464 APPENDIX. 



Academy had to apply to the Legislature for authority to depart from 

 the strict letter of the endowment, and use the funds with more freedom 

 in the interest of advancing knowledge. In 1839, the Academy gave 

 from the interest of the fund the sum of $600 to Hare for the invention 

 of the oxyhydrogen blowpipe and improvements in galvanic apparatus. 

 In 1862, it awarded the medal to Ericsson for his caloric engine; in 

 1865, to Treadwell for improvements in the management of heat; in 

 1867, to Alvan Clark for improvements in the lenses of refracting tele- 

 scopes ; in 1870, to Corliss for improvements in steam-engines. The fund 

 had now reached $42,000. It will be seen that the American awards 

 had been mainly for inventions ; the English for discoveries. 



At the six hundred and eighty-ninth meeting of the American Acad- 

 emy, held March 8, 1876, the chairman of the Rumford committee in- 

 troduced the special business of the evening, and handed to the presi- 

 dent, Hon. Charles Francis Adams, the Rumford medals (in gold and 

 silver), on each of which had been engraved the following inscription : 

 " Awarded by the American Academy of Arts and Science to John 

 William Draper for his Researches in Radiant Energy, May 25, 1875." 



In presenting the medals, the president gave a brief history of the 

 fund, and announced that, " after a careful review of the services of Pro- 

 fessor Draper in this great field of inquiry, the committee having the 

 subject in their charge have, for reasons given by them, recommended 

 through their chairman that the medals prescribed in the deed of trust 

 should be presented to him, as having fully deserved them." 



The president then recapitulated some of these reasons : 



"In 1840, Dr. Draper independently discovered the peculiar phenom- 

 ena commonly known as Moser's images, which are formed when a medal 

 or coin is placed upon a polished surface of glass or metal. These im- 

 ages remain, as it were, latent, until a vapor is allowed to condense upon 

 the surface, when the image is developed and becomes visible. 



" At a later period he devised the method of measuring the intensity 

 of the chemical action of light, afterwards perfected and employed by 

 Bunsen and Roscoe in their elaborate investigations. This method con- 

 sists in exposing to the source of light a mixture of equal volumes of 

 chlorine and hydrogen gases. Combination takes place more or less 

 rapidly, and the intensity of the chemical action of the light is measured 

 by the diminution in volume. No other known method compares with 

 this in accuracy, and most valuable results have been obtained by its 

 use. 



"In an elaborate investigation, published in 1847, Dr. Draper estab- 

 lished experimentally the following important facts : 



