yndall gave a course of lectures on heat as a mode of
motion, and was even then sneered at by some scientific men for his
temerity. Tait, of Glasgow, was particularly obstreperous. To-day
nobody questions it; and we go back to Sir Humphry Davy and Count
Rumford for our proofs, too. It was proved scientifically proved then;
but it took the world all these years, even the scientific world, to
get rid of its prejudices in favor of some other theory, and see the
force of the proof.

Now, in the second place, it was held originally that light was a
series of corpuscles that flew off from a heated surface; but Thomas
Young, about the year 1804, demonstrated the present accepted theory of
light. But it was fought for years. Only after a long time did the
scientific world give up its prejudice in favor of the theory that was
propounded by Newton. But to-day we go back to Young, and see that he
demonstrated it beyond question.

In the third place, take another fact. Between 1830 and 1845 Faraday
worked out a theory of electrical and magnetic phenomena. It was proved
to be correct. Maxwell, a famous chemist in London, looked over the
matter, and persuaded himself that Faraday was right; but nobody paid
much attention to either of them; until after a while the scientific
world, through the work of its younger men, those least wedded to the
old-time beliefs, conceded that it must be true.

The Nebular Theory was proved and worked out by Kant more than a
hundred and thirty years ago. In 1799 Laplace worked it out again; but
it was a long time before it was accepted. And now we go back to Kant
and Laplace for our demonstration.

Darwin's "Origin of Species" was published in 1859. But it was
attacked by scientists as well as theologians on every hand. Huxley
even looked at it with a good deal of hesitancy before he accepted it.
To-day, however, everybody goes back to the "Origin of Species," and
finds the whole thing there, demonstration and all.

Lyell published a book on the antiquity of man in 1863. It was twenty-
five years before all the scientific men of the world were ready to
give up the idea that man had been on the earth more than six or eight
thousand years.

So we find that it is not theologians only; it is scientists, too, that
find it difficult to accept new ideas. I know scientific men among my
personal friends who are simply incapable of being hospitable to an
idea that would compel them to reconstruct a theory