Nothing about
the grand, useful timekeeper, I argued, would disfigure the tree, for
it would look something like a big hawk's nest. "But that," he
objected, "would draw still bigger bothersome trampling crowds about
the place, for who ever heard of anything so queer as a big clock on
the top of a tree?" So I had to lay aside its big wheels and cams and
rest content with the pleasure of inventing it, and looking at it in
my mind and listening to the deep solemn throbbing of its long
two-second pendulum with its two old axes back to back for the bob.
One of my inventions was a large thermometer made of an iron rod,
about three feet long and five eighths of an inch in diameter, that
had formed part of a wagon-box. The expansion and contraction of this
rod was multiplied by a series of levers made of strips of hoop iron.
The pressure of the rod against the levers was kept constant by a
small counterweight, so that the slightest change in the length of the
rod was instantly shown on a dial about three feet wide multiplied
about thirty-two thousand times.
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