METEORIC DUST.

Hawke's Bay Herald, Volume XXI, Issue 5336, 21 March 1879, Page 2

METEORIC DUST.

Mb Oowpbr Ranyard has made a communication to the Astronomical Society on meteoric dust, in which he t hasr thrown out some interesting, speculations as' io the explanation of the relative distribution of land and water on the globe and as to geological climates; ! He says that meteoric idust* exists . to >a; much greater extent, than was formerly suspected. In 1867 Dr Philson published the result of many experiments, in , many countries, which showed that,' by exposing a sheet of glass covered with pure glycerine to a strong wind, ho has collected on it black angular particles, which tie hasy .by chemical tests, found to be iron. It 'is, however, only in the winter, months he has found this to be the case. In 1871 Dr Nordenskjold collected by a magnet meteoric iron particles,- from snow which had fallen near Stockholm.^ In 1872 he collected much of it from show lying on ice' in Finland. The Arctic Expedition of 1872 had opportunities ,of y . collecfing snow far removed from human habitations, and they found large proportions of magnetic particles. M. Tissandier, in 1874-5-6, published in the Comptes Bendus a series of papers on atmospheric dust, in which, among other tilings, he has alluded to the iron found in the dust collected in the towers of Notre Dame. Again, Dr. Walter Plight published in the Geological Magazine in 1875 a paper in which he collected the evidences lof iron "dust " found in holes in the ice in Greenland. In 1876 Mr John Murray published a paper in the "Proceedings of the Royal Society of Edinburgh," in which he gave an account of his examinations of 'the bottoms of the oceans and seas visited by Her Majesty's ship Challenger. .In many of the deposits magnetic particles were found. It was suggested that the nickel present prevented oxidization, while the fact that the meteoric particles which had fallen into the sea had not been washed away was attributed, ,to the water being deep and not near the scourings of land surfaces which would cover it up. Again, in 1876 M. Yung examined the iron particles found in the snow which had fallen at the Hospice of ' St. Bernard. Mr Ranyard submits that all these facts go to show that meteoric matter falling, in the lapse of ages must materially contribute to the matter of the earth's crust. In the course of a year millions of meteors enter the earth's atmos- \, phere. Most of them are '/consumed" in the higher regions, but many particles reach the earth without having undergone change. There is little' donbti that high above the earth's surface the air is impregnated with dust. The researches of Von Niessl show that many of the meteoric masses enter the earth's atmosphere in directions indicating that they do not belong to our solar system. It is therefore probable that a tarja

quantity of meteoric dust is derived from sources outside our system. The earth and the plantes as they sxa- carried along' with the sun in its motion through space ■would thus receive a larger proportion of meteroic matter on their northern than on their southern hemispheres, and Mr Ranyard suggests that this may account for the preponderating mass of the continents in the northern hemisphere of the earth and for the fact that the great peninsulas all taper to the souths Another important inference to whicfyMr Ranyard directs attention is that it is known that when meteoric masses are heated large amounts of occluded gas are given off. One of the results from a continuous fall of meteoric matter is that gaseous matter is probably being continually added to the atmosphere. According to whether the earth were passing through a region of space in which there are many or few meteors, the height of the atmosphere would be increased or deoreased. When decreased, the temperature at the sea level would be that of our mountain tops and a glacial period would result. When increased, the temperature would probably be like that of the carboniferous period. — Times.