480 



SCIENTIFIC THOUGHT. 



11. The beginnings of this line of reasoning are to be 



Dr Young's 



colour found in the writings of Thomas Young, who here, as 



theory. 



in several other directions, " marched far in advance of 

 his age." l During the last decade of the eighteenth 

 century Young had been occupied with the study of 

 the phenomena of Light and Colours ; and, being a 

 student of medicine, he had given equal attention to 

 the physical phenomena and the physiological sensations 

 of Light, going back to the beginnings laid in Newton's 

 writings on these two important branches of Optics. 2 

 I have treated of his epoch-making discoveries in 

 physical optics in an earlier chapter. As to the physi- 

 ological problem of colour sensations, he likewise reviewed 

 Newton's work, and especially took up the remarkable 

 fact noted by Newton, that it appears possible to refer 

 the great variety of colour sensations to three primary 

 elements, out of which the whole wealth of the colour 

 scale varying in intensity, tint, and saturation can 

 be made up. In two distinct points he made a definite 



1 Note, in many passages of 

 Helmholtz's ' Physiologische Optik ' 

 (2nd ed., Braunschweig, 1896), and 

 his often -quoted 'Vortriige und 

 Reden,' the high esteem in which 

 he held the work of Young. 



2 A very succinct and exhaust- 

 ive account of how Young arrived 

 at his colour theory is given in 

 a paper by A. M. Mayer, of New 

 Jersey, in the ' Phil. Magazine ' for 

 1876 (5th series, vol. i. p. 111). 

 Young first selected red, yellow, and 

 blue as the three simple colour- 

 sensations, but later modified his 

 view in consequence of the experi- 

 ments of Wollaston between the 

 years 1802 and 1807. How little 

 Young's theory was thought of may 

 be seen from the words of Helm- 



holtz, quoted by Mayer (p. 114) : 

 " The theory of colour, with all 

 these marvellous and complicated 

 relations, was a riddle which 

 Goethe in vain attempted to solve ; 

 nor were we physicists and physiol- 

 ogists more successful. I include 

 myself in the number ; for I long 

 toiled at the task without getting 

 any nearer my object, until at last 

 I found that a wonderfully simple 

 solution had been discovered at the 

 beginning of this century, and had 

 been in print ever since for any one 

 to read who chose. This solution 

 was found out and published by 

 the same Thomas Young who first 

 showed the right method of arriving 

 at the interpretation of Egyptian 

 hieroglyphics." 



