CHARACTER OF THE EXPERIMENTALIST. 229 



of treating it, and applied it with a power and success 

 never since equalled. It is wholly a mistake to say that 

 modern science is the result of the Baconian philosophy ; 

 it is the Newtonian philosophy and the Newtonian method 

 which have led to all the great triumphs of physical 

 science, and I repeat that the ' Principia ' forms the true 

 ( Novum Organum.' 



In bringing his theories to a decisive experimental veri- 

 fication, Newton showed, as a general rule, an exquisite 

 skill and ingenuity. In his hands a few simple pieces of 

 apparatus were made to give results involving an unsus- 

 pected depth of meaning. His most beautiful experimental 

 inquiry was that by which he proved the differing refran- 

 gibility of rays of light. To suppose that he originally 

 discovered the power of a prism to break up a beam of 

 white light would be a great mistake, for he speaks of 

 procuring a glass prism to try the celebrated phenomena 

 of colours. But we certainly owe to him the theory that 

 white light is a mixture of rays differing in refran- 

 gibility, and that lights which differ in colour, differ also 

 in refrangibility. Other persons might have conceived 

 this theory ; in fact, any person regarding refraction as a 

 quantitative effect, must see that different parts of the 

 spectrum have suffered different amounts of refraction. 

 But the power of Newton is shown in the tenacity with 

 which he followed his theory into every consequence, 

 and tested each result by a simple but conclusive experi- 

 ment. He first shows that different coloured spots are 

 displaced by different amounts when viewed through a 

 prism, and that their images come to a focus at different 

 distances from the lense, as they should do, if the refran- 

 gibility differed. After excluding by various experiments 

 a variety of indifferent circumstances, he fixes his atten- 

 tion upon the question whether the rays are merely 

 shattered, disturbed, and spread out in a chance manner, 



