362 THE POPULAR SCIENCE MONTHLY. 



medicine. It is adorned with many great inventions, such as photog- 

 raphy, the electric telegraph, the construction of railways, and ocean 

 steam navigation. The great wars it has witnessed, the Franco-Ital- 

 ian, the Crimean, the Prusso-Austrian, the Prusso-French, and the 

 American Civil War, have occasioned, as all great wars inevitably do, 

 much intellectual activity and profound social changes. Among the 

 latter are the emancipation of the vast serf population of Russia, and 

 of four million slaves in America. But, perhaps, most important 

 of all — partly through the increase and diffusion of knowledge, partly 

 through more rapid and incessant national intercommunication — ideas 

 liberal in politics and elevated in religion have asserted their sway. 



The generation that lived in this period has therefore fairly per- 

 formed its share in the promotion of modern civilization. There is 

 no European nation which has not participated in this great move- 

 ment — none that cannot offer a list of the names of its people who 

 may lay claim to a part of the honor of the success. In this respect 

 America is not behind others — she too has done her share, both as 

 regards science and industrial inventions. Among those of her citizens 

 who have devoted their lives to these objects, and who by their suc- 

 cessful pursuit have done honor to the country, and won for them- 

 selves an eminent name in the world of science, is the subject of our 

 present sketch, John William Draper. 



He was born at St. Helen's, near Liverpool, in 1811, and received 

 his education for the most part from private instructors. At eleven 

 years of age he was sent to one of the public schools of the Wesleyan 

 Methodists, of which denomination his father was a minister. He re- 

 mained there, however, only two years, and was then returned to pri- 

 vate instruction. When the University of London was opened, he 

 was sent there to study chemistry under Dr. Turner, at that time the 

 most celebrated of English chemists. At the instance of several of 

 his American relatives, he came to America, and completed his medi- 

 cal education at the University of Pennsylvania, graduating in 1836 

 with so much distinction that his inaugural thesis received the unu- 

 sual compliment of being published by the faculty of that university. 

 Shortly afterward he was appointed Professor of Chemistry in Hamp- 

 den Sidney College, Virginia, and in 1839 received an appointment to 

 the same professorship in the University of New York, with which 

 institution he has ever since been connected. 



Dr. Draper's earliest scientific publications were on the chemical 

 action of light, a subject at that time almost completely neglected. 

 Eventually he published in American and foreign journals, or read 

 before scientific societies, nearly forty memoirs in relation to it. It 

 would be impossible in this short sketch to give an enumeration of 

 the facts contained in these papers. We shall, therefore, select only a 

 few of the more prominent ones for remark. 



Of all the chemical actions of light, by far the most important 



