Spectra of some of the Fixed Stars. 417 



Other lines less refrangible were perceived in the spectrum of 

 Jupiter, but were not sufficiently distinct to be measured. The 

 bands in the orange and the red to which we have referred, 

 when examined in the spectrum-apparatus of greater dispersive 

 power, and with a much stronger illumination by directing the 

 apparatus to the sun when near the horizon, are resolved into 

 groups of lines. The stronger of these lines are represented in 

 the upper spectrum of the diagram. The relative position of the 

 band in the red due to lines of oxygen and nitrogen when the 

 induction-spark is taken in air, is shown below the spectrum of 

 Jupiter. This band is in a small degree more refrangible than 

 the strong band due to Jupiter. 



If this band, at 914 of the scale, in Jupiter's spectrum con- 

 sists of lines severally coincident with the lines composing the 

 faint atmospheric band with which it appears to correspond in 

 position, it would seem entitled to be regarded as an evidence of 

 the similarity of Jupiter's atmosphere to our own, with respect 

 at least to one of its constituents, or to one of the vapours diffused 

 through it. The smaller intensity of the bands 882 and 1033 

 would appear to oppose the supposition that Jupiter's atmosphere 

 is identical with our own. This negative evidence, however, 

 cannot be regarded as of much weight, since telescopic observa- 

 tions show that the light which we receive from Jupiter is for 

 the most part reflected from clouds floating in its atmosphere at 

 an elevation above the planetary surface. The solar light, there- 

 fore, would not traverse the lower and denser portions of Jupi- 

 ter's atmosphere, corresponding to those of our own atmosphere 

 in which the vapours, which probably produce these lines, appear 

 to be chiefly present. The band about C, and that a little more 

 refrangible at 838 of the scale, appear quite as strong in Jupiter 

 as in the light from the sky. It may therefore be supposed that 

 these bands are in part due to absorption at Jupiter, since the 

 light from Jupiter suffers less absorption from our atmosphere 

 than does the solar light reflected from the sky under the cir- 

 cumstances in which the observations were made. 



With the exception of these bands in the orange and the red, 

 the spectrum of Jupiter appeared to correspond exactly with that 

 of the sky.— August 31, 1864.] 



Saturn was observed on April 12, 1862, April 14, 1863, and 

 April 12, 1864. Several solar lines were seen, but the spectrum 

 was too faint to permit of any satisfactory determination as to 

 the presence or absence of atmospheric lines. 



[The spectrum of Saturn was observed with the apparatus 

 and in the manner described when speaking of Jupiter, on 

 June 13, 16, and 20, 1864. The spectrum was more difficult of 

 observation, on account of the feebler brilliancy of Saturn, and its 



