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Hoar, George Frisbie, 1826-1904

"Autobiography of Seventy Years, Vol. 1-2"

Silver has
always been a favorite metal with mankind from the beginning.
While gold may be the standard of value, it is too precious
to be a convenient medium of payment for small sums, such
as enter into the daily transactions of ordinary life. It
is said that you can no more have a double standard, or two
measures of value, than you can have a double standard, or
two measures of distance. But the compensating effect may
be well illustrated by what is done by the makers of clocks
for the most delicate measurements of time, such as are used
for astronomical calculations. The accuracy of the clock
depends upon the length of the pendulum and the weight which
the pendulum supports. If the disk at the end of the pendulum
be humg by a wire of a single metal, that metal expands and
shrinks in length under changing atmospheric influences, and
affects the clock's record of time. So the makers of these
clocks resort to two or three wires of different metals, differently
affected by the atmosphere. One of these compensates for
and supplements the other, so that the atmospheric changes
have much less effect than upon a single metal.


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