106 ANNUAL OF SCIENTIFIC DISCOVERY. 



An important step in the analysis of light was made by Sir David 

 Brewster when he showed that, by looking at the spectrum through 

 absorbing media of different colors, it is seen to consist neither of 

 seven colors as Newton believed, nor of four as Wollaston alleged, 

 but of three spectra red, yellow, and blue, which have equal lengths 

 but varying intensities, superposed on one another. Beyond this con- 

 clusion, however, Brewster did not go ; and he certainly does not 

 hazard an estimate of the quantify of red, yellow, and blue rays present 

 in solar light. It is true that in accounting for the presence of the 

 white light which becomes visible at any point of the spectrum when a 

 sufficient amount of the colored light at that point has been absorbed, 

 he conjectures that there is a combination of some definite proportion 

 of red, yellow, and blue rays which forms the white light. He .conjec- 

 tures, for example, that if we admit the intensity of white light to be 

 10, this intensity may result from the combination of three rays of red, 

 five yellow, and two of blue. These numbers are given, be it observed, 

 merely by way of example ; and the great master of experimental 

 optics who gives them is too profoundly versed in his science to im- 

 agine for a moment that he has attained such knowledge of light as 

 to express in numbers the amount of its constituent elements. The 

 preceding hypothesis was given upwards of thirty years ago in more 

 than one article on the New Analysis of Light, and that "the author 

 has not changed his views in the interim is proved by his employing, 

 in the last edition of the Encyclopaedia Britannica, precisely the same 

 words in elucidating the subject. 



A consideration of the difterence in the views of Newton, Wollaston, 

 and Brewster ought to convince every one of the extreme difficulty 

 to say the very least of it of determining the amount of colored rays 

 which compose the sunbeam. Mr. Field offers a solution of the 

 question that professes an accuracy to which no one of the three now 

 given lays any claim. His analysis so far agrees with that of Brewster 

 as to give red, yellow, and blue as the constituents of light, but it 

 differs from it inasmuch as it assigns definite numerical proportions to 

 these colors. White light, Mr. Field says, is composed of red, yellow 

 and blue colors, in the proportion of five, three, and eight respectively. 

 This, it will be seen, differs wholly from the hypothesis of Brewster, in 

 which is assigned a proportion of three, five, and two to the same rays. 



Mr. Field's analysis of light does not appear to have found favor 

 with scientists, but the practical art of ornamental coloring has very 

 generally been inclined to adopt it. Thus Mr. Owen Jones, in his 

 Grammar of Ornament, states his first law of importance, as follows, 

 " The primary colors of equal intensities will harmonize with or neutral- 

 ize each other in the proportion of three yellow, five red, and eight blue," 

 etc. The same law is also given in the short handbook on Harmony of 

 Color issued at the Kensington School of Art, apparently with the 

 sanction of government, and widely circulated among the art-stu- 

 dents of the Kingdom. London Athenaeum. 



CURIOUS SPECULATIONS ON THE NATURE OF LIGHT. 



The following curious speculations on the nature of light are put 

 forth by Mr. B, S. Barnard, in the London Photograph News : 

 " ' As white as fine linen,' ' as white as snow,' are frequent compari- 



