from the lead bed on which the file is laid to be struck. The statements that glass-blowers are subject to cataract from exposure of their eyes to the intense heat and light of the furnaces are not supported by the later observations. Mr. Snell has found that men can look at metal in the furnace with comparative ease, so long as its is not greatly above 2,000º F.; but when it approaches 3,000º F. they have to wear colored glasses. At cast-iron furnaces, where the heat of the metal is between 1,800º and 2,000º, the men take no special precautions; but the heat of molten steel is between 2,700º and 2,800º, while the heat of the gases in the furnaces would be about 200º or 300º more, and the men in attendance have to wear dark-blue glasses to protect their eyes. The heat of the metal in the Bessemer process is greater still, increasing to 3,000º or 3,200º, but the metal does not have to be so long or so carefully watched as in the Siemens furnace. In none of these cases has Mr. Snell been able to associate any deep or superficial eye lesion as the result of exposure to intense light and heat. Exposure to the light employed in electric welding causes sharp conjunctivitis, with great pain and tear-shedding, and, if it be allowed to enter the eye, optic neuritis, with retinitis and a central scotoma in the vision. The effects are due to the chemical rays, and the men are obliged to use screens made of dark ruby, non-actinic glass.
Geological Work of the Atmosphere.—Believing that too little attention has been given by American geologists to the work performed by the atmosphere in erosion, transportation, and sedimentation. Prof. J. A. Udden, of Augustana College, has considered the subject in a brief paper. He begins by assuming that as an agent of erosion air is far less efficient than water—because of its small weight, it being only 1 as heavy as water, and because it exerts no wave motion on the surface of the earth. The erosive action of wind therefore becomes important only in certain localities, under the favoring conditions of a dry climate and a topography of abrupt and broken reliefs. Since the speed of the wind is lowest near the surface of the ground, materials to be transported any considerable distance by the atmosphere must be by some means lifted through and over this zone of low velocity. This condition is furnished by whirlwinds and reliefs which cause eddies or give the wind an upward direction. To be subject to transportation by the atmosphere, rock materials must be finely comminuted; and the author has ascertained by experimeut that the average largest diameter of quartz particles that can be sustained in the air by ordinary strong winds is about one tenth of a millimetre. But the capacity of the air for transporting particles below this size is very great, and is estimated to be per cubic foot at an average velocity of five miles an hour, one thousandth that of water. The whole atmosphere over the Mississippi Valley, if the wind blows ten times as fast as the river runs, may transport one thous.and times as much dust. Atmospheric currents being loaded, for the most part, only to the extent of an insignificant fraction of their capacity, their sediments will be better sorted—the fine material will be more completely separated from the coarse—than deposits from water currents, which are more often loaded to their full capacity. That deposition of dust will take place where wind is caused to slacken its speed is self-evident, and is observed every day in the accumulation of dust on the windward side of a closely built-up street.
Boarding Schools and Infection.—The Agency of Boarding Schools in Disseminating Infectious Diseases was the subject of a paper by Dr. Clement Dukes at the Congress of the British Institute of Public Health. The author charges boarding schools with not having exercised sufficient care in the protection of society against sanitary detriment from influences they might control. The conditions of boarding schools, with their regular vacations and occasional leaves of absences, are such that there is almost a perpetual to-and-fro communication between them and the home. Then, when pupils become ill they are sent home, if practicable; and when general illness breaks out in the school, those who have as yet shown no symptoms of it, or only the beginnings of them, are sent home These pupils, possibly bearing the seeds of infection, travel in the public conveyances in contact with unsuspecting passengers, or to be followed by such, to whom disease may be communicated. The spread of infectious dis. eases by boarding schools is admitted to be, unfortunately, to a certain extent, necessary by virtue of the existing system and the susceptibility of the pupils. Beyond this, such diseases are often disseminated ignorantly and thoughtlessly by the operation of motives in which such result is not contemplated, or wantonly. As remedies for the evil the author suggests bills of health to be given by parents on sending their children to school and by teachers on sending pupils home; and that schools should make adequate provision for the treatment of illness of their pupils and for the retention of all patients till they are absolutely free from infection.
Mistaken Diagnoses.—Common Diseases Mistaken or Mistreated is the subject of an address recently delivered before a medical society by Dr. J. F. Goodhart, of Guy's Hospital. It concerns the diagnosis and treatment in every-day practice of cases which practitioners must see regularly, which are yet frequently mistaken and mistreated. Infantile scurvy, for instance, is a very common complaint, but is often not recognized, and allowed to pass as rickets or rheumatism, or injury, or temper. Another disease which, although very common, varies much in severity and in the mode in which the pain manifests itself, is angina pectoris. It is often mistaken for indigestion, neuralgia, rheumatism, flatulence, etc., and fatal results have often followed from the wrong treatment having been adopted. Other instances of error occur in the confusion of the passage of urates with that of uric acid, in the adoption of a rigid form of dieting to get uric acid out of the system, when it is the individual that should be treated, and his malady, individualized in him, through him; and in the treatment of renal colic and chlorosis. The author emphasizes the fact that many of the methods and aims of medicine are faulty by reason of the ready assumption that their bases are unassailable; that men are constantly driven back upon their own experience, and compelled not to accept it but to question it.
Tests for Old Plumbing.—The tests usually applied in inspecting old plumbing work, as named by William Paul Gebhard, are the peppermint test, the smoke test, and sometimes an air-pressure test. The water test is not practically applicable to plumbing work in actual use, because it necessitates the disconnecting of all fixtures, and even then there is risk in applying it of flooding parts of the house. "The peppermint test is useful in a measure, but unless great care is taken in applying it the results are at times misleading. It is, therefore, in the hands of inexperienced or unscrupulous persons a rather dangerous and somewhat objectionable test. It is not always possible to define by it the exact position of the leak, or to determine exactly what the defect is. In the more positive smoke test, on the other hand, any leakage becomes apparent to the senses of smell and sight; in fact, in nearly all cases, except where leaks are very slight, the issue of smoke will indicate the exact point at which plumbing is unsafe. In order to have continued assurance that the plumbing and the drainage and the gas-piping remain safe, it is advisable to repeat the tests from time to time. The walls of a building settle, the pipe joints may become untight, or the joints may open by expansion when much hot water passes through the waste, or pipes may break, or traps may sag or tip over, rubber gaskets of floor joints may disintegrate and rot, leaving open cracks through which sewer air may pass, or joints made with brass couplings may become loose, and rubber or leather washers may rot; in short, there are numerous points which in a plumbing system may become defective after it is in use for some time. Hence the necessity of periodical re-inspection, which is just as desirable with plumbing work as it is with steam boilers or other machinery."
The Electric Arc.—In a lecture at the Royal Institution on Electrical Illumination Prof. J. A. Fleming exhibited the formation of an arc between carbon rods, and said that it had been experimentally proved that the arc could not be started unless either the rods were first brought into contact or the insulating power of the air between was broken down by an electric spark. An immensely magnified imago of the arc was projected on the screen, so that its interior structure was rendered visible. It was seen, for instance, that the positive carbon rod becomes most intensely hot at the extremity and hollowed out into the form of a crater, from which about eighty per cent of the total light is emitted. The negative carbon does not become so hot. The space between the two, or the true arc, is filled with vapor of carbon. In the central space a brilliant violet axis is seen, violet being the color of incandescent carbon. Outside this is an auraole of carbon vapor of yellow or golden color. With the use of a prism the central axis of the arc gave a spectrum marked by two brilliant violet bands. It was next shown that the rise of electric pressure in the arc takes place chiefly at the surface of the crater, which is in fact the place where the work is done in evaporating the carbon. The light emitted is therefore due chiefly to the incandescence of the carbon in the crater. Hence the light is not given off equally in every direction. It is most intense in that direction in which the largest area of crater can be seen.
Humming Birds as Carriers of Pollen.—The agency of humming birds in transferring pollen from flower to flower is shown in a paper by Joseph L. Hancock to be parallel in importance with that of insects. The common ruby-throated humming bird, though it is not endowed with specialized structures for the specific performance of this office, has in its mouth parts and feathers means for harboring the pollen. The anatomical peculiarities of its head permit access to flowers of a wide range of forms. The bill, by virtue of its flexibility, is capable of probing to the bottom of most of the common forms of flowers; and in the feeding process the flower is often bent over. The various ways in which pollen is carried to this bird were revealed on microscopic examination of some dead specimens. On the lower mandible just in front of the angle of the mouth, overshadowed by the nasal scale when the bill is closed, a faint yellowish line marks the deposit of pollen grains resting, clustered together, in a small groove. Pollen grains work their way free to the summit or vanes of the feathers, and are caught up by the barbs of the feathers along the sides of the chin and lores, where they remain ready to be deposited when a more suitable surface is presented. A second receiver of pollen is the deep median groove under the lower bill, the point of meeting of the rami. Four ways have been observed by the author in which pollen becomes engaged or held by the feathers. In flowers, the pollen of which is carried by the wind, the grains are small, light, and more or less dry and spherical; in flowers in which it is carried by insects they are variously adapted to adhere to the under side of the carrier's body; in those whose pollen is distributed by birds it is carried in so various ways that this circumstance combined with other data indicate the possibility of the humming bird being the most wonderful distributor of pollen known to the animal world.
In an Engineering Laboratory.—The work of an engineering laboratory, observed Prof. A. B. W. Kennedy in his British Association address, is in intention and in essence different from that of the physical laboratory. The aim of the latter is to make its problems as simple as possible, to eliminate all disturbing elements or influences, and to obtain finally a result which possesses the highest degree of absolute accuracy. In most physical investigations the result aimed at is one in which practical absolute accuracy is obtainable, although attainable only if infinite pains be taken to get it. It is the business of the physicist to control and modify his conditions and to use only those which permit of the desired degree of accuracy being reached. In such investigations it sometimes becomes almost immoral to think of one condition as less important than another. Every disturbing condition must be either eliminated or completely allowed for. That method of making the experiment is the best which insures the greatest possible accuracy in every part of the result. The business of the engineer, on the other hand, is to deal with physical problems under conditions which he can only very partially control, and the conditions are a part of his problem. Perhaps the whole matter may best be summed up by saying that in a physical laboratory the conditions of each experiment are under the control of the experimenter and are subservient to the experiment. In an engineering laboratory the conditions form part of the experiment. Whenever the whole matter seems to be mastered from one point of view, it is only to find with a little more experience that from another point of view everything looks different and the whole criticism has to be started afresh. Machines can not be finally criticised—that is to say, they can not be pronounced good or bad simply from results measurable in a laboratory. One wishes to use steam plant, for instance, with which as little coal shall be burned as possible; but clearly it would be worth while to waste a certain amount of coal if a less economical machine would allow a larger saving in the cost of repairs, or it might be worth while to use a machine in which a certain amount of power is obviously lost if by means of such a machine the cost of attendance can be measurably reduced.