Voyage of Discovery

One of the first to penetrate this conceptual tangle was Robert Mayer, a German
physician and physicist who spent most of his life in Heilbronn, Germany. Mayer
was a contemporary of James Joule (chapter 5), and like Joule, he was an amateur
in the scientific fields that most absorbed his interest. His university training was
in medicine, and what is known of his student record at the University of Tu¨ -
bingen shows little sign of intellectual genius. He was good at billiards and cards,
devoted to his fraternity, and inclined to be rebellious and unpopular with the
university authorities; eventually he was suspended for a year. With hindsight,
we can see in Mayer’s reaction to the suspension—a six-day hunger strike—
evidence for his stubbornness and sensitivity to criticism, and even some forewarning
of his later mental problems.
Mayer’s youthful behavior was not that of an unmitigated rebel, however;
when the Tu¨ bingen authorities permitted, he returned, finished his dissertation,
and passed the doctoral examination. But he was still too restless to plan his
future according to conventional (and family) expectations. Instead of settling
into a routine medical practice, he decided to travel by taking a position as ship’s
surgeon on a Dutch vessel sailing for the East Indies. He found little inspiration on this trip, either in the company of his fellow officers or in the quality and
quantity of the ship’s food. But to Mayer the voyage was worth any amount of
hunger and boredom.
Mayer tells us, in an exotic tale of scientific imagination, of an event in Java
that set him on the intellectual path he followed for the rest of his life. On several
occasions in 1840, when he let blood from sailors in an East Java port, Mayer
noticed that venous blood had a surprisingly bright red color. He surmised that
this unusual redness of blood in the tropics indicated a slower rate of metabolic
oxidation. He became convinced that oxidation of food materials produced heat
internally and maintained a constant body temperature. In a warm climate, he
reasoned, the oxidation rate was reduced.
For those of us who are inclined toward the romantic view that theoreticians
make their most inspired advances in intuitive leaps, this story and the sequel
are fascinating. Mayer’s assumed connection between blood color and metabolic
oxidation rate was certainly oversimplified and partly wrong, but this germ of a
theory brought an intellectual excitement and stimulation Mayer had never before
experienced. It did not take him long to see his discovery as much more
than a new medical fact: metabolic oxidation was a physiological conversion
process in which heat was produced from food materials, a chemical effect producing
a thermal effect. Mayer was convinced that the chemical effect and the
thermal effect were somehow related; to use the terminology he adopted to express
his theory, the chemical reaction was a “force” that changed its form but
not its magnitude in the metabolic process. And most important in Mayer’s view,
this interpretation of metabolic oxidation was just one instance of a general
principle.