The German Genius

India Company. 2 It was during a stopover in Djakarta in the summer of 1840 that he made his most famous observation. In the manner of the day, he let the blood of several European sailors who had recently arrived in Java. He was surprised at how red their blood was and inferred that it was more than usually vivid owing to the high temperatures in Indonesia, which meant the sailors’ bodies required a lower rate of metabolic activity to maintain body heat. Their bodies had extracted less oxygen from their arterial blood, making the returning venous blood redder than it would otherwise have been.
    Mayer was struck by this observation because it seemed to him to be self-evident support for Justus von Liebig’s theory that animal heat is produced by combustion—oxidation—of the chemicals in the food taken in by the body. In effect, he was observing that chemical “force” (as the term was then used), which is latent in food, was being converted into (body) heat. Since the only “force” that enters animals is their food—their fuel—and the only form of force they display is activity and heat, these two forces must always—by definition—be in balance.
    Mayer originally tried to publish his work in the prestigious Annalen der Physik und Chemie , edited by Johann Christian Poggendorff, but was rebuffed. 3 His first published work, “Bemerkungen über die Kräfte der unbelebten Natur” (“Remarks on the Forces of Inanimate Nature”), was therefore published in the Annalen der Chemie und Pharmacie in 1842, and it was here that he argued for a relationship between motion and heat, that “motion and heat are only different manifestations of one and the same force [which must] be able to be converted and transformed into one another.” Mayer’s ideas did not have much impact at the time, though presumably the editor of the Annalen der Chemie und Pharmacie , none other than Justus von Liebig, thought them worth printing. 4
    Julius Mayer’s story is tidy. The historian of science Thomas Kuhn has pointed out, however, that between 1842 and 1854, no fewer than twelve scientists had arrived at some version of the idea that became known as the “conservation of energy.” The word “energy” was new at mid-century, but by 1900 all of physics would revolve around the concept. 5 Kuhn points out that, of these twelve pioneers, five came from Germany, one from Alsace, and one from Denmark, areas of German influence. He put this preponderance of Germans down to the fact that “many of the discoverers of energy conservation were deeply predisposed to see a single indestructible force at the root of all natural phenomena.” He suggested that this root idea could be found in the literature of Naturphilosophie . “Schelling, for example, [and in particular] maintained that magnetic, electrical, chemical and finally even organic phenomena would be interwoven into one great association.” 6 Von Liebig studied for two years with Schelling.
    T HE A DVENT OF P HYSICS AS W E K NOW I T
     
    So far as physics was concerned, the first half of the nineteenth century saw some crucial changes in approach and even in vocabulary, changes that reflected the evolving nature of physics. In the late eighteenth century, for example, the term “physics” had referred to the natural sciences in general. In the early nineteenth century, the same word came to mean the study of mechanics, electricity, and optics, generally employing a mathematical and/or experimental methodology. 7 By mid-century, “there emerged a distinctive science of physics that took quantification and the search for mathematical laws as its universal aims.” In 1824, for example, the curator of the University of Heidelberg proposed that a “mathematical seminarum” be established there, to be modeled on the increasingly successful seminars in philology that, as we have seen, were being credited with improving German classical education. Other universities followed. 8 Moritz Stern, extraordinary professor of mathematics at Göttingen, called for much the same thing, while the Berlin Physical Society was founded in 1845. 9
    Research, as already noted, began to acquire greater prestige, and physics was no different from other disciplines. The Annalen der Physik increasingly devoted its pages to the research of German scientists and less to the translations of papers from foreign journals. Founded in 1790, the Annalen was itself a symptom of the changes taking