488 Intelligence and Miscellaneous Articles. 



between D and D', this being r, 34 towards the red ; but the observa- 

 tion was very difficult, and deserved a careful examination. For this 

 purpose, during two successive evenings the slit was pointed on the 

 line of maximum obscurity in the terrestrial atmospheric band, and 

 it was found to be in the exact prolongation of that of sodium. 

 The micrometer was left untouched until Jupiter appeared. It was 

 observed that the darkest band of Jupiter was outside the slit and 

 the ray D by its own size ; so that even the maximum of this band 

 does not coincide with that of the terrestrial atmosphere. If the 

 bands y and jo are referred to those of sodium, we find 



D-y = 2-26, D-/3 = 4-ll. 



These numbers agree with those of our atmosphere no better than 

 the preceding. The band (3 is not far removed from B ; and it might 

 be said that the difficulty of the measurement would allow for the 

 difference ; but it exceeds the probable error of the measurements. 

 The ray C and its terrestrial atmospheric band are quite wanting in 

 Jupiter; and, on the other hand, y, which is greatly developed, sug- 

 gests C 6 more than C. I may say that C 6 is very developed in our 

 atmosphere on foggy days. 



These results were confirmed, as far as it was possible to rely 

 upon them, by the observations and the figures published last year 

 in the ' Memoirs ' of the Observatory, where it might be seen that 

 the system of Jupiter's bands on the red parts differ from the terres- 

 trial band. 



Besides these rays and several others, Jupiter at first sight shows 

 another band c outside D towards the blue, which is analogous to 

 the d of Brewster, and it would be necessary to proceed to further 

 measurements even for this. But I would not delay the communi- 

 cation of these results to you before the planet is too near the hori- 

 zon, in order that these results, which are the most striking, may be 

 confirmed by those who possess powerful instruments. 



Before finishing, I may reply to a possible objection : If the posi- 

 tion of these lines is correct, the solar rays will not be visible upon 

 Jupiter, which does not agree with received ideas. I answer that 

 this does not necessarily follow from my measurements ; the solar 

 rays may in fact exist ; but being very much spread out and very 

 fine, they would be confounded with the penumbra of these bands 

 themselves ; for in fact the position of the solar rays falls so nearly 

 in the neighbourhood of the bands, that for want of light in the 

 planet it would be difficult to see them without a more powerful 

 instrument. In fact, if the moon is viewed with a small diaphragm 

 in front of the object-glass, so as to reduce the light of the spectrum 

 almost as much as has been done for Jupiter, the red rays can only 

 be distinguished with extreme difficulty. I think, therefore, that 

 these observations do not disprove the existence of solar rays in the 

 planet, but show that its atmosphere has a strong absorbing pow r er, 

 and a different one from ours. — Comptes Rendus, August 17, 1864. 



