594 Transactions of the American Institute. 



the key to the nature of these bodies. The first nebula that he 

 examined, was a comparatively brilliant one in Draco (37 H, iv). 

 The nebulae are usually referred to by letters and numbers which 

 represent the position of these bodies in certain catalogues drawn 

 up by astronomers of eminence. This nebula in Draco, then, 

 instead of giving a continuous spectrum crossed by black lines, like 

 the stars, Wo-s found to give three lines of light only; and the 

 greater part of the light was concentrated in one of these three lines. 

 Indeed, had it not been for this circumstance, the light of the nebula 

 is so excessively faint, that it would have been impossible to see 

 it at all, as spread out in a continuous spectrum, and, in fact, Mr. 

 Huggins scarcely expected it would be possible to get any accurate 

 observation in consequence of the faintness of the light. The 

 result, however, ampl}' rewarded him for his trial. On examining 

 the spectrum of the nebula, and comparing it with those bright 

 lines of the solar spectrum with which it most nearly corresponds, 

 it was found that at the least refrangible end, there was no line cor- 

 responding to the red line of hydrogen. An important obsei-vation 

 made by Plticker, upon rarified gases in tubes, may have a bearing 

 on this point. He found that as hydrogen becomes rarified its red 

 line disappears. Hence, the absence of the red hydrogen line in 

 the nebula may be connected with the attenuated condition of its 

 gaseous materials. It must not be supposed that all the nebulae 

 give lines like the one under consideration. Of sixty which Mr. 

 Huggins has examined, about twenty exhibit the bright lines due to 

 matter in a gaseous state, all of which contain the bright lines cor- 

 responding to that of nitrogen; in some the other fainter lines are 

 not seen. Such spectra are not, therefore, produced by a group 

 of stars; not by a substance like any others that we have seen 

 hitherto in the heavens; they must be furnished by masses of glow- 

 ing gas, which are giving out light of these three particular 

 degrees of refrangibility. 



COPPER FOR CHOLERA. 



Dr. V. Burq, having observed in 1852, that about two hundred 

 persons working in and around a copper foundery, were not attaked 

 by cholera even during the worst stages of the epidemic, made fur- 

 ther inquries and found that all persons handling this metal, whom 

 he met, enjoyed the same immunity. He, therefore, concluded to 

 try the use of copper as a medicine for those attacked by cholera. 

 He administered sulphate of copper internally, and appled metallic 



