392 Celestial Chemistry. 



made by Mr. Ross, the cylindrical lens, and some other parts, 

 by Mr. Browning, and the micrometer by Cooke and Sons. In 

 later observations, two other prisms and another small teles- 

 cope, made by Mr. Browning, were nsed, which, with less 

 dispersive power, afforded increased brilliancy, and were occa- 

 sionally very useful. The excellence of the arrangement was 

 shewn by the sharp definition of the lines in the solar and 

 metallic spectra, and by its permitting a line between the 

 double D of the solar spectrum, attributed by Kirchhoff to 

 nickel, to be seen. 



THE MOON AND PLANETS. 



One of the first questions which presented itself to the minds 

 of the observers, was to test the existence or not of an atmos- 

 phere to our satellite, the moon. On all astronomical 

 grounds, the evidence of no appreciable atmosphere is very 

 strong; but there are other points connected with the subject 

 which have a little contrary tendency. It is clear that the 

 sun's light, reflected from the lunar surface, must pass twice 

 through the thickness of any atmosphere the moon may have 

 before reaching us, and judging by the effects of the rays of 

 the sun, when at a low altitude, traversing a length of our own 

 atmosphere, any lines due to its existence should be readily 

 seen. With this view, the spectrum of the moon was carefully 

 examined on many occasions, and while it presented a perfect 

 accordance with the solar spectrum, the lines B, C, the sodium 

 line D, the magnesium group b, F, Gr, and many others of the 

 Frauenhofer lines being seen, nothing could be traced that was 

 indicative of a gaseous envelope about the moon, and the 

 evidence of spectrum analysis may therefore be added to the 

 other reasons for believing that the moon, at any rate on the 

 side presented to our view, has little or no atmosphere. 



The planets, shining equally by light reflected from the 

 sun, exhibit numerous phenomena indicating the existence 

 of atmospheres, of which the varying belts of Jupiter and 

 Saturn, and the diminution of light at the edges of these 

 planets, and Mars andVenus, may be mentioned. The snow and 

 ice of Mars also could only be produced by a gaseous envelope 

 like our own. Still, at first, although the reflective character 

 of the light was proved by the existence of the lines B, C, D, 

 E, b, F, and G, of the solar spectrum in the spectrum of 

 Jupiter, any fresh lines, showing an atmosphere, were not 

 visible until the second pair of prisms, previously mentioned, 

 was used, when the saving of light allowed a line in the red 

 to be seen, and subsequently, by comparing the spectrum of 

 Jupiter with that of the sky at sunset, several other differences 



