About a century since it became known, that when two clocks are in
action upon the same shelf, they will disturb each other: that the
pendulum of the one will stop that of the other; and that the pendulum
that was stopped will after a while resume its vibrations, and in its
turn stop that of the other clock. When two clocks are placed near
one another in cases very slightly fixed, or when they stand on the
boards of a floor, they will affect a little each other’s pendulum.
Mr. Ellicote observed that two clocks resting against the same rail,
which agreed to a second for several days, varied one minute thirty-six
seconds in twenty-four hours when separated. The slower, having a
longer pendulum, set the other in motion in 16-1/3 minutes, and stopped
itself in 36-2/3 minutes.