Julius Robert von Mayer, German physicist, c 1870s.
© Science Museum / Science & Society Picture Library
Photogravure after a painting or photograph of Julius Robert von Mayer (1814-1878). Mayer trained as a physician but is best remembered for his contribution to physics. In 1842 he discovered a numerical value for the mechanical theory of heat. His findings were dismised as an unsupported hypothesis, and it was the English physicist James Joule (1818-1889), who took credit for the discovery five years later. Mayer, angry at this injustice, attempted suicide and spent several years in mental institutions. It was only in 1863, when John Tyndall (1820-1893) lectured on Mayer's work, that he obtained the recognition he deserved. From a collection of portraits of scientists published by Photographische Gesellschaft, Berlin, c 1910. Dimensions: 460mm x 340mm.