76 Intelligence and Miscellaneous Articles, 



first that we are justified in concluding the light to be formed solely 

 of reflected solar light ; now that which comes from the sun would 

 perhaps only constitute the diffused basis of the field of vision. 

 The comet would then have a light of its own, the tint of which 

 very much resembles that of the nebulas, but its position greatly 

 differs from that of the nebular lines, one of which coincides with/. 

 The other line of the comet is also different in position, and is on 

 the further side, nearer magnesium than the nebular ray. It is thus 

 proved that the displacement does not result from motion, but 

 is due to the nature of the cometary matter. As these bands are 

 more luminous than those of a star of equal magnitude, we are led to 

 the assumption of a special light emanating from the comet. The 

 measurements are not close enough to justify our comparing these 

 spectra with those of other known spectra ; and we now know, more- 

 over, that this comparison would be illusory, for the visibility of the 

 spectra in gases depends on numerous circumstances which we can- 

 not determine. 



In the second place, this spectrum strongly resembles that which 

 other astronomers besides myself have observed in other comets. 

 We may thus generalize these results by induction ; and that 

 would furnish an argument for the extraplanetary origin of these 

 bodies. 



Taking Venus near its greatest digression, and analyzing it with a 

 spectroscope with angular vision with two prisms, I observed that the 

 light indicated traces of atmospheric action at a height above the 

 horizon too great for the influence of the terrestrial atmosphere to 

 be perceptible. This must then be referred to the atmosphere of 

 Venus itself. It is well seen in the region of Brewster, named d, and 

 in the other region in front of the sodium. These bands are due to 

 aqueous vapour. The lines of nitrogen of the air near F are also 

 greatly strengthened, which proves the presence of an atmosphere 

 about this planet analogous to our own. 



These observations have been confirmed on the simple spectro- 

 scope made with Merz's and with Hofmann's prisms, using eyepieces 

 formed with cylindrical lenses, which were sent me by M. Merz, and 

 which possess a high degree of perfection. 



Now that with such powerful means we can penetrate into the 

 constitution of the stars, I have put the question to myself whether 

 the diversity of the spectra in certain types of stars does not rather 

 arise from differences in the proportions of substances which consti- 

 tute them, than from an absolute diversity in the substances them- 

 selves. I have commenced this investigation in detail by comparing 

 stars of the second type (yellow stars like our sun) and red stars of 

 the third type. 



Comparing the two stars a Orionis and Arcturus, a surprising 

 identity is found between the principal lines and those of our sun. 

 More than thirty lines were found to be identical with those of 

 Fraunhofer's map, which by its size is better fitted for these com- 

 parisons than Kirchhoff's large map. The fundamental difference 

 appeared to consist in the strongest lines being more intense in 



