"RITTI RS DARK RAYS" 159 



prove. He could and did show that a thermometer 

 rose in passing from the \ the red end of the 



spec 1 1 !. -ii-l in..!-.- lie placed the ther- 



mometer boy on. 1 le red, nn<i funl that, aa it 



<, hcat-rayH, in\isil,l,- t., the eye *nd It 

 less bent from the straight path of the sunbeam, gave ]j 



tin- jjivat.-st h-;it Hi- inu-t h:iv- a-K- i hiiM-!l" Is 



there not something similar at a he 



had not the means of answering the quest i< n, if 

 what was next best He asked a question pregnant 



the welfare and instruction of man 

 may be pardonable if I digress for a moment, and 

 that the foregoing researches ought to lead us 

 on to others. May not the chemical properties of the 

 ic colours be as different as those which relate 

 >t ind heat: . . they may reside only in one of 

 colours." To this question he could neither gi 

 get an answer. A short time passed, and the 

 answer came from Germany and, independently, from 

 Jand. " The existence of solar rays accompanying 

 more refrangible than the violet rays, and 

 cognisable by chemical effects, was first 



ascertained by Mr. Hitter." They were called "The 

 k rays < > ' and " appeared to extend beyond 



phe violet rays of the prismatic Hpi-ctriim. through a 

 space nearly equal to that which is occupied by t 

 let" "Paper dipped in a solution of nitrate of 

 was used to prove the existence of these 

 il rays and to introduce the days of photo- 

 graphy. It was most fitting that it should be so. 

 astronomer led the way in this new quest after 

 invisible rays; chemistry supplemented his discoveries 



