Eucke's Comet

This littlo cornet, ttfe neaerost to the sun " in average diatance, and consoqv.ently the most frequent in its periodioal j anees of all that have peen observed by astronomors, has been on hand again, ] Prof. Young, of Dartmouth, writes in the Boston JoUrnal of Cfiemütry, that its diameter is bet ween 40,000 and 50,000 miles, that he saw it on December lfeVpass centrally over a little star of the ninth magnitude, the brightness of which was not apparently dimmed in the least, showinjr, like other similar observations, that the siibstanco of cometa i inconceivably rare. The gpectroscope shows it to be gaseous. ■ and probably gaseous only. The speotrum i julicates carbon. Like moet of tho , smaller cometa, it carries its tail beforo it , in approaching the sun. The doctrine of a resisting medium, fllling the interplanetary spaces, was doduced by Encke with ïnuch laborious lation and sble reauoning, from the i served gradual shortening of the poriods i of this cornet, which he averred could not be accountod for by any known action of the planets. The frequency of its returns, which occur in a little less thivn three years and four inonths, makes the phenomenon of retardation comparativo ly easy to determine ; but the most modern and most accurate observations do not seom to have been discussed with reference to this point. Professor Young says the other cometa show nothing similar as yet, and that the whole question needs investigation. Jleanwhile tho hypothesis of an interplanetary medium is very convenient to the physical materialista who abhor a vacuüm more than nature ever did, and who begin to demand an ether for the transmission of heat, gravitation, and all forma of force, as woll as for light, while at the same time they aro naturally roluctant to endow this assumcd medium with new qualities, or to take from it any of the univeraally observed attributes of matter. Tho imponderable ether, like the invisible atom, is philosophically troublesome, though practically and temporarily convenient.