M. Fraunhofer on Coloured Spectra. 



Art. II. — Concerning Coloured Spectra ^om Flame, Mocm, 

 ^ and Starlight, and from Electric Light. * By the late M. 

 Le Chevalier Fraunhofer, Member of the Royal Bava- 

 rian Academy of Sciences at Munich. 



It is already known that the coloured spectrum which is pro- 

 duced by means of the prism from the light of a lamp does 

 not show the dark fixed lines which are contained in the spec- 

 trum from sunlight; but instead of it there is in the orange 

 a light line, which is more distinct than the rest of the spec- 

 trum. It is double, and is found at the same place where in 

 the spectrum from sunlight the dark double line D stands. 

 The spectrum which arises from the light of a flame, kept up 

 with a blowpipe, contains several distinct light lines. It is of 

 much greater advantage in optical experiments, that, with a 

 proper blowing of the flame, the light of its anterior half'is not 

 further dissected through the prism, and consequently is 

 simple homogeneous light. This light has, as far as I have 

 hitherto investigated it, the same refrangibility as the ray D 

 from sunlight. Simple homogeneous light going out in all 

 directions is from known reasons very difficult to produce, 

 and never to be obtained directly by prisms ; and hence this 

 flame is of great utility in many experiments. 



By means of the very large electrical machine in the cabinet 

 of natural philosophy of the Royal Academy of Munich, I 

 obtained a spectrum of electric light, in which I recognized a 

 great number of light lines ; and I have determined the relative 

 place of the lightest lines, and the proportions of their inten- 

 sity. The light of the moon has given me a coloured spec- 

 trum, which, in the lighter colours, shows the same fixed lines 

 as the sunlight, and precisely in the same place. 



The light of the moon being too feeble, I could not very 

 distinctly perceive the fixed lines in the darker colours. For 

 the observation of the spectra from the light of the fixed stars, 

 and for the purpose, at the same time, of determining the re- 

 frangibility of their light, I have lately prepared particular 



• This article forms a supplement to the paper of M. Fraunhofer, which 

 we published in our last Number, p. 251. 



