[58] At the Anniversary of the Royal Society, November 1796, Count Rumford transferred one thousand pounds, Three per Cent. Consols, to the use of the Society, on condition that a premium should be biennially awarded to the author of the most important discovery, or useful invention, made known in any part of Europe during the preceding two years, on the subject of HEAT AND LIGHT. In regard to the form in which this premium was to be conferred, he requested that it might always be given in two medals, struck in the same die, the one of gold, and the other of silver. Should not any discovery or improvement be made during any terms of years, he directed that the value of the medals should be reserved, and being laid out in the purchase of additional stock, go in augmentation of the capital of this premium. Medals upon this foundation have been successively voted to Professor Leslie, for his Experiments on Heat, published in his work entitled "An Experimental Enquiry into the Nature and Properties of Heat;"--To Mr. William Murdoch, for his publication "On the Employment of Gas and Coal for the purpose of Illumination;"--to M. Malus, for his discoveries of certain new properties of reflected light;--to Dr. Wells, for his Essay on Dew;--to Sir Humphry Davy, as above stated;--to Dr. Brewster, for his Optical Investigations;--and, lastly, to Mr. Fresnel, for his optical researches. On the completion of these laborious enquiries, it was thought expedient to give a wider circulation to their results than the publication of them in the Philosophical Transactions was calculated to afford; and Sir Humphry Davy was therefore induced to reprint his principal memoirs, so as to form an octavo volume,[59] which might be accessible to the practical parts of the community. [59] "On the Safety-lamp for Coal Mines, with some Researches on Flame.--London, 1818."