ASTRONOMY AND METEOIlOLOCr. 343 



proaching to red. These results are interesting as bearing on the 

 apparent identity of the orbits of the periodical meteors with those 

 of some comets. — Chemical News. 



FACTS IN spectrum: analysis. 



Spectra of the Stars. — The proper motion of the stars, or their 

 apparent change of place, is in reality only the transverse portion 

 of their true motion ; the other part, or the motion of the star di- 

 rectly to or from the eye, produces no effects perceptible to the 

 telescope. It would require thousands of years before any motion 

 of this sort could produce an appreciable change in a star's appar- 

 ent brilliancy. By means of spectroscopic analysis Mr. Huggins 

 hafe led the way in a process of research which promises to afford 

 us information respecting this part of the stellar motions. The 

 law on which the inquiry proceeds may be thus illustrated : If a 

 powerful swimmer urge his way rapidly against a series of ad- 

 vancing waves, it is evident that they will pass him more rapidly 

 — in other words, they will seem narrower — than if he were at 

 rest ; on the contrary, if he urged his way in the same direction 

 as the waves, they would appear broader than they really are. As 

 the light of the stars reaches us in a succession of minute waves, 

 it is clear that if we are approaching a star or receding from it, 

 whether through the eai-th's motion or that of the star, the light- 

 waves will appear modified in length, — in other words, the light's 

 refrangibility will be altered. Thus the lines in the star's spectrum 

 ■will be altered in position, and will no longer coincide with the 

 corresponding lines in the spectra of terrestrial substances. Mr. 

 HusfSfius' delicate researches have shown, first, that the nebulaa 

 are not approaching the earth nor receding from it at a rate which 

 is appreciable by his instruments; second, that the bright star 

 Sirius — the only fixed star which he has had time to examine 

 satisfactorily — is approaching the solar system at the rate of 

 nearly 29^ miles per second. — Quart. Jour, of Science, July, 1868. 



Spectra of the Nebulce. — Mr. Huggins finds that when the in- 

 tensity of the spectrum of nitrogen is diminished by removing the 

 induction spark in nitrogen to a sufficient distance, the whole 

 spectrum disappears except the double line, which agrees in posi- 

 tion with the bright line in the nebulae. " It is obvious," he says, 

 " that if the spectrum of hydrogen were greatly reduced in inten- 

 sity, the strong line in the blue, which corresponds to one of the 

 lines of the nebular spectrum, would remain visible after the line 

 in the red, and the lines more refrangible than F, had become too 

 feeble to affect the eye." There seems reason for supposing that the 

 light of the gaseous nebulae is emitted by nitrogen and hydrogen. 



Spectra of the Umbrce and Penumbrce of Solar Spots. — According 

 to Messrs. Lockj-er and Huggins, most of the dark lines of the 

 solar spectrum are wider in the spectrum of the umbrae. The 

 lines F and C, due to hydrogen, are not stronger ; none of the lines 

 of the normal solar spectrum were wanting in the spectrum of the 

 umbra. 



