MAYER, Juuus ROBERT, Dr., a German physicist, b. in Heilbronn, Wrirtemberg, 1814. He att,ended the g,ymnasium at Heilbronn, studied medicine at Tubingen, and finished his course at Munich and Paris. He made a voyage to Java in 1840, and while there he made observations on the blood which led him to the investigation of the sub ject of animal heat, and finally to that of the conservation and correlation of forces. After his return to Heilbronn he became town physician, which interrupted his invea tigations, but he published a preliminary notice of the work he had accomplished. up to 184;?,, in Liebig's Annalen der Chemie und Phcormaoie under the title Bemerkungeil fiber die Krafte der unbelebten, Hatur. In 1845, he made a fuller explanation of the subject in a memoir, under the title,..Die organieche Bewegung in arena Znisammenhange mit dem Stoff wechsel. In 1848 he published Beitrage zur Dynamie des Himmels, and in 1851 the essay for which he is perhaps more generally known in popular science, that upon the mechani cal equivalent of heat, in which lie developed and expanded the principles laid down in his former papers. His argument is that the sun's power is the source of all energy on the earth, nature storing up the light and heat, and niolding it into permanent forms, from which other kinds of energy may be derived. In this way various potential con
ditions are formed, plants storing up power to be afterward transfeued to animals and diffused in motion or work; or the plants in the form of wood and coal may liberate their forces by combustion. He determined the numerical relation between heat and work, ,and followed up his investigation by considering the vast amount of heat gener ated by gravity when the force continues its action through sufficient space; concluding that the gravitating force between the sun and the earth possessed a heat equivalent to a muss of 6,000 times the weight of the eartla, and that the light and heat of the suu are maintained by the constant impact of meteoric matter. In 1848 Dr. Mayer incurred the displeasure of many of his former friends by taking sides against the revolu tionists, and the attacks made upon his scientific investizations so affected him as to throw him iuto a sleepless condition which resulted in delirium, during which he leaped from a window. 30 it. high, sustaining severe injuries, from which, however, after a long time he recovered. His works have been published under the title Die illechanik der Warme, (Stuttgart, 186'7). The Copley medal was awarded to him by the royal society of London in 1871.