236 ANNUAL OF SCIENTIFIC DISCOVERY. 



^^ Jupiter. — In the spectrum of Jupiter, lines are seen, which 

 indicate tlie existence of an absorptive atmosphere al)out this 

 ])lanct. In tiiis diaijram these lines are presented as they ap- 

 peared when viewed simultaneously with the spectrum of the sky, 

 which, at the time of observation, rellected the light of the setting 

 sun. One strong band corresponds with some terrestrial atmos- 

 pheric lines, and prol)ably indicates the presence of vapors similar 

 to tiiose which are about tlie earth. Another band has no counter- 

 part amongst the lines of absorption of our atmosphere, and tells 

 us of some gas or vajjor which does not exist in the earth's atmos- 

 phere. 



" Saturn. — The spectrum of Saturn is feeble, but lines similar 

 to those which distinguish the spectrum of Ju2)it(U' were detected. 

 These lines are less strongly marlccd in the ansje of the rings, 

 and show tiiat the al)sorptive powt-r of the atmosphere al)()ut the 

 rings is less than that of tiie atmosphere wliiuh surrounds the 

 ball. A distinguished foreigner, i>resent at the meeting, Janssen, 

 has quite recentl}' found tliat several of tlie atmospheric lines in 

 this part of the spcctriun are produced by aqueous vapor. It 

 appears to be very probable that Aqueous vapor exists in the 

 atmospheres of Jupiter anil Saturn. 



*^ Mars. — On one occasion some remarkable groups of lines 

 were seen in the more refrangible part of the spectrum of Mars. 

 These may be connected with the source of the red color which 

 distinguishes this planet. 



" Vows. — Though the spectrum of Venus is brilliant, and the 

 lines of Fraunhofer were well seen, no additional lines affording 

 evidence of an atmosphere about Venus were detected. The 

 abseni'e of lines may be due to the circumstance that the light is 

 probably reflected, not from the planetary surface, but from clouds 

 at some elevation above it. The light which reaches us in this 

 way, by reflexion from clouds, would not have been exi^oscd to 

 the absorbent action of the lower and denser strata of the planet's 

 atmosphere. 



" The Fixed Stars. — The fixed stars, though immensely more 

 remote, and less conspicuous in brightness than the moon and 

 planets, j'et because they are original sources of light, furnish us 

 with fuller indications of their nature. 



" The stars have indeed been represented as suns, each uphold- 

 ing a dependent family of jjlanets. This opinion rested upon a 

 possible analogy alone. It was not more than a si^eculation. 

 We possessed no certain knowledge from observation of the true 

 nature of those remote points of light. This long and earnestly- 

 coveted information is at last furnished by spectrum analysis. 

 We are now able to read in the light of each star some indications 

 of its nature. I will take first the spectra of two bright stars 

 which we have examined with great care. 



"The upper one represents the spectrum of Aldebaran, and 

 the other that of Betelgeux, the star marked a in the constella- 

 tion of Orion. 



" The positions of all these dark lines, about eighty in each star, 

 were determined by careful and repeated measures. These 



