114 Prof. A. M. Mayer on the History of Young's 



our eye, namely those of different colours. But the number of 

 hues which we can recognize is much smaller than that of the 

 various possible combinations of rays with different wave- 

 lengths which external objects can convey to our eyes. The 

 retina cannot distinguish between the white which is produced 

 by the union of scarlet and bluish-green light, and that which 

 is composed of yellowish green and violet, or of yellow and 

 ultramarine-blue, or of red, green, and violet, or of all the 

 colours of the spectrum united. All these combinations appear 

 identically as white; and yet from a physical point of view they 

 are very different. In fact the only resemblance between the 

 several combinations just mentioned is, that they are indistin- 

 guishable to the human eye. For instance, a surface illumi- 

 nated with red and bluish-green light would come out black in 

 a photograph ; while another lighted with yellowish green and 

 violet would appear very bright, although both surfaces alike 

 seem to the eye to be simply wdiite. 



" Other colours also, especially when they are not 



strongly pronounced, may, like pure white light, be composed 

 of very different mixtures, and yet appear indistinguishable to 

 the eye, while in every other property, physical or chemical, 

 they are entirely distinct. 



" The theory of colours, with all these marvellous and 



complicated relations, was a riddle which Goethe in vain 

 attempted to solve ; nor were we physicists and physiologists 

 more successful. I include myself in the number ; for I long 

 toiled at the task without getting any nearer my object, until 

 I at last discovered 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 and published by the same Thomas Young who first 

 showed the right method of arriving at the interpretation of 

 Egyptian hieroglyphics. He was one of the most acute men 

 who ever lived, but had the misfortune to be too far in advance 

 of his contemporaries. They looked on him with astonishment, 

 but could not follow his bold speculations ; and thus a mass of 

 his most important thoughts remained buried and forgotten in 

 ' The Transactions of the Royal Society,' until a later genera- 

 tion by slow degrees arrived at the rediscovery of his disco- 

 veries, and came to appreciate the force of his argument and 

 the accuracy of his conclusions." 



The first publication by Young of his theory of colour ap- 

 peared in a Bakerian Lecture, entitled " On the Theory of 

 Light and Colours," which Young read before the Royal 

 Society on November 12, 1801. In the opening part of this 

 lecture he says : — " A more extensive examination of Newton's 



