First, we will imagine
a balance with its spring such as we find in fine marine chronometers.
It has small pivots running in highly-polished jewels; such pivots are
perfectly cylindrical, and no larger than are absolutely necessary to
endure the task imposed upon them--of carrying the weight of the balance
and endure careful handling.
To afford the necessary vibrations a spring is fitted, usually of a
helical form, so disposed as to cause the balance to vibrate in arcs
back and forth in equal time, _provided these arcs are of equal extent_.
It is now to be taken note of that we have it at our disposal and option
to make these arcs equal in time duration, i.e., to make the long or
short arcs the quickest or to synchronize them. We can readily
comprehend we have now established a very perfect measure of short
intervals of time. We can also see if we provide the means of
maintaining these vibrations and counting them we should possess the
means of counting the flights of time with great accuracy.
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