MEMOIRS OF THE LIFE, WRITINGS AND 



per and patience to his inane objectors, but Sir David flinging bis 

 triple spectrum in tbe face of tbe world with sarcasms 'pen 

 spirituelles,' as Moigno designates tbem, reminds us rather of Ajax 

 defying the lightning. Nor is this all the situation. Newton's 

 hypothesis of emission has been abandoned by every philosopher of 

 eminence except Sir David Brewster, who remains its sole and sturdy 

 defender, but there is this difference between them : Newton's ob- 

 jection to the opposite Huyghenian doctrine was a solid and plausible 

 one, to which no answer, in his day, was or could be given ; he asks 

 and reiterates the question, why, if light were propagated by undula- 

 tions like sound, it should not spread in all directions on passing 

 through an aperture, as sound does, instead of only illuminating the 

 space in front. It required higher analysis than Hooke or Huyghens 

 possessed, to give the real answer to this, but the answer has since 

 been given comoletely, and there is small doubt that if Newton had 

 seen this, he would have discarded his own hypothesis, (as indeed he 

 seems sometimes half inclined to do), in favour of the undulatory. 

 We can willingly excuse Sir David for cutting very short all the cir- 

 cumstances that make in favour of the theory he rejects, but one 

 hardly knows whether most to admire the audacity or feel shame for 

 the infatuation of a sentence like the following, in which, be it 

 observed, the 'disciples of Hooke' are just the whole present genera- 

 tion of philosophers. 



"In the present day, the disciples of Hooke, who 'split pulses ' 

 with more success than he did, and whose theory of light has at- 

 tained a lofty pre-eminence, have not scrupled to imitate their 

 master in measuring optical truths by the undulatory standard, and 

 in questioning and depreciating labours that it cannot explain, or 

 that run counter to its deductions. There is fortunately, however, a 

 small remnant in the Temple of Science, who, while they give to 

 theory its due honours and its proper place, are desirous, as experi- 

 mental philosophers, to follow in the steps of their great master." 



In estimating rightly the grandeur of Newton's discoveries, it is 

 just to consider the circumstances under which they were made : 

 the magnificent temple he erected, marvellous in itself, becomes im- 

 measurably so when we consider that he had not only to build, 

 but to make the bricks, find the straw, and fashion the ladder and 

 trowel. From a Mechanics, for which he had to supply the funda- 

 mental laws — through the planetary and cometary motions — up to the 

 Luuar Perturbations and universal gravitation ; from an Algebra, to 

 which he gave the Binomial Theorem — through the differential and 

 integral calculus which he invented — up to the calculus of Variations 



