Page:Littell's Living Age - Volume 131.djvu/774

768  after the appearance of Prof. Tyndall's work on glaciers, the Bologna professor, Bianconi, observed that, while Tyndall's experiments certainly prove that rapid changes of form in ice are due to crushing and to regelation, they do not prove at all that ice is devoid of a small degree of plasticity, which degree might be sufficient to explain the plasticity of glaciers. He undertook, therefore, a series of experiments (described and published in 1871 in the Mem. of the Acad. of Bologna, 3rd ser., vol. i.) on planks and bars of ice submitted to bending and torsion. The bending of ice-planks having been afterwards the subject of researches of Messrs. Mathews, Moseley, Tyndail, and Heim, it will suffice to say that Prof. Bianconi, making his experiments at higher temperatures (from plus 1° to plus 5° Cels.), observed a still greater plasticity of the ice than that obtained by the experiments made in England and Germany at lower temperatures. These experiments proved that slow changes of form of the ice may go on without any crushing and regelation, and that ice enjoys a certain degree of plasticity notwithstanding its brittleness; the ice-plank can, indeed, be shattered to pieces, during its bending, by the slightest shock. Now, Prof. Bianconi gives in the Journal de Physique for October the results of his further experiments on ice, much like those of Heim, or, yet more, those of M. Tresca on the puncheoning of metals. Granite pebbles and iron plates are slowly pressed into ice at the same temperatures, and not only do they penetrate into it as they would penetrate into a fluid or semi-fluid, but also the particles of ice are laterally repulsed from beneath the intruding body, and form around it a rising fringe. Moreover, when a flat piece of iron is pressed into the ice, the fringe rising around it expands laterally upon the borders of the piece, and tends thus, as in fluids, to fill up the cavity made by the body driven in. These experiments tend thus greatly to illustrate the plasticity of ice; but it would be very desirable that M. Bianconi, if he continues his researches, should accompany them by some measurements (as has already been done by M. Heim) in order to obtain numerical values of the plasticity of ice under various circumstances.

have to announce with great regret the death of another martyr to science. In a letter, dated September 15, the Rev. S. McFarlane writes from Somerset, Cape York: "We have just heard of the massacre of Dr. James and his partner, a Swede, at Yule Island by the natives of New Guinea. They had gone in their large boat to the east side of Hall Sound to shoot birds of paradise, when they were attacked by three canoes, and both white men were killed. The native crew managed to get away in the boat, and brought the sad news here." Dr. James was a young American who had been collecting objects of natural history in Yule Island and on the opposite shores of New Guinea. His first collections arrived in this country about a fortnight ago, having been sent over by his friend, Dr. Alfred Roberts, of Sydney, to whose liberality the expedition was greatly indebted. The excellent way in which the specimens are preserved and the careful notes given by the collector show that Dr. James was enthusiastic in his work, and it is melancholy to think that so promising a scientific career has been thus prematurely cut short. A description of the collection of birds formed by the late traveller will be given by Mr. Bowdler Sharpe at an early meeting of the Linnean Society, in continuation of the articles on the avifauna of New Guinea, commenced during the last session of the society.

— M. Montigny has continued his researches on this subject with especial reference to the influence of the approach of rain on the twinkling of the stars. Eighteen hundred observations referring to seventy stars have been discussed, two hundred and thirty nights having been devoted to this work with the scintillometer, already described in these columns. The conclusions at which M. Montigny arrives are as follows: — 1. At all times of the year the scintillation is more marked under the influence of rain, 2. Under all circumstances it is more marked in winter than in summer, and also in spring than in autumn for wet weather; in dry weather the spring and autumn are nearly equal in this respect. 3. Scintillation varies with the atmospheric refraction. 4. The approach of rain, and especially its continuance, affect the intensity of scintillation. 5. The amount of rain is always greater on the second of two days than on the first, but it is less in winter than in summer, and the more marked scintillation in winter results, therefore, from the increased density of the air due to the low temperature and high barometer. Similar conclusions are arrived at by grouping together the observations according to the intensity of scintillation, eighty-six per cent of the days with very marked scintillation being under the influence of rain. The twinkling of the stars appears also to be very marked in windy weather, and strong scintillation is a sign of an approaching storm, the colors being more decided in the case of rain, and accompanied by irregularities in the image. It is to be remarked that this is the case notwithstanding the fall in the barometer corresponding to a decrease in the density of the air, which would naturally diminish the scintillation. As might be expected, the altitude at which twinkling first becomes sensible is increased by the approach of rain. 