MODERN THEORIES OF HEAT AND LIGHT 



these experiments appeared evidently to be inexhaus- 

 tible. 



"It is hardly necessary to add that anything which 

 any insulated body, or system of bodies, can continue 

 to furnish without limitation cannot possibly be a ma- 

 terial substance; and it appears to me to be extremely 

 difficult, if not quite impossible, to form any distinct 

 idea of anything capable of being excited and commu- 

 nicated, in the manner the heat was excited and com- 

 municated in these experiments, except in MOTION." * 



THOMAS YOUNG AND THE WAVE THEORY OF LIGHT 



But contemporary judgment, while it listened re- 

 spectfully to Rumford, was little minded to accept his 

 verdict. The cherished beliefs of a generation are not 

 to be put down with a single blow. Where many minds 

 have a similar drift, however, the first blow may pre- 

 cipitate a general conflict ; and so it was here. Young 

 Humphry Davy had duplicated Rumford 's experi- 

 ments, and reached similar conclusions ; and soon oth- 

 ers fell into line. Then, in 1800, Dr. Thomas Young 

 " Phenomenon Young" they called him at Cambridge, 

 because he was reputed to know everything took up 

 the cudgels for the vibratory theory of light, and it 

 began to be clear that the two "imponderables," heat 

 and li^ r ht, must stand or fall together; but no one as 

 yet made a claim against the fluidity *of electricity. 



Before we take up the details of the assault made by 

 Young upon the old doctrine of the materiality of light, 

 we must pause to consider the personality of Young 

 himself. For it chanced that this Quaker physician 

 was one of those prodigies who come but few times in 



VOL. lit. IJ 2 I ? 



