d oxygen--more particularly by
the transformation into motion of electricity obtained by chemical
means."(1)

MAYER AND HELMHOLTZ

Here, then, was this obscure German physician, leading the humdrum life
of a village practitioner, yet seeing such visions as no human being in
the world had ever seen before.

The great principle he had discovered became the dominating thought of
his life, and filled all his leisure hours. He applied it far and wide,
amid all the phenomena of the inorganic and organic worlds. It taught
him that both vegetables and animals are machines, bound by the same
laws that hold sway over inorganic matter, transforming energy, but
creating nothing. Then his mind reached out into space and met a
universe made up of questions. Each star that blinked down at him as he
rode in answer to a night-call seemed an interrogation-point asking,
How do I exist? Why have I not long since burned out if your theory
of conservation be true? No one had hitherto even tried to answer that
question; few had so much as realized that it demanded an answer. But
the Heilbronn physician understood the question and found an answer.
His meteoric hypothesis, published in 1848, gave for the first time a
tenable explanation of the persistent light and heat of our sun and the
myriad other suns--an explanation to which we shall recur in another
connection.

All this time our isolated philosopher, his brain aflame with the glow
of creative thought, was quite unaware that any one else in the world
was working along the same lines. And the outside world was equally
heedless of the work of the Heilbronn physician. There was no friend to
inspire enthusiasm and give courage, no kindred spirit to react on this
masterful but lonely mind. And this is the more remarkable because there
are few other cases where a master-originator in science has come upon
the scene except as the pupil or friend of some other master-originator.
Of the men we have noticed in the present connection, Young was the
friend and confrere of Davy; Davy, the protege of Rumford; Faraday, the
pupil of Davy; Fresnel, the co-worker with Arago; Colding, the confrere
of Oersted; Joule, the pupil of Dalton. But Mayer is an isolated
phenomenon--one of the lone mountain-peak intellects of the century.
That estimate may be exaggerated which has called him the Galileo of the
nineteenth century, but surely no lukewarm praise can do him justice.

Yet for a long time his work