Popular Science Monthly/Volume 51/September 1897/Fragments of Science

Fragments of Science.

Ups and Downs of the Tussock Moth.—After the English sparrows had quite exterminated the voracious measuring worms that used to make our city trees naked, the uneatable tussock moths took advantage of the opportunity and filled the trees for a few years with their uneatable larvæ. Now the tussock moths have nearly disappeared, and A Study in Insect Parasitism, by L. O. Howard, entomologist of the Department of Agriculture, tells us how it came about. It appears to be a kind of process of Nature that as soon as any living thing becomes numerous parasites find it, and shortly reduce it to its normal proportions or below. These in turn are subject to secondary parasites which keep them in check. Thus twenty one parasites have been found upon the tussock moth, with fifteen hyperparasites. While, after having passed its culmination in the farther Eastern cities, the proportion of tussock moths has been about the same, it took a rapid and enormous increase in Washington in 1895. But the parasites appeared in force with the third generation of that year; and when in September several species of trees had been cleared of leaves and others badly injured, "it was an exception to find a healthy caterpillar which one of them was not engaged in stinging." There was a moderately abundant hatching of Caterpillars in 1896, but the parasites were ready for them, and the first generation was practically exterminated by them. In the later months of 1896 the hyperparasites took their turn, and the tussock-moth caterpillars were not so hard to find, but were still rare. Even where parasites do not step in to keep down increase, the excessive multiplication of animal pests is at length inevitably checked by disease. Thus the chinch bug has no parasites, "but when it increases beyond the bounds of what may be called Nature's law, for want of a better term, bacterial and fungous diseases speedily carry it off."


Objects of National Forestry.—The policy and aims of those who are seeking the establishment and maintenance of a national forest policy have been misunderstood and misrepresented; and the misapprehension has been strengthened by some glaring defects in some of the forest laws, which the friends of forestry do not approve and desire to have remedied. It is not by their work, but contrary to their intentions, that these laws embody no provisions by which citizens can obtain wood from the public domain by purchase, and that timber-stealing flourishes under their operation. The laws which they propose are designed to remedy these evils. Reservation is the first purpose sought in them, regulation of the use of the timber the second; perpetuation of a valuable resource for coming generations the object. The programme of those urging these laws, as defined by Mr. B. F. Fernow, chairman of the American Forestry Association, is to withdraw from sale or entry all lands not fit or needed for agriculture and to constitute as objects of special care by the Government the lands at the head waters of streams and on mountain slopes in general; to permit prospecting, mining, and other operations under such regulations as will prevent unnecessary waste, and to cut and sell the timber under such methods as will secure perpetuation and renewal of the forest growth; to provide for protection against fire, theft, and unlawful occupancy; to respect all existing vested rights and arrange an exchange, if necessary, for private lands included in reservations; and, finally, to restore to the public domain for entry all lands that are found in the reservations fit for agriculture. The interests of the miner, the lumberman, the settler, and every citizen in the present and the future are regarded in the policy they advocate; the free herding of sheep, by which forest tracts are destroyed and rendered unfit for renewal, being the only industry not considered. "Just like the proverbial incompatibility of the goat and the garden, the growing of wool and wood on the same ground is incompatible."


Sewage Purification by Filtering.—Filtration through the soil is regarded by M. Vincey, of the French School of Agriculture, as hygienically and economically the most perfect. The work is done through the nitric oxidation of nitrous organisms effected, independent of vegetation, by special microbes contained in the soil. The nitrates thus formed, combined with the very soluble bases contained in the earth, are taken up as foods by plants or carried off in drainage waters. The purifying quality of the soil is not augmented by the production of crops upon it. The siliceous sewer beds of Gennevilliers, near Paris, dug up and ridged, without crops, are capable of absorbing and purifying 1,200,000 cubic metres of sewage per hectare (about two acres and a half) a year. Agriculture is regarded as of great importance in the economy of sewer beds, but not so much on account of its relations to purification as to the quantity of water which the ground can receive. The demands which the most thirsty crops can make upon the water constituents of sewage are, however, limited; and they absorb only a fraction of the amount poured upon the beds. M. Vincey's observations in the Agricultural Park of Asnières indicate that forest land is capable of usefully purifying at least as much water as the natural meadow; and it results from all the experiments that, for a like soil and equal volumes of sewage, a smaller surface of meadow or forest is required than, for instance, of kitchen-garden crops. Siliceous soils and sands free from marl appear to have the highest purifying qualities. Limestone formations, marls, clays, etc., are inferior in these properties. The longer a soil has been purifying sewer water, the fitter it becomes for continuing the work; for purifying irrigation multiplies the colonies of mineralizing ferments in the soil. Comparative examination of land in which the operation had been going on from ten to twenty years and of soil that was virgin to the process, showed that no nitrogen had accumulated in the earth in consequence of sewage irrigation. The smaller part of the mineralized matter passes into the crops, while the larger part is washed away.


Cycles and Dogs in War.—The utility of bicycles in military art having been demonstrated, men of war are now studying the means of contending against them and their riders. The mere overthrow of the instrument does not convey any great advantage, for the man is there, and possibly still standing, armed, and ready to fight. Dogs have so far seemed to be the most effective agents in this contention, and the large Danish dog has been selected as the animal most fit. About a thousand dogs are said to be under training in Berlin for this sort of warfare. They are taught to distinguish the uniforms of friends—German, Austrian, and Italian—from those of the enemy—French and Russian—and attack the latter, the legs of the sham "hostile" soldiers being well protected, of course, by stout buskins. As all the armies will have cycle troops, they will all have to have their trained war dogs; and then, when the attack has commenced, La Nature slyly intimates, and the dogs get mixed with the cyclists, they will leave the soldiers and go to fighting one another.


Hydraulic Blasting.—A meeting of the Manchester Geological Society is reported in Industries and Iron, at which a new hydraulic apparatus for breaking down coal in mines was discussed. Mr. James Tonge, who described the apparatus, called attention to the great danger attending the ordinary method of blasting in coal mines, and said that the numerous serious accidents from this cause had led the inventors to look for a safer process of loosening the coal. The new apparatus consists of a hydraulic cartridge, eighteen inches in length and three in diameter, and weighing thirty pounds, and a small but powerful hand pump fitted with a pressure gauge weighing about twenty pounds. The mode of using it is as follows: The coal is holed underneath the usual depth, and a hole drilled near the roof to about the same depth as the holing, in the same way as for blasting. After this the cartridge is placed in the hole and pushed to the back. No "stemming" is required. The pump is coupled to the cartridge, the suction pipe placed in a small bottle of water, and work commences. Very soon the gauge begins to show the rising pressure—half a ton, a ton, a ton and a half, two tons to the square inch. During this time a cracking sound is heard, indicating the shearing off of the coal at the back. The gradual way in which the work is done, without shock or jar of any kind, prevents even the least damage to coal or roof, in striking contrast to the action of explosives. The time occupied is an important matter. It has so far been about twelve minutes. This time includes placing the cartridge in the hole, connecting to the pump, getting down the coal, withdrawing the cartridge from the hole, and getting to the next place. The advantages claimed for this process over the ordinary blasting are (1) larger and stronger coal, which means a better average price; (2) non-interference with the working of the pit, the coal being got down whenever required; (3) no damage to roof; (4) no dust; (5) and absolute safety from the dangers attending shot firing. In previous machines of this sort trouble has been had with the joints, but it is stated that this one is free from that fault.


Timbuctoo and Jene.—Mysterious and romantic visions of wealth and gayety have been associated for centuries with the name of Timbuctoo. Of numerous travelers who have ventured much to reach the city only a few have succeeded. Thus, according to a summary in the London Academy, Mungo Park visited it in 1805, but was drowned in the Niger shortly afterward. Major Laing reached it in 1825, after a three years' expedition across the desert, but was murdered on leaving it. Rene Caillie found it about the same time, and wrote a book about it. Davidson was murdered, and Richardson died in the desert on the way thither. Dr. Bart found his way into the city, but never stirred out of doors while there. Lenz visited it and wrote a description of his adventure. The late Joseph Thomson was planning a visit to Timbuctoo when he died. Now the Frenchman, Félix Dubois, has published one of the best descriptions we have of the mysterious city. Its position on the edge of the Desert of Sahara, and at the top of the great bend of one of the largest and most constantly navigable rivers of the earth, the Niger, defines its importance. Yet M. Dubois found it not the greatest or most interesting town in the region. It is surpassed by Jene, whose name is echoed in the Anglicised form Guinea. That city dates from the seventh century; was built, not by negroes or negroids, but by the Songhis, who migrated from Egypt across the Soudan more than twelve hundred years ago; and has wonderfully solid architecture of the Egyptian order. The present inhabitants of Jene, M. Dubois says, "resemble a palimpsest on which the first manuscript is dimly decipherable. Their oral traditions, their chronicles, and their dwellings all betray their Nilotic fatherland."


Three Masters in Science.—We merely mentioned, last month, the deaths of Prof. Julius Sachs, the botanist, and Prof. Carl R. Fresenius, the chemist. Prof. Sachs was best known by his Text-book of Botany, which is one of the standard works of the science, of first authority. He was also author of the Experimental Physiologie, a work of corresponding importance in its field, a history of botany, and a collection of lectures. He was born at Breslau, Germany, in 1832, and died at Wurzburg, May 29th. His first teacher was Purkinje. He taught at Prague, Marandt, Chemnitz, and Poppelsdorf, near Bonn, and was Professor of Botany at Freiburg and Wurzburg. The fame of Fresenius dates from so early a period in the century that one would be almost inclined to reckon him as of a past generation. He was born at Frankfort-on-the-Main in 1818, began the study of natural science very early, entered the University of Bonn in 1840 and that of Giessen a year later, and became Professor of Chemistry, Physics, and Technology at the Agricultural Institute in Wiesbaden in 1845. He was identified with that institution for the rest of his life. His best-known works are the Qualitative Analysis and the Quantitative Analysis, published in 1841 and 1846 respectively, which have passed through very numerous editions and have been translated into nearly every European language. M. Paul Schutzenberger, an eminent French chemist, died June 26th, at Mézy, France. He was born at Strasburg, the son of a lawyer, in 1829; studied medicine and then chemistry; was made professor of chemistry in the high scientific school at Mulhouse; then became adjunct director of the chemical laboratory of the Sorbonne and chief of chemical work in the Collége de France. In 1876 he was named titular professor of chemistry in this institution. For many years he directed the physical and chemical school of the city of Paris. He was a member of the Academy of Medicine and the Academy of Sciences. His principal works were on the application of chemistry to animal physiology, coloring substances, fermentation (in the International Scientific Series), and the Traité de Chimie Générale, in seven volumes.


Primitive Drills.—We all know how difficult it is, even with the best tools we have, to bore a correct hole by hand in a hard substance. Vastly more difficult must this have been with primitive men, who had no tools except flints and bones and sticks. Yet, as Mr. J. D. McGuire observes in his study of the Primitive Methods of Drilling, the earliest remains of man are found associated with implements of his manufacture in which holes have been artificially perforated, the implements consisting generally of bone, ivory, or shell. During the cave period man had the implements called "batons of command," the use of which is unknown, which were bored with extreme care from reindeer horn, and are often carved with representations of animals or of man, often artistically done. These men could only fashion the rudest implements from chipped stone. At later periods of development beads of shell and stone were made of shapely forms and evenly perforated. Of such are the Indian wampum beads, which, according to Lawson's History of North Carolina, they managed "with a nail stuck in a cane or reed. Thus they roll it continually on their thighs with their right hand, holding the bit of shell with their left, so in time they drill a hole quite through it, which is a very tedious work." This describes the most primitive form of drill, except that men had not yet advanced to the nail. They used flints or bones or sticks, re-enforced with sand. Mr. McGuire's presentation of objects perforated with this sort of drill exhibits some spocimens of fine work done in hard stone and applied to various purposes. The next development is the strap drill, in which a string or cord is wound around the stick, and when pulled back and forth produces corresponding alternations in the motions of the drill, and adds considerably to its power. To this was added a bow, the pulling and relaxing of which maintained the revolution of the instrument. An improvement on this was a disk, the momentum of which carried on the motion of revolution, and rewound in an opposite direction the string which had been unwound. When the bow was arranged so as to have an upward and downward motion on the stick, the pump drill was constituted, an instrument differing essentially from all other boring tools, relatively easy to work, which has been widely distributed. The Egyptian monuments bear frequent representations of the use of the bow and disk drills under different forms and with various modifications. The Egyptians, however, had copper and iron.


Birds and their Songs.—Whether birds inherit their song or learn it by imitation has been the subject of experiments which M. Flamel describes in La Nature. We know already that some species take up the songs of others, but it had not been determined whether they ever learned them at the expense of their native song. One of M. Flamel's correspondents had a sparrow, "brought up by hand," which, when put into a cage with finches and canary birds, took up the songs of all its companions, repeating them perfectly; and then, some captured crickets having been placed near it, adopted their chirp too, but never sang like a sparrow. Another correspondent was told by a gamekeeper of two linnets which he had taken from the nest when they were very young and kept at his home in a wood where there were no other birds of their species, but nightingales were abundant. The birds sang like nightingales. Of the somewhat varied repertory of songs of a certain species of linnet, this correspondent asserts that the songs are severally peculiar to certain well-defined localities. All the individuals in one of these districts have the same songs and the same number of songs, so that the fanciers in the city where he lives are acquainted with the songs of the several stations around and know just where to go to get birds to their liking. It follows from this that some birds, at least, learn their songs by imitation.


Sunlight and Bacteria in Rivers.—In view of the destructive effect of sunlight, especially of the blue to the ultra-violet rays, upon bacteria in water, Prof. H. Marshall Ward would explain the comparative freedom of river waters under the blazing hot summer sun from bacteria as against the more abundant infection of the same waters in winter. Pasteur and Miquel found that the germs floating in the air are for the most part dead—killed, the author holds, like the germs in the air of the Alps, by the sun. Yeasts which normally vegetate on the exterior of ripening grapes are destroyed, according to Martinaud, if the heat be very intense; and Giunti has observed that the ingress of sunlight hinders acetic fermentation—a bacterial process. So the access of light appears to be inimical to the germination and develment of fungi of various kinds. The destructive rays may be cut off by color screens, and the protected germs can then sprout and develop as easily as if no light was playing upon them. Such color screens appear to the author to be common in Nature, where the spores and tender growing cells are compelled to begin their vegetative processes in the light. The green chlorophyll screen of ordinary plants may fulfill this purpose. When the typhoid bacillus falls into turbid, dirty water in summer, it finds a congenial propagating place. The dirt furnishes it food, absorbs heat to increase the warmth, and keeps off the hostile blue and violet rays.


The Appraisal of Books.—The subject of furnishing librarians and the public with some general, comprehensive guide to the character and real value of books is discussed by Mr. George Iles in a paper on The Appraisal of Literature, which he presented to the International Library Conference held in London in July. The task of selecting from the enormous mass of books now appearing daily to be bought or read is a bewildering one. How make it easier? Mr. lies would reach the end.by a system of shortened reviews, prepared and adjusted for the purpose—"a brief note of description, criticism, and comparison, written by an acknowledged authority, signed and dated, and placed where the reader can not help seeing it, both within the lid of the reviewed book itself and on a card next the title-card in the catalogue." If the book treats of a question in debate, fact and opinion should be carefully distinguished, and views of opposed critics might be presented. By this means the inquirer would know which book is best, or among the best of its kind; would be made aware of defects; would learn how one book can gainfully piece out another; and would gather indications of the periodicals or transactions which bring a story of discovery and research down to date. In a final line he might be told where detailed reviews are to be found. Persons qualified to undertake this business of appraisal might be found among professional reviewers, who could "boil down" their larger reviews and adapt them. The work might be placed under the direction of a central superintendency of the American Library Association; and in connection with it something might be done "to rescue from neglect the great books which, from such causes as the untimely death of their authors, or the sheer brunt of advertisement, are overlaid by new and much inferior writing." Starts have been made toward this work in such manuals as the Reader's Guide in Economic, Social, and Political Literature, the List of Books for Girls and Women and their Clubs, and the special lists of books on fine art and on music.


Man's Language to Animals.—The exclamations we use in driving and calling horses, oxen, cats, dogs, fowls, and other domestic animals are presented by Prof. H. C. Bolton in a paper on the subject as affording familiar illustrations of a language of peculiar characteristics, whose words are chiefly monosyllabic and dissyllabic, and usually repeated in groups of three, utterly devoid of grammar, exclusively in the imperative mood, and consisting of words not found in the dictionaries, which serves as a ready and sufficient means of communication between man and the many races of animals under his subjection. It has little in common with the language used by the animals themselves, but is forced upon them by man and made comprehensible to them by constant repetition. The terms used are different in different countries. In thus controlling the actions of domestic animals by the voice, man makes comparatively little use of the language by which he communicates with his fellow-creatures, but employs a peculiar vocabulary, a variety of singular terms comprising inarticulate sounds and musical calls, whistling, chirping, clicking, and other sounds not easily represented by any combination of letters of the English alphabet, or by musical notation. Prof. Bolton has collected these words from a considerably large number of languages, ancient and modern, describes them, and analyzes them so far as they are susceptible of analysis. He reaches the general conclusion that the terms are mostly corruptions of the ancient names of the animals, sometimes with a prefix signifying "come," with expressions that have become otherwise obsolete. They are all subject to the same influences that lead to the development of dialects, and, the language being unwritten, the changes are quite radical. An important feature mentioned, but not dwelt upon at length, is the musical intonation giving a special character often associated with the call. We are surprised that while the author says much about "puss" as a call for the cat, he does not even mention "kitty," which is used a hundred times as often.


Plants and their Insect Inhabitants.—Plants have a special interest to the entomologist according to the number of insect species they harbor, and the invasion which causes dismay to the gardener brings him joy—qualified, we are glad to say, if the plant is a valuable one, by sorrow for his neighbor's trouble. Miss Mary E. Murtefeldt, of Kirkwood, Mo., has found no better way of making the acquaintance of the insect fauna of a locality than to take up, one after another, its native or introduced plants and, keeping them under close observation from spring till fall, and perhaps for several successive years, note the species that visit them and the larvae that subsist upon them, either exclusively or in common with other plants. Many weeds afford abundant harvests of this kind; one of the most productive of them is the cut-leaved ragweed (Ambrosia artemisiæfolia) of roadsides and fallow fields, every part of which—foliage, flower, leafstalk, stem, and root—sustains its own peculiar species, the majority of which do not occur on other plants. This plant is especially a mine of wealth to the micro-lepidopterist in the number, beauty, and variety of the species that are partially or wholly dependent upon it. Miss Murtefeldt names between forty-five and fifty species of five orders which she has found on this one plant. Perhaps one fourth of these are limited to the genus Ambrosia, and six or seven have been found only on artemisiæ folia.