Galileo
A celebrated mathematician, born 1564, who discovered the use of the pendulum. It is related that one morning he was in church and saw a lamp which was suspended by a silken cord from the ceiling, swinging to and fro after having been carelessly struck by one of the attendants. He noticed the regularity of the swing, comparing it with his pulse, and concluded that, by reason of its regularity, a simple pendulum might become a valuable agent in the measurement of time. In 1639, he published a treatise on the use of the pendulum in clocks, but there is no record of his having made one. The credit of actually putting a pendulum in a clock has been claimed for Richard Harris, of London, 1641; Vincent Galileo, son of the philosopher, 1649; and Huyghens, 1657. The weight of the evidence seems to be in favor of Huyghens as being the first to apply the Galilean theory in practice, but it is beyond dispute that the invention of the pendulum belongs to Galileo.