MODERN THEORIES OF HEAT AND LIGHT 



don to follow out the humdrum life of a practitioner of 

 medicine in the year 1801 . But incidentally the young 

 physician was prevailed upon to occupy the interims 

 of early practice by fulfilling the duties of the chair of 

 Natural Philosophy at the Royal Institution, which 

 Count Rumford had founded, and of which Davy was 

 then Professor of Chemistry the institution whose 

 glories have been perpetuated by such names as Fara- 

 day and Tyndall, and which the Briton of to-day 

 speaks of as the " Pantheon of Science." Here it was 

 that Thomas Young made those studies which have 

 insured him a niche in the temple of fame not far re- 

 moved from that of Isaac Newton. 



As early as 1793, when he was only twenty, Young 

 had begun to communicate papers to the Royal Society 

 of London, which were adjudged worthy to be printed 

 in full in the Philosophical Transactions; so it is not 

 strange that he should have been asked to deliver the 

 Bakerian lecture before that learned body the very first 

 year after he came to London. The lecture was de- 

 livered November 12, 1801. Its subject was "The 

 Theory of Light and Colors," and its reading marks 

 an epoch in physical science ; for here was brought for- 

 ward for the first time convincing proof of that undu- 

 latory theory of light with which every student of 

 modern physics is familiar the theory which holds 

 that light is not a corporeal entity, but a mere pulsa- 

 tion in the substance of an all-pervading ether, just as 

 sound is a pulsation in the air, or in liquids or solids, 

 mg had, indeed, advocated this theory at an 

 earlier date, but it was not until 1801 that he hit upon 

 the idea which enabled him to bring it to anything ap- 



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