Fix a rod, or tube, or telescope pointing at a star in the cast
or west, and the earth's revolution will be apparent in a moment,
turning the tube away from the star. Point it at stars about the
north pole, and those on one side will be found going in an opposite
direction from those on the other, and very much slower than those
about the equator. Anyone can try the pendulum experiment who has
access to some lofty place from which to suspend the ball. It was
tried in Bunker Hill Monument a few years ago, and is to be tried
in Paris, in the summer of 1879, with a seven-hundred-pound pendulum
and a suspending wire seventy yards long. The advance and retrograde
movements of planets can be illustrated by two persons walking
around a centre and noticing the place where the person appears
projected on the wall beyond.
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