 On the 23rd of July in 1847, Helmholtz gave an address, “The Conservation of Force,” at the Physical Society. “Force” [Kraft], as Helmholtz uses it, is equivalent to the modern term “energy.” Helmholtz’s address was very well received by the Society, but Helmholtz was forced to publish it as a pamphlet after Poggendorff rejected it for his Annalen as too speculative. 