On the motion of fluids arising from different degrees of heat
According to Jacobi, a treatise with this title was read to the Berlin Academy on January 19, 1764. According to St. Petersburg Academy records, it was presented to that Academy on August 23, 1764.
In this paper, Euler improves on the ideas that he first suggested in E225. It contains the first correct physical explanation of convection currents as the result of the slight compressibility of a heavy fluid. Further, it strongly suggests the theory of line integrals and Kelvin diaphragms. One key idea Euler devleops in this paper is that the motion of a whole fluid mass is induced by different degrees of heat rather than the "internal motion considered by many to constitute heat." He also considers the situation of water in a vessel for which one part is hotter, and argues that the water in the lower portion of the vessel will "continually rise from the cold part to the hot, and contrariwise, in the higher portion will be carried down from the hot part toward the cold." Euler spends the remainder of the paper analyzing this type of flow in tubes.
Original Source Citation
Novi Commentarii academiae scientiarum Petropolitanae, Volume 11, pp. 232-267.
Opera Omnia Citation
Series 2, Volume 12, pp.244-271.