edly.

"At least I knew his name, Dad--give me credit for that," piped Steve.

"That was something, certainly," Mrs. Tolman declared, joining in the
laugh.

"Well, since neither of us can furnish the story, I don't see but that
you will have to do it, Dad," Doris said mischievously.

"It would be a terrible humiliation if I should discover that I could
not do it, wouldn't it?" replied Mr. Tolman with a smile. "In point of
fact, there actually is not a great deal more that it is essential for
one to know. It was by perfecting the engines of the Newcomen type and
adding to them first one and then another valuable device that Watt
finally built up the forerunner of our present-day engine. The
progression was a gradual one. Now he would better one part, then some
other. He surrounded the cylinder, for example, with a jacket, or
chamber, which contained steam at the same pressure as that within the
boiler, thereby keeping it as hot as the steam that entered it--a very
important improvement over the old idea; then he worked out a plan by
which the steam could be admitted at each end of the cylinder instead of
at one end, as was the case with former engines. The latter innovation
resulted in the push and pull of the piston rod. So it went."

"How did Watt come to know so much about engines?" asked Stephen.

"Oh, Watt was an engineer by trade--or rather he was a maker of
mathematical instruments for the University of Glasgow, where he came
into touch with a Newcomen engine. He also made surveys of rivers,
harbors, and canals. So you see it was quite a consistent thing that a
man with such a bent of mind should take up the pastime of experimenting
with a toy like the steam engine in his leisure hours."

"Did he go so far as to patent it, Henry?" Mrs. Tolman questioned.

"Yes, he did. Many of our scientists either had not the wit to do this,
alas, or else they were too impractical to appreciate the value of their
ideas. In consequence the glory and financial benefit of what they did
was often filched from them. But Watt was a Scotchman and canny enough
to realize to some extent what his invention was worth. He therefore
obtained a patent on it which was good for twenty-five years; and when,
in 1800, this right expired he retired from business with both fame and
fortune."

"It is nice to hear of one inventor who got something out of his toil,"
Mrs. Tolman observed.

"Indeed it is. Think of the many men who have slaved d