589. If a weight be attached to a piece of string, the other end
of which hangs from a fixed point, we have what is called a simple
pendulum. The pendulum is of the utmost importance in science, as well
as for its practical applications as a time-keeper. In this lecture
and the next we shall treat of its general properties; and the last
will be devoted to the practical applications. We shall commence with
the simple pendulum, as already defined, and prove, by experiment,
the remarkable property which was discovered by Galileo. The simple
pendulum is often called the circular pendulum.