THE 

 LONDON, EDINBURGH and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FOURTH SERIES.] 



DECEMBER 1852. 



\ 



LXIII. Oil Sir David Brewstei-'s New Analysis of Solar Light. 

 By H. Helmholtz*. 



IN a series of papers t published by Sir David Brewster, he 

 has endeavoured to establish a peculiar view which he en- 

 tertains regarding the composition of solar light and the gene- 

 ration of colours." These papers must naturally attract in a high 

 degree the attention of physicists, both on account of the well- 

 won renown of their author in the domain of optical science, 

 and of the new facts which he adduces in support of his asser- 

 tions. According to him, solar light is compounded of three 

 different kinds of light, red, blue and yellow ; and each descrip- 

 tion of light possesses rays of all degrees of refrangibility, but 

 so distributed that red light contains a preponderance of rays of 

 less refrangibility, yellow more rays of mean refrangibility, and 

 blue more of greater refrangibility ; hence it is that the first pre- 

 dominates at the less refrangible end of the spectrum, the second 

 in the middle, and the third at the most refrangible end. The 

 remaining colours of the spectrum, orange, green, violet, are 

 supposed to be caused by the mixture of the three primitive 

 colours. The prism can only separate those rays from each other 

 which possess unequal degrees of refrangibility; if, however, 

 there exist different kinds of light of the same refrangibility, the 



Absorption of the Prismatic Kavs," lu 'Irans. ot the Uoyal soc. oi r.(iiuo. 

 vol. ix. part 2. p. 433. — " On a New Analysis of Solar Light," Ibid, 

 vol'xii. i)artl.p. 123.— "Replv to the Astronomer Royal on the New 

 Analysis of Solar Light," Phil. Mag. i?.3.vol.xxx.p.l53.— " Observations^ou 

 the Analysis of the Spectrum by Absorption," Ibid. vol. xxx. p. 4G1 •—"Re- 

 marks on the Elementary Coloms of the Spectrum," Ibid. vol. xxxii.p.48y. 

 Phil. Mag. S. 4. Vol. 4. No. 27. Dec. 1852. 2 D 



