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On a New Analysis of Solar Light, indicating three Primary 

 Colours, forming Coincident Spectra of equal length. By DAVID 

 BREWSTEP, LL.D. F.R.SS. Lond. & Ed. 



(Read 21st March 1831.) 



_L HE decomposition of white light by prismatic refraction, as ef- 

 fected by SIR ISAAC NEWTON, has, for more than a hundred and 

 fifty years, been received as a demonstrated truth by the most 

 distinguished philosophers of all nations. Various attempts in- 

 deed have been made, both in his day and in ours, to over- 

 turn this beautiful generalization, but they have been made by 

 persons not only ignorant of the subject, but unacquainted with 

 the first principles of physical research. 



The analysis of light by the prism is perfect, in so far as it 

 goes, and was demonstrated by NEWTON in the case of spectra 

 produced by the single refracting medium which he employed. 

 It was left, indeed, to his successors to discover the diiferent dis- 

 persive powers of bodies, and the irrationality of the coloured 

 spaces, and thus to establish the principles of the Achromatic 

 and the Aplanatic Telescopes. These discoveries presented no 

 points of objection to the views of NEWTON. They were entirely 

 of a supplementary character, and were calculated to establish 

 more firmly his general doctrine respecting the composition of 

 light. 



In submitting to the scientific world a new analysis of light, 

 I am fully aware of the difficulties which I have to encounter. 



