Technikatörténeti szemle 19. (1992)

KÖNYVISMERTETÉS - Papers of the First „MINERALKONTOR” International Conference on the History of Chemistry and Chemical Industry (Veszprém, 12-16 August, 1991)

JÁNOS LISZI* ÁNYOS JEDLIK: ON THE HEAT. A HUNGARIAN MANUSCRIPT FROM THE MIDDLE OF THE 19TH CENTURY The manuscript was prepared between 1847 and 1851 in Hungarian language. It is divided into five chapters having the following titles: On the Degrees of Heat, On the Propagation of Heat, On the Heat Capacity of Bodies, On the Operation of Heat, and On the Sources of Heat. The author of the manuscript Ányos Jedlik was blessed with a long life — born in 1800, died in 1895 — he was a contemporary of — among others — Avogadro, Clausius, Darwin, Garibaldi, Helmholtz, Joule, Lincoln, Liszt, Maxwell, Siemens and Verdi. In 1817 he was admitted to the Benedictine order. He was a priest and a teacher for 53 years, first at the Benedictine secondary school of Győr. He built the first electromagnetic motor in the world there in 1829. From 1831 he taught physics at the Royal Academy of Pozsony, then — from 1840 until his retirement at the age of 78 — he was the professor of the Department of Physics and Mechanics at the University of Pest. His successor at the department was Loránd Eötvös, the world-famous physicist. The two main scopes of his activity were electricity and optics. In both fields he achieved outstanding results. In 1836 — preceding Siemens — he invented the generator. The dynamo principle was put into words by him as follows: „what if, by any chance, a considerable electric current were led — before being actually used — through the coils wound around the magnetic poles? If this made strength of poles stronger, the electric current would also be made stronger whereby causing the poles to become stronger as well, which, again, would give rise to a stronger flow of current and so on until a certain limit is reached." Being a skillful experimentalist, he constructed the apparatus as well. Among his optical devices I mention two. He constructed a ruling engine capable of producing optical gratings with 2093 lines per mm. Between 1862 and 1865 he constructed an interferometer using a pair of mirrors to determine the wavelength of light. The device — reinvented some 20 years later — became known world-wide as Michelson interferometer. Although he had 76 inventions realized completely or in part, he published only a few. Why? Being a Benedictine monk he was very modest. That could be a possible reason. Also, other reasons hold him back. Such a case could be the •University of Veszprém, H-8201 Veszprém, Pf. 158.