628 



THE POPULAR SCIENCE MONTHLY, 



to the conclusion that there is such a 

 tiling as a cosmical dust, and that this 

 form of matter, subtile as it may be, is 

 by no means without effect in the oper- 

 ations of the universal scheme. The 

 inconceivably rapid growth of the tails 

 of comets directed away from the sun, 

 and the mighty sweep of their move- 

 ments, seem inconsistent with the 

 direct flight or passage of cometary 

 particles, and the effect is now rather 

 explained on the hypothesis that mat- 

 ter already existing, diffused through 

 space, may become in some way elec- 

 trically polarized and rendered lumin- 

 ous thi'ough the mutual action of the 

 sun and the comet. A recent writer 

 suggests that "these polarized par- 

 ticles, 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 appar- 

 ent spread of the tail." The earth is 

 believed to have passed through a por- 

 tion 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 pos- 

 sible that, on the evening of June 30th, 

 the earth might have been involved in 

 the tail, wliile certain unusual phenom- 

 ena of an electrical nature were actu- 

 ally observed at that time. The writer 

 on "Comets," in Brande's "Cyclope- 

 dia," says : 



"It is a remarkable and significant fact 

 that, not only in various parts of England 

 and Ireland, but also in Spain, Italy, Switzer- 

 land, 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 re- 

 semble the usual effect of the aurora, but 

 was something quite exceptional. We in- 

 cline to attribute the phenomenon to the 



I presence of cometic matter (if matter it can 

 be termed) in our atmosphere." 



A new set of researches has recent- 

 ly been made known in Poggendorfs 

 Annalen for March, of the present 

 year, which seem to have a further 

 bearing upon the problem of a uni- 

 versal dust. Prof. A. C. Nordens- 

 kiold, of Stockholm, has instituted a 

 series of investigations into the na- 

 ture of the fine matter entangled and 

 brought to the earth in great snow- 

 storms. After one of these great 

 storms, w^hich occurred on December 

 1, 1871, he melted a quantity of the 

 newly-fallen snow to ascertain whether 

 it contained any solid particles. A cu- 

 bic metre was thus tested, and found 

 to contain minute traces of metallic 

 iron and of carbon. He made a sec- 

 ond experiment in Finland, in the 

 midst of a large forest, and again par- 

 ticles of carbon and metallic iron were 

 found. Desirous of extending his ob- 

 servations to widely-separated tracts, 

 in 1872 he several times collected snow 

 at localities north of the island of Spitz- 

 bergen 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 thir- 

 ty miles distant from the coast of Green- 

 land, and was probably identical with 

 it. The latter he has called Erylconit^ 

 and he was able to collect large quan- 

 tities of it, and to prove that it con- 

 tains 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. 



TEE OXYOEJSr CENTENNIAL. 



This event went off with great suc- 

 cess and satisfaction, according to ar- 

 rangement, July 31st and August 1st, at 

 Northumberland, Pa., where the great 

 discoverer spent his last days. There 



