A HISTORY OF SCIENCE 



ments by which this composition is demonstrated be- 

 come familiar to every one. The experiments were 

 absolutely novel when Newton brought them forward, 

 and his demonstration of the composition of light was 

 one of the most striking expositions ever brought to 

 the attention of the Royal Society. It is hardly nec- 

 essary to add that, notwithstanding the conclusive 

 character of Newton's work, his explanations did not 

 for a long time meet with general acceptance. 



Newton was led to his discovery by some experiments 

 made with an ordinary glass prism applied to a hole 

 in the shutter of a darkened room, the refracted rays 

 of the sunlight being received upon the opposite wall 

 and forming there the familiar spectrum. " It was a 

 very pleasing diversion," he wrote, " to view the vivid 

 and intense colors produced thereby ; and after a time, 

 applying myself to consider them very circumspectly, 

 I became surprised to see them in varying form, which, 

 according to the received laws of refraction, I expected 

 should have been circular. They were terminated 

 at the sides with straight lines, but at the ends the 

 decay of light was so gradual that it was difficult to 

 determine justly what was their figure, yet they seemed 

 semicircular. 



''Comparing the length of this colored spectrum 

 with its breadth, I found it almost five times greater; 

 a disproportion so extravagant that it excited me to a 

 more than ordinary curiosity of examining from whence 

 it might proceed. I could scarce think that the vari- 

 ous thicknesses of the glass, or the termination with 

 shadow or darkness, could have any influence on light 

 to produce such an effect ; yet I thought it not amiss, 



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