Popular Science Monthly/Volume 21/July 1882/Popular Miscellany
American Forestry.—An American Congress of Forestry was held in Cincinnati, beginning April 25th, of which the Hon. George B. Loring, Commissioner of Agriculture of the United States, was chosen President for the year. Ten State and Provincial organizations, one of which embraces the Canadian Provinces, were recognized, and sections were constituted, as follows: A. Uses of Forests; Dr. Franklin B. Hough, President. B. Conservation of Forests; Dr. John A. Warder, President. C. Influences of Forests, Injurious and Beneficial; Professor William Saunders, President. D. Educational Means; Professor N. P. Egleston, President. Professor William Saunders, of London, Ontario, read a paper on "Insects affecting Forest-Trees," in which he considered the various means of preventing and remedying insect depredations. Dr. George Vasey, of Washington, D. C, read a paper on "The Distribution of Conifers in the United States," and was followed by a discussion on resonant trees, in which the American cypress was declared to be far superior for musical instruments to any foreign wood. Mr. Hough gave an account of what had been done by the State of New York in the matter of the Adirondack Park, after which resolutions were adopted approving the policy of establishing the park, and recommending the adoption of similar measures by other States. Mr. Verplanck Colvin presented a paper on "The Decay and Preservation from Decay of Wood," in which the merits of several preservative substances were considered. Professor Lane read a paper on "The Importance of Experimental Stations of Forestry," and the Congress recommended the establishment of such stations, to be under the care of the agricultural colleges, with a central station. In a paper on "The Profits of Durable Trees," Dr. A. Furness, of Danville, Indiana, showed that an investment of $50 for one acre of land and $25 for tree-plants had returned him in sixteen years a clear profit over all expenses and taxes of $1,048. Mr. C. David, of Madison, Indiana, read a few notes "On the Natural Growth of Forest-Trees" which had given him in about thirty years^ upon an originally bare prairie, a wood of timber-trees from twelve to sixteen inches in diameter. Dr. F. B. Hough stated that a journal devoted to the interests of forestry would be begun soon, to be edited by himself, and published by Robert Clarke & Co., of Cincinnati. Committees were appointed to report on the importance of experimental forest stations; to suggest a plan for the prevention of the destruction of forests by fire and cattle; to report on the importance and necessity of State commissions of forestry; on forest-culture, and on forestry schools. The next meeting was appointed to be held at Montreal, Canada, August 21st and 22d of this year, two days before the annual meeting of the American Association for the Advancement of Science, when reports from these committees are expected. One of the days of the convention was styled "Arbor Day," and was devoted to the planting of trees in the public squares and Lincoln Park. A large number of the trees were named in honor of public men and distinguished citizens, etc. This, though not of particular practical bearing, tends to awaken interest in a cause that needs such awakening sadly enough.
Sound-Shadows in Water.—Professor John Le Conte has described in the "American Journal of Science" a course of investigations, which he has made with the assistance of his son, on sound-shadows in water. It is probably within the experience of all that more or less perfect sound-shadows are thrown by hills, buildings, piers, and other obstacles, to the transmission of aerial vibrations. Nevertheless, the boundaries of such shadows are so imperfectly denned that they can hardly be compared, except in a general way, with the shadows of light. Many ordinary obstacles are elastic and give passage to a part of the sound, as translucent bodies let a part of the light through; and waves are liable to a diffractive divergence, which proceeds from the secondary waves that originate at the boundaries of the obstacle and are propagated within the geometrical shadow. Lord Rayleigh refers the difference in effect in the case of sound as compared with light to the difference in the proportion of the wave-lengths of the two phenomena to the size of the obstacle. An ordinary obstacle bears an immense ratio to the length of a wave of light, but does not bear a very great ratio to the length of a sound-wave. Hence it follows, from the mathematical theory of undulations, that the waves of sound bend around obstacles, and produce more or less effect within the geometrical shadow, while light-shadows have definite boundaries, and are more sharply defined. These views appear to be confirmed by experiment; for the shadows cast by acute sounds are more distinct than those produced by grave sounds. It is also a significant fact that sound-shadows seem to be more perfect or more sharply defined in water than in air. David Colladon found this to be the case in 1826. Professor Le Conte's son, under his direction, made some experiments in this matter during the removal of Rincon Rock at San Francisco, by blasting with dynamite, in 1874. The shock produced in the water—which was felt at the distance of three hundred feet as a short concussion or click—was followed by a second shock in the air, that was heard. When the observer stood upon the top of a wooden pile, the concussion seemed to come up from the water along the cylinder of wood. A soda-water bottle was let down near a pile about forty feet from the explosive cartridge. Whenever it was left within the geometrical shadow of the pile from the cartridge, it was not hurt by the explosion; whenever it was placed outside of the shadow it was shivered to atoms, and this whether it was filled with water or with air. In other experiments stout glass tubes firmly adjusted to a frame-work supporting them, were let down horizontally so as to He across the piles. In every case the shock of the explosion shivered the parts of the tube that projected on either side of the posts, and left the part within the shadow uninjured. The boundaries between the broken and the protected parts of the glass were sharply defined. The same effects were produced when the tubes were put twelve feet beyond the pile. Professor Le Conte explains these phenomena by endeavoring to show that the sound-shadows are more distinct in water than in air because the sound waves are shorter in that medium. The character of the explosion also probably has much to do with the nature of the effect: the sharp, sudden detonation of nitro-glycerine is calculated to generate shorter waves than a more deliberate explosion. This view is confirmed by the fact that, when an extremely disastrous explosion of nitro-glycerine took place in San Francisco in 1880, a violent concussion was felt in the University buildings, three miles away, while no aërial shock was felt at Professor Joseph Le Conte's house, eight hundred and ninety feet farther off, but within the geometrical shadow of one of the buildings. The sound-wave coming by the air was completely cut off by the acoustical shadow cast by the intervening: structure. This would not have been the result in the case of ordinary sounds.
The Salmon-Disease.—Professor Huxley recently read a paper before the Royal Society on the disease which prevails occasionally among the salmon in North America and Siberia, in which he reviewed the results of the commission that was appointed in 1878, when the disease raged in the Solway district, to investigate its nature. The evidence taken before the commissioners leaves no doubt that the malady is to be assigned to the diseases caused by parasitic organisms, and that it is a contagious and infectious disease of the same order as ringworm, the muscardine among silk-worms, and the potato-disease, and is the work of a minute fungus. In fact, the Saprolegnia which causes it is an organism closely allied to the Peronospora, which is the cause of the potato-disease. One distinction may be marked between them, that the Peronospora are parasites depending altogether upon living plants for their support, while the Saprolegnia are essentially saprophytes, that is, they ordinarily derive their nourishment from dead animal and vegetable matters, and are only occasionally parasites upon living organisms. The zoöspores of these plants, diffused through the water, germinate and produce a mycelium similar to that from which they started as soon as they reach the healthy skin of a salmon. Professor Huxley experimented in inoculating the bodies of dead house-flies from the diseased salmon-skin, and in a few hours saw the bodies completely taken possession of by the white filaments of the fungus; it was proved to him that the pathogenic Saprolegnia of the living salmon may become an ordinary saprogenic Saprolegnia, and, per contra, that the latter may give rise to the former. Hence the cause of salmon-disease may exist in all waters in which dead insects infested with the Saprolegnia are met with. The Saprolegnia do not appear to be found on decaying bodies in salt-water. We must, therefore, "look for the origin of the disease to the Saprolegnia which infest dead organic bodies in fresh waters. Neither pollution, drought, nor over-stocking, will produce the disease if Saprolegnia are absent," although they may favor the conditions on which its spread depends. Professor Huxley also concludes that the chances of infection for a healthy fish entering a river are prodigiously increased by the existence of diseased fish in that river, insomuch as the bulk of Saprolegnia on a few diseased fish vastly exceeds that which would exist without them. Hence, "the careful extirpation of every diseased individual is the treatment theoretically indicated; though, in practice, it may not be worth while to adopt that treatment."
Catalogue of Scientific Periodicals.—Dr. H. C. Bolton, of Trinity College, is preparing for the press his long-delayed "Catalogue of Scientific Periodicals," which will appear in the octavo series of the Smithsonian Institution. The catalogue is intended to embrace independent journals of pure and applied science, published in all countries, from 1665 to 1880; so far as possible, minute details will be given concerning changes of title, sequence of series, editorship, and date of publication. The arrangement of titles will be strictly alphabetical, but periodicals having different names at different periods will be grouped together under the heading of the first or earliest title of the series, cross-references being made in all cases. A peculiar feature of the catalogue is presented in synoptical tables containing the dates of publication of each volume of the periodicals named, exhibited by a method slightly modified from the plan originated by Professor James D. Dana, and is described in his "System of Mineralogy" (page 34, foot-note). Only a limited number of the periodicals can be entered in the synoptical tables, as preference is given to those which were published during a long series of years, or were issued very irregularly. The publication of the data contained in these tables was at one time abandoned on account of supposed typographical difficulties, but these have been overcome. The catalogue does not embrace transactions of learned societies, these being found in the admirable "Catalogue of Scientific Serials," by Mr. S. H. Scudder; but it does embrace every branch of applied science, including engineering, architecture, chemical technology, geography, ethnology, agriculture, horticulture, telegraphy, meteorology, etc. More than twenty languages are represented in the work, which it is hoped will be completed before the close of the year.
Sioux Superstitions.—Mr. H. C. Yarrow has communicated to the Anthropological Society of Washington, D. C, some observations by Mr. William E. Everett, a Government scout at Fort Custer, on some superstitions of the live Indians. The Sioux believe that when they die they go directly to the "Great Spirit's Big Village," having to cross a long divide, and perhaps fight the spirits of their dead enemies on the way; for this reason they want their best horses killed with them, and their arms put by their side. Reaching their paradise, they are received by their friends and relatives and escorted to a fine lodge, where they meet their wives and children that have gone before; all their war-horses that have been killed in battle reappear before them; if they have been maimed in war, their missing members immediately return to them; if they have mutilated themselves greatly for some friend or relative, that person comes to them and embraces them, and makes them large presents; and they find themselves encamped amid most delightful surroundings. Their idea of sickness is that a bad spirit of one of their enemies has entered the sick person, and must be driven out by noise; and a great uproar is made, while the invalid is made to inhale the smoke of sweet grasses and herbs to assist in the exorcism. Bad spirits are believed to be sometimes sent back to earth in the shape of some animal, and Indians often fancy that they can talk to their friends under such forms. Mr. Everett once saw Sitting Bull making motions with his hands, and talking to a large wolf, which apparently understood what he said, "for whenever he would make the sign for 'Do you understand?' the wolf would throw up his head and howl." The chief told Mr. Everett that he was making medicine to find where the main herd of buffalo were, and whether it would rain or snow before the hunters got back; and he said the wolf was the spirit of a great hunter, and always gave him warning whenever there was any danger close at hand, and told him where the buffalo were to be found. He also repeated some predictions the wolf had made to him, which seem to have been afterward exactly fulfilled. A remarkable superstition prevails with relation to the white-tailed deer, and is so strong that an Indian can seldom be induced to shoot one of those animals. They believe that the deer embodies the spirit of a woman, who, if it is killed, will appear before them and kill them, or make their life a torture. Mr. Everett is acquainted with several stories of Indians who started out, in spite of the superstition, to hunt the white-tailed deer and did not return, but who were afterward found, by their friends going out to search for them, lying by the side of a dead deer strangled, with the marks of a woman's hand on their throat, and a woman's feet on the ground. One grim story of this character, which he repeats with its particulars, relates to six young men who went out together and shot six deer, and were found strangled, with marks of fingers on their throats, and horrified looks, as if they had seen something awful. A curse was pronounced upon the spot where the tragedy happened, by the oldest man of the tribe, which was said by the Indians to have been fulfilled to the letter.
What are Sun-Spots?—Opinions respecting the nature of the sun-spots vary widely. Secchi thought they were clefts filled with metallic vapors; Weber and Kirchhoff, that they were clouds of smoke; Reis, that they were clouds of vaporized oxyhydrate of iron; and Faye, Zöllner, Gautier, Spiller, and Spörer, that they were a dross formed by a cooling of the sun's fiery matter. None of these theories is fully satisfactory. The hypothesis of clouds of smoke hardly agrees with the immensely high temperature we have to ascribe to every part of the sun's surface, and the supposition of a dross would require a greater degree of cooling than could possibly take place there. Herr Edmund von Ludwighausen Wolff has advanced the theory in "Kosmos" that the spots, instead of being cooler, represent parts of the sun that are vastly hotter than the rest of its body; that is, that they are regions in which all the heat-movements have reached the intensity of the ultra-violet and invisible rays; consequently, they appear dark. Herr Wolff remarks that Secchi's observation that the spots gave out not less but more heat than the rest of the sun's surface, and Fraunhofer's that the forces that produce the spectrum-lines appear to be more active in the spots, and the fact that flashes of light are frequently seen to spring up from the midst of them, are contradictory to all previously received theories, but agree fully with that which he proposes, and are clearly explainable by it.
The Laws of Rain-fall.—Professor E. Loomis has prepared, in aid of his studies of the laws affecting the amount of rain-fall at different places, a graduated table of the average annual rain-fall at more than seven hundred points. Of two hundred and four stations at which the mean exceeds seventy-five inches (rising from this amount to 492·45 inches at Cherapunji, Assam), some are elevated more than two thousand feet above the sea, and nearly all are within one or two hundred miles of elevated mountains. Rain chiefly occurs when the wind from the ocean is blowing toward the mountains, and the extraordinary rain-fall at most of them is probably due to the influence of the mountains, by which the wind is deflected upward to such height that a considerable part of the contained vapor is condensed by the cold of elevation. The cases in which the rain-fall is excessively deficient are, on the other hand, those of places in which nothing exists that may cause an upward current of air. Another cause of deficient rain-fall, frequently exemplified, is the descent of a current of air which has been forced up to a great height and suffered condensation of its vapor, after it has crossed the mountain, by the influence of which it has been raised, when its temperature rises and it becomes dry. Such effects are produced by the Rocky Mountains on the plains east of them and by the Himalayas on the Desert of Gobi; and the operation of these two causes will assist in explaining most of the rainless districts of the globe. Other influences modifying the amount of rain-fall are, the meeting of the northeast and southeast trade-winds, which results in a great rain-belt surrounding the globe; the irregular barometric depressions of the middle latitudes, indicating frequent storms; proximity to the ocean, especially when the prevalent wind comes from the sea; and the projection of capes and headlands into the ocean, which contribute to frequent rains. Uniformity in the direction of the winds throughout the year, such as prevails in the trade-wind regions, obstruction of the free movement of surface-winds by mountains, remoteness from the ocean measured in the direction from which the prevalent wind proceeds, and high latitude, tend to produce a dry climate. These principles do not seem to be fully borne out by the phenomena of rain on either side of the Alleghany Mountains, but we have not yet systematic enough or careful enough observations to enable us to determine what is their real influence. Mount Washington, in New Hampshire, exerts a marked influence. The mean annual precipitation there is seventy-seven inches, while in the surrounding districts it is only forty inches.
Improved Sanitary Condition of London.—The report of the English Registrar-General for 1880 completes the fourth decade of reports since the weekly return of that officer was first published. It shows that the death-rate in London for the year (taking the population of the metropolis as given by the last census) was not more than 21·5 per thousand inhabitants, than which a lower death-rate has been returned in only three of the last forty years. The decade closing with 1880 was one of lower mortality in London than any of the three decennial periods for which trustworthy statistics are available, the rate having been 22·4 for 1880, and having ranged from 23·7 to 24·9 in the three decades from 1841 to 1870, and averaged 23·4 during the whole period. The health of London, which was practically stationary during the thirty years ending with 1870, showed a marked improvement during the following ten years; and it may be estimated that at least 70,000 persons were living within registration in London at the end of the ten years who would have died had the mean death-rate of the preceding thirty years been maintained. Dividing the ten years into two periods of five years, the death-rate appears to have been considerably lower in the later than in the earlier period. These facts afford strong evidence of the efficacy of the sanitary efforts of late years in the face of the increasing density of the population, which has, of course, worked against them. This ascription of improvement to the effect of sanitary measures is justified by the fact, that the most marked decrease in mortality is in that from zymotic diseases. The average annual death-rate from fever fell from 0·92 per 1,000 during the first three decades of the forty years to ·37 per 1,000 in 1871-'80. The rate of infant mortality has not, however, diminished to a corresponding proportion with the mortality from other classes of diseases.
The Aquarides, or July Meteors.—M. Cruls has communicated a notice of the meteors which the earth meets between the 25th and 30th of July, called Aquarides, because they appear to radiate from a point near δ Aquarii, of which regular observations have only recently been made under favorable conditions. The possibility of the earth meeting at a point in its orbit one or more currents of asteroids is very admissible. Each of these currents might be defined by its proceeding from distinct centers of emanation which may be determined by the crossing of the trajectories; but, to give a character of certainty to the existence of these centers, the determination should rest upon the definition of an adequate number of trajectories. If the existence of a considerable number of radiant points should be verified by continued observations, the phenomena would lose the character which a few trains isolated and distributed after a certain manner in space would present, and would assume that of an intricacy of asteroidal currents, compelling the admission that the infinite multitude of corpuscles occupies an immense zone analogous to the zodiacal light, and possibly having a certain connection with it. M. Cruls believes without doubt that the zodiacal light extends beyond the orbit of the earth, at least in certain directions; while he was observing the meteors in July, he saw the zodiacal light at one o'clock in the morning distinctly projected upon the zenith, and extending toward the eastern horizon; the earth was at that moment within its limits. Three astronomers and three pupils participated in watching the meteors at Rio, from the 25th to the 30th of July. They counted 2,710 meteors, and estimated that five per cent of the whole number escaped observation. It was manifest to all the observers that ninety per cent of all the paths of the meteors intersected each other in the neighborhood of Fomalhaut. The horary means increased fast from the hours of evening till those of morning, and exhibited a remarkable incandescence near sunrise. This seems to indicate that the swarms of meteors move in an opposite direction to the earth; for in that case, the movement of the earth at sunrise being directed toward that point in the ecliptic which is on the meridian, the meteors would then enter the atmosphere under more favorable conditions of speed than at any other hour of the night.
Piseco Lake-Trout and T Lake Falls.—Piseco Lake, in the Adirondacks, formerly the fishing-grounds of the once famous Piseco Club, was noted in the earlier days of its frequentation for the wonderful catches of trout it afforded. According to the statement of the Rev. Henry L. Ziegenfuss, in "Forest and Stream," an average of less than six men fishing from the club-house at Walton Lodge, for an average of less than nine days annually, succeeded in capturing in nine years—1842 to 1850—more than three tons of trout. The largest trout ever taken from the lake which was called for distinction the "Emperor"—was caught on the 24th of June, 1842, and weighed twenty-six pounds and eight ounces. Another fish weighed twenty pounds and a quarter, and measured three feet, less half an inch, in length, and two feet, less half an inch, in circumference. In June, 1847, the president of the club killed a red-fleshed lake-trout that weighed twenty-four pounds, the largest that was ever taken there by trolling. Within eight miles of Lake Piseco is T Lake, whose waters flow down the mountains toward West Canada Creek over a fall of nearly seven hundred feet, into the pool called "Snowstorm's Delight." In midsummer but little water comes down from the lake, but in spring and fall immense volumes thunder over the height with a roar that is heard at Piseco. Many extravagant statements are current respecting the height of the falls, but the matter has been partly settled by the measurements of Colonel J. T. Watson, of Clinton, New York, made in 1876. The swift rapids at the top of the falls are one hundred feet in length; the sharp pitch three hundred and ninety feet, and the almost perpendicular fall below two hundred feet, giving a total of six hundred and ninety feet. The falls are thirty feet wide at the top and three hundred feet at the bottom.
The Teleradiophone.—M. Mercadier, the French electrician, has ingeniously adapted the photophone to telegraphy. When, in working with the photophone, the ray of light striking upon the selenium receiver is eclipsed many times in a second, a continuous hum is produced, and this may be broken up into signals by varying the intervals between the intermissions, so that a kind of Morse alphabet can be played upon the instrument. An arrangement for producing signals of this kind is attached to the transmitting instrument, when the signals are sent along the line to a telephone at the other end. No gain over the ordinary telegraph is realized by such an arrangement, but, by multiplying the number of transmitters at one end and the number of telephones at the other end, it can be made to admit of several different messages being sent along the same wire at a time, and of sending messages at once from opposite ends of the wire without confusion. In order to give the multiple messages effect, it is only necessary to rotate the eclipsing wheels, which act upon the several selenium receivers at different speeds, so as to produce notes of different pitch in the receiving telephones, and to fit each resonator so as to enhance a particular note. Then, although the complex current flows through all the telephones in turn, each telephone will only render to the ear of the clerk the particular note for which he listens, and the makes and breaks of that note will be the message.
Origin of the Astronomical Symbols.— Every one who consults an almanac is acquainted with the curious figures that appear in its pages as symbols for the planets and for celestial phenomena—the only real hieroglyphics which survive in current use to our day—but few, probably, have examined into their origin. Modern text-books on astronomy do not condescend to discuss such matters, but the books of the two former centuries gave full explanations on these as well as on some other points, which the school-room science of to-day is too dignified to consider. Such books were Lalande's "Astronomy," in French; Long's, in English; and Riccioli's "Almagestum Novum," in Latin. Lalande shows that , the symbol of Mercury, is derived from the caduceus, the serpent-wreathed mace of the Greek and Roman divinity; is a hand mirror, the most appropriate symbol of Venus, the goddess of beauty; , a lance, nearly covered by a buckler, which it most became the god of war, whose planet, Mars, it represented, to carry; , a capital Greek zeta, the first letter of the name of Zeus, or Jupiter, re-enforced by an intersecting stroke; , the sickle of old Father Time, Chronos, or Saturn; and and , figures of the disk of the sun and of the new moon. Huet gives the same explanation in his notes on Manilius, and Long gives a series of artistically designed pictures of the objects themselves, from which the figures are derived. The symbols for the sun and moon are very ancient. They occur on the Egyptian monuments, and are mentioned by Clement of Alexandria in the second century. The others are of comparatively modern date, and are not so old even as the Arabian manuscripts. They were invented by the astrologers of the middle ages, and arc said by Humboldt to be not older than of the tenth century. The sign for the earth, , a globe surmounted by a cross, indicating its Christian origin, may be traced to about the sixth century. Of the recently discovered planets, the sign for Uranus, , is a modification of the initial H of Herschel; and that for Neptune, , is derived from the trident of the sea-god. The attempt to give similar symbols to the smaller planets was abandoned after they began to be too numerous to be distinguished in this manner.
Obesity and its Treatment.—According to the observations published by M. de Saint-Germain, in the "Union Médicale," the great danger to be feared from obesity lies in the direction of lesions of the heart. Considerable differences exist relative to the influences of sex on the liability to the affliction, but M. de Saint-Germain believes that women are the more liable to it, and that in proportion as they are addicted to alcoholism, prostitution, or inactivity. It may be developed at any age, even as early as two years; M. Hillairet recently exhibited at the Academy of Medicine a little girl six years old who was wonderfully fat. Among the causes of obesity are mentioned excess of food and of alcoholic drinks, too much sleep, and occasionally marriage. Widowhood, which makes men fat, appears to have the contrary effect on women. M. de Saint-Germain illustrates his method of treatment by citing the example of one of his best friends who was most probably himself. Having grown to the weight of two hundred and thirty pounds, he tried to train himself down by the regulation method of treatment, and in six weeks lost twenty-nine pounds and all his strength. He then stopped, recovered his weight and his health, and suffered no particular change for eight years. Then he took to horseback riding, gymnastics, and fencing, varying his exercises occasionally, but always keeping them up actively, in the early morning hours. To these he added a severe regimen; no breakfast after his fatiguing exercises, but a cigar to sooth the stomach. Later a breakfast of two boiled eggs, a cutlet with salad and fruit, coffee without sugar or spirit, no bread or wine, but water or tea without sugar to drink; for dinner, no soup, a plate of meat, a dish of green vegetables, fruit, no bread or wine; no dining in the city; absolute self restraint. The result was a fall of his weight to two hundred and twelve pounds, and increased vigor.
An Ideal Jelly-Fish.
A jelly-fish swam in a tropical sea,
And he said: "This world it consists of ME;
Reciprocal Parasitism.—M. Maxime Cornu has taken notice of a prolongation of the vegetative activity of the chlorophyl-cells occurring under the influence of a parasite. M. Schwendener has affirmed that lichens are really fungoid parasites on algæ, which they envelop with their filaments and at the expense of which they live; and his view has been confirmed by the investigations of Rees, Bornet, and Stahl. The principal argument which has been opposed to this theory is based on the difficulty of explaining how the alga continues to live, grow, multiply, and even acquire new vigor, instead of perishing in the toils of the parasite. M. Van Tieghem supposes, to explain this singular circumstance, a special form of parasitism, which he calls reciprocal parasitism. It may, perhaps, be illustrated by the case of the leaf of the maple, which is frequently attacked at the end of the summer by an erysiphus, that occupies the lower surface and fruits there. In the fall the leaves change color and drop off, but the spots occupied by the erysiphus remain green, and so continue, a spot distinct from all the rest of the leaf, for weeks. A similar reciprocation may take place between the algoid and fungoid parts of the lichen.
A Mechanical Rock-Excavator.—By the aid of perforators, worked by compressed air, it has been possible to complete in a few years works of subterranean excavation like the tunnels of Mont Cenis and Mont St. Gothard, which would formerly have occupied several generations of miners. Hand-drilling can be dispensed with when such perforators are used, for the perforator itself makes the hole destined to receive the powder by which the rock is blown up, and the miner has nothing to do but to pick up the pieces. A full solution of the mechanical operation of boring is thus obtained, and a self-acting ventilation of the shafts and the removal of all noxious vapors are secured at the same time. Till recently it was not practicable to apply the perforators in coal-mines charged with explosive gases, for such mines had to be worked without using powder. Two French engineers, Mil. Dubois and Francois, have resolved this difficulty by the construction of an apparatus which they call a bosseyeuse, or, as we might call it in English, a pioneer-drill. Its principal feature is a kind of needle-wedge which is made under the action of the perforator to enter the hole made by the drill and break the rocks up by the force of pressure, without throwing out the fragments as powder does. This apparatus has been used in several gas-infected mines in the Belgian coal-basin, with a considerable consequent diminution in the frequency of
explosions. The powder, if that is used, is introduced when the hole excavated by the perforator has reached a depth of about twenty-seven inches; or, if the mine contains explosive gases, the needle-wedge is substituted for powder. This apparatus, which is represented in the figures (1 to 4), consists of two bars of iron, shaped like segments of a circle, and touching by their ends, the union of which constitutes a cylinder hollowed along its axis with a conical hole. The section of the two segments is of the same size as the drill-hole, so that they fill it completely when inserted in it. As soon as the drill-hole has been hollowed to a sufficient depth, these two bars are inserted in it, and a conical steel needle-drill is introduced into the central hole of the metallic cylinder thus formed. The piston-head of the perforator is then made to strike upon the head of the needle, so as to drive it in like a wedge and cause it to force the two segments apart and split the rock. As many holes may be made as are necessary to break the rock up, and this depends much upon its hardness. Fig. 5 represents a section
of the chamber of a coal-mine, and indicates the position of the holes that have to be drilled to break up the rock in four successive operations. The inventors of this apparatus claim that rock can be broken up with it in veins of the average thickness almost as fast as with gunpowder.
Transmission of Vibrations.—The Transactions of the Seismological Society of Japan contains an account of experiments by Professor H. M. Paul, in Washington, D.C., on the transmission of vibrations from railroad-trains through the ground. Cups containing mercury were fixed at four stations, at distances of from 0·29 to 0·93 of a mile from the railroad, in which the amount of disturbance caused by vibration was ascertained by noticing the displacements of the reflected image of the pole-star. The character of the effects varied according to the distance of the station from the train, the nature of the ground at the station, and the kind of train, but they were distinct. At I one of the stations the communication of vibrations, which were limited to a shallow depth, appeared to be interrupted by the intervention of a ravine. The effect of carriage-driving on a public road was also observed. A hack carrying four persons and drawn by two horses, about four hundred feet away, caused a temporary shaking of the mercury whenever a wheel struck a stone or hollow; and a similar effect was produced while the carriage was crossing a small wooden bridge at about five hundred feet; but no serious continuous disturbance was perceived till the carriage approached within two or three hundred feet of the instrument.
The Systematic Position of the Brachiopoda.—In the "Jenaische Zeitschrift für Naturwissenschaft," Jena, 1881, Dr. Oscar Hertwig and Dr. Richard Hertwig, the eminent embryologists, recognize the work of Edward S. Morse on the Brachiopoda as follows. Having made certain comparisons, they say: "After these analyses, it is self-evident that the brachiopods must be distinguished from the mollusks, and that the two represent perfectly different types of development. It is the merit of Steenstrup to have first recognized this, and indeed, as early as 1847, to have sought a connection of the brachiopods with the annelids. Independently of him, Morse has pursued the same road, and one may say decided the question by comparing, with great ingenuity and to the minutest details, the anatomy of the brachiopods with that of the worms and the mollusks, and has in this connection proved throughout their difference from the mollusks and agreement with the annelids." Gegenbaur also assumed the position of Steenstrup and Morse, and remarks in the second edition of his "Grundzuge" that the brachiopods have little more in common with the mollusks than the possession of a shell quite different from the housing integument of the latter, and form a small and sharply distinguished division, the origin of which may be traced back to the stem of the worm and specially of the chætopod.
Death of Professor William B. Rogers.—Professor William B. Rogers, ex-President of the Massachusetts Institute of Technology and one of its founders, died very suddenly of apoplexy, May 30th, during the exercises of the graduating class of the institution, which he was attending. He had begun making an address, and was reviewing what the institute had accomplished, when he was attacked. He was taken from the hall, and died in about twenty minutes. Professor Rogers was born in Philadelphia in 1805, and was one of four brothers, all of whom have distinguished themselves in science. He succeeded his father, Dr. P. K. Rogers, as Professor of Natural Philosophy and Chemistry in William and Mary College, in 1829, and was Professor of Natural Philosophy and Geology in the University of Virginia from 1835 to 1853. He removed to Boston, where he had since lived, in the latter year. He was President of the Institute of Technology from 1862 to 1868, and was President of the American Association for the Advancement of Science in 1875. He was the author of works on the "Strength of Materials" and the "Elements of Mechanical Philosophy," and of many scientific papers. A portrait and sketch of Professor Rogers were given in "The Popular Science Monthly" for September, 1876.
The Mysterious Volcano of Apo.—The Governor of Davao, Mindanao, Philippine Islands, recently ascended a remarkable volcano called Apo. An expedition to the mountain had often been contemplated before, but had been prevented, partly by the unexplored and difficult character of the country, partly by the opposition offered by the natives, who, though nominally Mohammedans, believe that the summit of the mountain is inhabited by a demon to whom they are accustomed to make offerings when they think he is angry with them, or when they wish him to allow them to collect sulphur. The crater of the volcano was found to be 9,970 feet above the sea, extinct, and covered with vegetation within, although the temperature of the air was but little above the freezing-point. A wide chasm on the southern slope of the mountain was the seat of numerous solfataras, which, furiously spitting out sulphurous vapors with a fearful smell and roar, might well inspire fear in the minds of an ignorant populace. The Tagalaya stream, which rises on the mountain, and in the rough bed of which the ascent was made, brings down lumps of sulphur. A sharp cold prevails in the crater and on the mountain for three thousand feet below it, but the lava and ashes still radiate enough heat to be perceptible, and make one warm who lies down upon them; and, perhaps, to keep up the vegetation which manages to subsist there. Two petrified tree-trunks, which were noticed during the ascent, indicate that a very different vegetation formerly existed there.
Eggs of Reptiles and Insects as Food.—The eggs, even of animals which impress us most Unpleasantly, have their value as food, and seem to be capable of inspiring a relish in the palates of those who have learned to eat them. The eggs of most of the species of tortoises are excellent for eating, nutritious, and agreeable to the taste; and those of the green turtle are held in great esteem wherever they are found. The mother-turtles lay three times a year, depositing sometimes as many as a hundred eggs at a laying, and carefully covering them up with sand, so that it requires an experienced searcher to detect them. The Indians of the Orinoco and Amazon obtain from these eggs a kind of clear, sweet oil, which they use instead of butter. About five thousand eggs are required to fill one of their jars with oil; yet so abundantly are they deposited that about five thousand jars are put up yearly at the mouth of one of the rivers; the harvest is estimated by the acre. Young eggs are frequently found in the bodies of slain turtles by hundreds, in all stages of development, and generally consisting entirely of yolk; they are often preserved by drying, and are considered a great luxury. Alligators' eggs are esteemed by the natives of the regions where those reptiles abound; and Mr. Joseph, in his "History of Trinidad," says that he found the eggs of the cayman very good. The female alligator lays from one hundred and twenty to one hundred and sixty eggs; they are about as large as the egg of a turkey and have a rough, shell filled with a thick albumen. One of the lizards, known as the iguana, is capable of furnishing as many as fourscore eggs, which when boiled are like marrow. The larvæ and nymphæ of ants are considered by many people a choice relish when spread upon bread and butter, and are said to be excellent curried. In Siam they are highly esteemed, and are so valuable as to be within the reach only of the rich. In some parts of Africa, where ants swarm, they are said to form at times a considerable proportion of the food-supply. They are used in some countries of Europe for making formic acid, and are subject to an import duty. The eggs of insects belonging to a group of aquatic beetles are made in Mexico into a kind of bread or cake called, hautle, which is eaten by the people, and may be found in the markets. They are got by means of bundles of reeds or rushes, which are put in the water and on which they are deposited by the insects. Brantz Mayer, about forty years ago, noticed men on the Lake of Tezcuco collecting the eggs of flies which, he says, when cooked in cakes were not different from fish-spawn having the same appearance and flavor. "After the frogs of France and the birds' nests of China, I fancy they would be considered delicacies, and I found they were not disdained on the fashionable tables of the capital." According to the report of the Commissioner of Agriculture for 1870, the larvæ of a large fly which frequents Mono Lake, in California, are dried and pulverized and mixed with acorn-meal and baked for bread, or with water and boiled for soup.
Sanitary Inspection of Houses.—Mr. Lewis Angell, Sanitary Inspector of West Ham in Essex, an outlying district of London, says, in illustration of the prevalence of sanitary defects even in the best houses, and of the need of thorough inspection, that in the civic palace of the Lord Mayor or of London, "three quarters of an inch of floating fungi scurf was recently found on the surface, and three eighths of an inch of mud at the bottom of the cisterns, while a bottle of water on his lordship's table contained hundreds of nematoid worms." Offensive mud and animal organisms were also found in the cistern of the Athenæum Club, St. James. We habitually defy disease when we leave the doors of our closets open and the windows shut. The reverse ought to be the practice. He believes that sanitary science should be put on a par with literary and mathematical studies in the schools, and that public and official inspection should be provided for everywhere, the expense in the care of new buildings to be met by fees charged upon the owners and builders, who expect to derive a profit from them. He commends what has been done in Chicago in the official inspection of tenements, and the official supervision of plumbing that has recently been adopted in New York.
The Screw-Propeller.—The people of Boulogne, France, have recently set up a statue of Frédéric Sauvage, to whom they ascribe the invention of the screw-propeller. He devised a means of propulsion by screws in 1832, and offered it to the French Government. A commission reported upon it that it might be employed with advantage for small boats, but would be of no use for large vessels. The English Government tried to buy the invention exclusively for England, but Sauvage refused to sell it on such terms. It was applied to a steamer in 1841, after plans furnished by Sauvage, but the builder and engineer of the vessel took all the credit for it. After an experience in the debtors' prison, and then spending $16,000 in experiments during ten years, Sauvage passed the last years of his unfortunate life in the Picpus asylum. The priority of his invention is disputed in behalf of several Englishmen: of James Watt, who proposed to use a screw in 1770; of Edward Shorter, who patented a propeller in 1800, and applied it two years afterward; of Stevens, in the United States, who tried to drive a boat by a screw in 1801; of Trevithick, who invented a screw-propeller in 1816; and of Samuel Brown, who used one in 1827. F. Pettit Smith, to whom more than any other person we owe the use of this motor, never claimed to be its inventor, but only that he placed it in the dead-wood of the vessel. The "Revue Scientifique" claims the credit of the invention for Charles Dallery, who obtained a patent for a screw-propeller and a tubular boiler in 1803.