MAYER, JULIUS ROBERT (1814–1878)

In the early nineteenth century many scientists had glimmerings of the conservation-of-energy principle. The three most important among these were the Frenchman Marc Séguin, the American-born, well-travelled soldier of fortune Benjamin Thompson, and the chief engineer of the city of Copenhagen, Ludwig Colding.

The three men whose work later in the nineteenth century was crucial in bringing clarity to this principle were two Germans, the physician Julius Robert Mayer and the great polymath Hermann von Helmholtz, and the British amateur scientist James Joule. In a lecture delivered by Helmholtz on February 7, 1854, in Königsberg on "The Interaction of Natural Forces," he referred to Mayer as "the founder" in 1842 of the principle of conservation of energy and acknowledged Mayer's priority in this discovery over Colding (1843), Joule (1843), and Helmholtz himself (1847). Rudolf Clausius agreed with Helmholtz and put Mayer in touch with the British physicist John Tyndall, who quickly became Mayer's English champion in his long-drawn-out priority dispute with Joule and his British supporters, William Thomson (Lord Kelvin) and George G. Stokes.

MAYER'S LIFE AND CONTRIBUTIONS TO SCIENCE

Julius Robert Von Mayer was born in 1814 in Heilbronn, a small town on the Neckar river, halfway between Heidelberg and Stuttgart. Interested in science as a youth, he decided on a career in medicine, and in 1832 began his medical studies at the University of Tübingen. After completing his studies there in 1838, he received his M.D. degree.

In February 1840, Mayer embarked for a year as physician on a freighter carrying cargo to Jakarta in the East Indies, just south of the equator. In Jakarta he noticed that sailors' venous blood was a much brighter red than he had observed in patients back in Germany. He surmised that this change was due to the hot climate and the reduced oxidation needed to preserve normal body temperature. This stimulated him to thinking more generally about how heat affects human metabolism. This interest in heat, work, and what is now called energy became the passion of Mayer's life.

Mayer returned to Heilbronn in 1841, began his medical practice, and eventually became chief surgeon of the town. In his free time he did some experiments and struggled with difficult, abstract concepts in an attempt to understand the nature of energy. He knew so little physics from his one semester of the subject at Tübingen that many of the papers he submitted for publication were rejected as incompetent by the important scientific journals of the day. He was forced to publish most of his writings at his own expense, and so their circulation was confined primarily to Heilbronn residents.

The first published results of Mayer's work appeared in the March 1842 issue of Liebig's Annalen der Chemie und Pharmacie in an article entitled "Remarks on the Forces of Inanimate Nature." It contained a great deal of philosophy and some inaccurate science, and yet buried among these distracting elements was the essence of the conservation-of-energy principle. Perhaps more important to scientists, the article contained the first quantitative attempt to determine the relationship of the "calorie" (a unit of heat) to what is now called the "joule" (a unit of energy).

Mayer's calculations were based on his conviction that there is a definite quantitative relationship between the height from which a mass falls to the ground and the heat generated when it strikes the ground. Here he was stating his conviction that energy is conserved in this process if heat is considered a form of energy. He calculated the ratio of the joule to the calorie, and found that it was equal to 3.59 J/cal, which differs considerably from today's accepted value of 4.18 J/cal. His whole approach to the problem was correct, however, and his numerical result was certainly of the right order-of-magnitude, but he had used inaccurate values for some constants needed in his calculation.

Few details of his research were given in Mayer's 1842 paper, but in 1845 he published (at his own expense) his most original and comprehensive paper, "Organic Motion and Its Relation to Metabolism," in which he gave full details of his earlier work. In 1848 he also published, again privately, "Contributions to Celestial Dynamics," in which he made the interesting conjecture that the source of the energy radiated by the sun was its constant bombardment by high-energy meteors.

Mayer had married in 1842, and for the first few years his marriage was a very happy one, but then his life began to fall apart. Between May 1845 and August 1848 three of his children died. A nasty priority controversy with Joule became public when their claims were read and discussed by the Academy of Science in Paris. Mayer was upset that his writings on energy conservation were not more widely read, and that they often were not appreciated by the few scientists who did read them. And, as the final blow, he was accused by local scientists of being more a mad philosopher than a competent scientist.

Finally on May 28, 1850, in a fit of despair, Mayer threw himself out of his bedroom window to the street thirty feet below, but escaped without serious injury. He spent three years in mental hospitals and did little scientific work of value after his release in 1853, although he was able to return to limited service as a physician in Heilbronn.

Physicists around the world gradually came to appreciate Mayer's scientific work, but by this time they were unsure whether he was still alive and, if so, what his mental condition was. In his later years he finally reaped some fruit from his scientific labors. In 1859 he received an honorary doctorate from the University of Tübingen. This was followed in 1871 by his reception of the Copley Medal from the Royal Society of London, and then the Prix Poncelet from the Paris Academy of Sciences. It is unknown how appreciative Mayer was of this belated notoriety when he died of tuberculosis in 1878.

Joseph F. Mulligan

BIBLIOGRAPHY

Caneva, K. L. (1993). Robert Mayer and the Conservation of Energy. Princeton, NJ: Princeton University Press.

Friedländer, S. (1905). Julius Robert Mayer. Leipzig: T. Thomas.

Kuhn, T. S. (1977). "Energy Conservation as an Example of Simultaneous Discovery." In T. S. Kuhn: The Essential Tension. Chicago: University of Chicago Press.

Lindsay, R. B. (1973). Robert Mayer, Prophet of Energy. Elmsford, NY: Pergamon Press.

Schmolz, H., and Weckbach, H. (1964). Robert Mayer, Sein Leben und Werk in Documenten. Heilbronn: Anton H. Konrad Verlag.

Turner, R. S. (1974). "Mayer, Julius Robert." In Dictionary of>Scientific Biography, Vol. 9, ed. C. C. Gillispie. New York: Scribner.