SCIENCE NOTES.

Otago Witness, Issue 2360, 18 May 1899, Page 54

SCIENCE NOTES.

— Astronomers know that the sun, accompanied by the earth and the other planets, is moving toward a point in the northern heavens with great speed. Just what the velocity is however cannot be told with certainty. Professor Simon (Newcomb, in a recent lecture, said that it was perhaps between five miles and nine miles per second. The bright star Alpha iLyrae lies not far from the point toward ,which the sun is moving. Every moment ,we are getting nearer to the place where that star now is. As to when we shall get there, he says: "Probably in less than a toillion years ; perhaps in half a million." " — Uuder the title " L'Homme et le Singe," the Marquis de Nadaillac, in the Revue dcs Questions Scientifiques, criticises ,the alleged descent of man from the anthropoids. "He points out forcibly," says Dr D. G. Brinton, in" Science, " how many assumptions, without positive support, underlie the. general theory of evolution, and especially tire evolution of man 1 froni any known lower type. As the same time he does not- pretend that, our present knowledge is.decisive, .cither for the negative or the affirmative." "At the present time," says Nadaillac, ' in vjew of what is actually known, we are not prepared to deny the possibility of 'any such theory; but, 1 hasten to add, we are just as little prepared to affirm it as a truth." "Such caution," Dr Brinton adds, "is certainly m season, as the tendency is constant to hasty conclusions." — A fact noticed and mentioned by Professor Koch during hie studies in Africa and

India is that women stand malarial climates far better than men. During the appalling mortality on the Gold Coast within the past four years, there was hardly a death among the women living out there, while every kind of man was dying — men new to the tropics, men borne in them, men who had been accustomed to them for years, even men who had battled with the ravages of' West Africa for upwards of ten years. The attempt to explain this anomaly by the fact that men are, as a rule, more exposed to the hot sun of day and the miasma of night failed in presence of the fact that the death rate was highest among officials, merchants, and employees who work- in offices, banks; • and warehouses, where no exposure to weather is involved, and where medical attendance, food, and all conditions of living are the best obtainable in that country. The fact that black water fever, so deadly to male Europeans, hardly ever attacked women, and ,that no physician has yet offered any reasonably conclusive explanation of such discrimination, illustrates how far medical science is yet from a full understanding of malarial disease.

— The falling out of ornaments embedded in wood, where a visible screw is not desirable, is frequently very troublesome, and a renewed gluing in rarely obviates the evil, if it is omitted to dip the metal pieces previously in weak nitric acid for about half a minute. Such a bath, with subsequent drying, imparts a moderate roughness to the metallic surfaces, which makes the glue "seize" much better. The glue employed must be exceedingly viscous and never brittle. It is prepared as usual, and receives a small addition — about a teaspoonful — of glycerine, and as- much of slaked lime during the boiling of the mixture should be stirred together intimately, so that the admixtures can properly combine with the. glue- It should be applied hot on the slightly warmed pieces, which should be quickly pressed intc the wood. The glue must not be thin, but syrup-like. Metal objects inlaid in this manner never drop out from the wood ; they can only >.c torn out by force, on which occasion a thin < layer of -wood is carried along. — Zeitschrift fur Drechsler.

THE FUTURE OF THE EARTH.

According to the ideas of astronomers the earth was detadied from the solar nebula, and, nfter being a miniature sun,"' was condensed by cooling. Losing its heat by radiation in space, the fiery globe became covered with a solid, dark crust. The solid layer then acted as a barrisr to the radiation of the molten mass beneath, for rock lias a feeble conductive power. The sun, then, is the sole source of heat that has supported, and that jet supports, Uie

terrestrial surface. On the formation of the solid crust, the -water vopour diffused throughout the atmosphere condensed little by little, and water accumulated in the first depressions of the surface. Thus were formed the~first oceans, in which life was soon to manifest itself in the most rudimentary organised forms. While these forms went on to develop into more perfect types, distributed uniformly over the globe, the cooling of the earth continued ; foldings resulting from its contraction appeared on the surface, and its internal activity showed itself, at intervals, in various regions in the form of volcanic eruptions. The earth's profile thus became more accentuated by the elevation of mountains and the lowering of the first oceanic depressions. It is probable that vegetation then appeared on the first continents, whose temperature must have been tropical. But the outline of the surface did not depend solely on the contraction of the earth's crust, but also on erosion, due to atmospheric agencies. "While the contraction, by lateral folding or vertical depression of layers, raised or lowered considerable portions of our planet, erosion produced an inverse effect, since by the action of rain, ice, and variation 'of temperature, it disintegrated the rocks and reduced them to powder, which it transported and heaped up in the depressions of the "ciust. Consequently contraction accentuates, or. at least preserves, in one- form or another, the relief of the surface, which denudation is working to obliterate. The resultant of these two opposite agencies gives us the form of the globe at any given moment.

In the course of geologic time contraction formed mountain chains. The first mountains, which were as high as those of today, have in great part disappeared by erosion ; there remain only fragments, which the study of geology alone enables tis to identify. As cooling continued, climates became differentiated, and to the lower plants and the invertebrate animals succeeded higher forms : fishes, reptiles, birds, mammals, and finally man. The human species had not yet appeared on the earth when the Pyrenees, the Alps, the Carpathians, and the Himalayas were formed. These are a part of the same mountain chain, whose relief is in great degree preserved, because it is the most recent, chain, and the action of time has altered it least. As long as contraction shall continue, there will be mountain chains, a very accentuated relief, continental masses, and consequently an easy flowing of waters to the sea. But when by cooling the crust shall become sufficiently thick and solid to prevent lateral folding, mountains' will no longer be formed, and then, as denudation alone will, act, it will level- the "surface little by little. Then, by the partial filling of the oceanic basins, by the greater and greater difficulty of flow (due to lack of slope)' of water toward the sea, the continental masses will be divided, by channels of greater or less size, into true archipelagoes. At this time there will be on the earth no more water surface than at present, but this water will be differently distributed. Nothing shows that at this period, far in the future, life will be impossible on the earth. Nevertheless, although the essential elements of air and water will not be lacking, cold will certainly bring about a change in the character of life, ani a partial disappearance of living creatures from its surface.

M. Dollo asks whether some other planel may not have already reached the stage that we have just predicted for our globe 'C There is one, in fact, the planet Mars, of oiu- own solar system. After the earth shall have reached the phase represented to-day by Mars, what will, become of it? Instead of consisting of a crust and a fluid nucleus, it will be completely solid. It will then absorb into its crevices the whole of its air and its water. This will easily occur, for experience shows that for this it will be sufficient to be only one-third as porous and only one-hundredth as full of fissures as the granites that are now traversed by millions of veins of harder rock. These fissures, which can no longer be filled with molten rock from the depths of the earth, will be occupied by water. If life has not already ceased by this time, it will then be no longer possible. And after this? Afterward, the fissures will increase as the mass contracts further, and the earth, cracked, dislocated, and finally broken into pieces, will rush through space"as a shower of meteorites. The fissures observed on the moon's surface and the meteorites, that fall on our globe enable us to believe in such a future .state for the earth. Such, briefly summed up, are the series of phases through which our globe has passed and probably will pass.