20 THE CHEMISTRY OF THE SUN. [CHAP. 



fainter than that of Venus, the brightness of their spectra was 

 consequently still less. I have nevertheless seen, without any 

 illusion in the spectrum of the light of Sirius, three large lines, 

 which apparently have no resemblance with those of the sun's 

 light. One of them is in the green, and two in the blue, space. 

 Lines are also seen in the spectrum of other fixed stars of the first 

 magnitude." * 



No wonder that a man who had thus brought sun, planet, 

 and star within the grip of a new instrument should not rest 

 content with these observations. 



He next investigated at considerable length the spectra of 

 artificial light sources. In an early part of his paper 2 he 

 states that, on examining the spectra of artificial flames, he 

 found that flames such as that of a lamp or candle, and, 

 indeed, 



"In general, the light produced by the flame of a fire, exhibit 

 between the red and yellow of the spectrum a clear and well-marked 

 line, which occupies the same place in all the spectra. This line 

 will become more important in the sequel, and it was one of great 

 utility to me. It appears to be formed by rays which are not 

 decomposed by the prism, and which consequently are homogeneous. 

 In the green space we perceive a similar line, but it is weaker and 

 less distinct, so that it is often very difficult to find." 



Eeturning to this subject later on he notes 3 that in trans- 

 mitting the light of a lamp through the same aperture employed 

 for the examination of the solar spectrum, he observed a line 

 corresponding exactly in position with the D line in the solar 

 spectrum ; nay, both the lines were double ! 



" In making the light of a lamp fall through a narrow aperture, 

 from 15" to 30" wide, upon a prism of great dispersion, placed 

 before the telescope, we perceive that the red line of this spectrum 



1 Edin. Phil. Journal, vol. x. pp. 38, 39. 2 Ibid. vol. ix. p. 291. 



3 Ibid. p. 2ft 8. 



