he genius
to appreciate its importance. This was William Thomson, the present
Lord Kelvin, now known to all the world as among the greatest of natural
philosophers, but then only a novitiate in science. He came to
Joule's aid, started rolling the ball of controversy, and subsequently
associated himself with the Manchester experimenter in pursuing his
investigations.

But meantime the acknowledged leaders of British science viewed the
new doctrine askance. Faraday, Brewster, Herschel--those were the great
names in physics at that day, and no one of them could quite accept
the new views regarding energy. For several years no older physicist,
speaking with recognized authority, came forward in support of the
doctrine of conservation. This culminating thought of the first half
of the nineteenth century came silently into the world, unheralded and
unopposed. The fifth decade of the century had seen it elaborated and
substantially demonstrated in at least three different countries, yet
even the leaders of thought did not so much as know of its existence.
In 1853 Whewell, the historian of the inductive sciences, published a
second edition of his history, and, as Huxley has pointed out, he did
not so much as refer to the revolutionizing thought which even then was
a full decade old.

By this time, however, the battle was brewing. The rising generation
saw the importance of a law which their elders could not appreciate, and
soon it was noised abroad that there were more than one claimant to the
honor of discovery. Chiefly through the efforts of Professor Tyndall,
the work of Mayer became known to the British public, and a most
regrettable controversy ensued between the partisans of Mayer and those
of Joule--a bitter controversy, in which Davy's contention that science
knows no country was not always regarded, and which left its scars upon
the hearts and minds of the great men whose personal interests were
involved.

And so to this day the question who is the chief discoverer of the law
of the conservation of energy is not susceptible of a categorical answer
that would satisfy all philosophers. It is generally held that the first
choice lies between Joule and Mayer. Professor Tyndall has expressed the
belief that in future each of these men will be equally remembered in
connection with this work. But history gives us no warrant for such a
hope. Posterity in the long run demands always that its heroes shall
stand alone. Who re