418 Mr. W. Huargiiis and Dr. W. A. Miller on the 



l OO 



less favourable position. Bands in the red and orange were seen 

 similar to those in the spectrum of Jupiter, and by measurement 

 these bands were found to occupy positions in the spectrum cor- 

 responding to those of the bands of Jupiter. — August 31,1864.]* 



The spectrum of Mars was observed on November 6, 1862, 

 and April 17, 1863. The principal solar lines were seen, and 

 no other strong lines were noticed. 



[On August 10 and 29, 1864, we re-examined Mars, using 

 the new spectrum-apparatus. No lines in the red, similar to 

 those of Jupiter and Saturn, were observed ; but in the extreme 

 red, probably about B and a, two or three strong lines were seen. 

 With the exception of these, no lines were detected in the red, 

 orange, yellow, and green portions of the spectrum, other than 

 those of the solar spectrum. At about F the brilliancy of the 

 spectrum diminishes in a remarkable manner, in consequence of 

 a series of strong and nearly equidistant bands, which com- 

 mences at F and continues towards the more refrangible end as 

 far as the spectrum can be traced. The absorption of these 

 bands is evidently the cause of the predominance of the red rays 

 in the light of this planet. 



The spectrum-apparatus of greater power resolves these bands 

 in the blue into groups of lines. — August 31, 1864.] 



The light of Venus gives a spectrum of great beauty. The 

 observations were chiefly made on April 17, 22, and 26, 1863. 

 The line D was seen double. B, C, and numerous solar lines to 

 a little distance beyond G, were distinctly visible ; and the prin- 

 cipal of these were measured and found to agree with correspond- 

 ing lines in the solar spectrum. Lines other than these, and in 

 the position in which the stronger atmospheric lines present 

 themselves, were carefully looked for, but no satisfactory evidence 

 of any such lines has been obtained. Venus was observed as 

 early in the evening as possible, and while a considerable amount 

 of daylight still remained. 



The imperfect evidence which analysis by the prism affords of 

 the existence of atmospheres around these planets, notwithstand- 

 ing the high probability, amounting almost to certainly in the 

 case of Jupiter, that such atmospheres do exist, may receive an 

 explanation in the supposition that the light is chiefly reflected, 

 not from the planetary surfaces, but from masses of cloud in the 

 upper strata of their atmospheres. In this case the length of 



* [The authors reobserved Saturn on June 13, 1865. They found the 

 spectra of the ansse of the rings to be brighter than that of the ball. The 

 dark lines in the red and orange, however, were less distinct in the light of 

 the rings than in that of the ball. This observation is in accordance with 

 the telescopic appearance of Saturn and his rings when viewed with high 

 powers.] 



