to the conclusion that there is such a thing as a cosmical dust, and that this form of matter, subtile as it may be, is by no means without effect in the operations of the universal scheme. The inconceivably rapid growth of the tails of comets directed away from the sun, and the mighty sweep of their movements, seem inconsistent with the direct flight or passage of cometary particles, and the effect is now rather explained on the hypothesis that matter already existing, diffused through space, may become in some way electrically polarized and rendered luminous through the mutual action of the sun and the comet. A recent writer suggests that "these polarized particles, or molecules of vapor, require time to become depolarized and to lose their luminosity, which fact may at least in part account for the breadth of the illuminated space or the apparent spread of the tail." The earth is believed to have passed through a portion of the tail of the comet of 1861. On the 30th of June its distance from the earth was rather less than 13,000,000 miles, and its train was computed to be 20,000,000 miles in length. The positions were such that it is quite possible that, on the evening of June 30th, the earth might have been involved in the tail, while certain unusual phenomena of an electrical nature were actually observed at that time. The writer on "Comets," in Brande's "Cyclopedia," says:
"It is a remarkable and significant fact that, not only in various parts of England and Ireland, but also in Spain, Italy, Switzerland, and other Continental countries, a very peculiar phosphorescence, or illumination of the sky, was perceptible during the early hours of the night in question, which many persons supposed to be caused by the aurora borealis, unusual as the phenomenon is In the summer months, especially in the south of Europe; at the same time it was remarked that the luminosity of the sky did not resemble the usual effect of the aurora, but was something quite exceptional. We incline to attribute the phenomenon to the presence of cometic matter (if matter it can be termed) in our atmosphere."
A new set of researches has recently been made known in Poggendorf's Annalen for March, of the present year, which seem to have a further bearing upon the problem of a universal dust. Prof. A. C. Nordenskiöld, of Stockholm, has instituted a series of investigations into the nature of the fine matter entangled and brought to the earth in great snowstorms. After one of these great storms, which occurred on December 1, 1871, he melted a quantity of the newly-fallen snow to ascertain whether it contained any solid particles. A cubic metre was thus tested, and found to contain minute traces of metallic iron and of carbon. He made a second experiment in Finland, in the midst of a large forest, and again particles of carbon and metallic iron were found. Desirous of extending his observations to widely-separated tracts, in 1872 he several times collected snow at localities north of the island of Spitzbergen with the same result—analysis showing the presence of iron, nickel, and cobalt. This dust from the snow greatly resembled a powder previously discovered by him on some islands thirty miles distant from the coast of Greenland, and was probably identical with it. The latter he has called Krykonit, and he was able to collect large quantities of it, and to prove that it contains organic matter, in addition to its other ingredients. It seems highly probable, if not indeed quite certain, that this dust, collected in the snow, is of cosmical origin, and is to be ranked with meteoric matter.
THE OXYGEN CENTENNIAL.
This event went off with great success and satisfaction, according to arrangement, July 31st and August 1st, at Northumberland, Pa., where the great discoverer spent his last days. There
