gRCT . ,„.j DISSERTATION SECOND. 83 



but denied that the cause of the colour is in any quality 

 residing permanently in the rays of light, any more than 

 that the sounds emitted from the pipes of an organ exist 

 originally in the air. An imaginary analogy between sound 

 and light seems to have been the basis of all his optical theo- 

 ries. He conceived that colour is nothing but the disturbance 

 of light by pulses propagated through it; that blackness 

 proceeds from the scarcity, whiteness from the plenty, of 

 undisturbed light; and that the prism acts by exciting 

 different pulses in this fluid, which pulses give rise to the 

 sensations of colour. This obscure and unintelligible theo- 

 ry (if we may honour what is unintelligible with the 

 name of a theory) he accompanied with a multitude of 

 captious objections to the reasonings of Newton, whom 

 he was not ashamed to charge with borrowing from him 

 without acknowledgment. To all this Newton replied, 

 with the solidity, calmness, and modesty, which became the 

 understanding and the temper of a true philosopher. 



The new theory of colours was quickly assailed by 

 several other writers, who seem all to have had a better 

 apology than Hooke for the errors into which they fell. 

 Among them one of the tirst was Father Pardies, who 

 wrote against the experiments, and what he was pleased 

 to call the hypothesis, of Newton. A satisfactory and 

 calm reply convinced him of his mistake, which he had 

 the candour very readily to acknowledge. A countryman 

 of his, Mariotte, was more difficult ta be reconciled, and, 

 though very conversant with experiment, appears never 

 to have succeeded in repeating the experiments of New- 

 ton. Desaguliers, ut the request of the latter, repeated 

 the experiments doubted of before the Royal Society, 

 w r here Monmort, a countryman and a friend of Mariotte. 

 was present. 1 



1 Montucla, Toru. II. 



