gridiron pendulum

American  

noun

1. a clock pendulum having, as part of its shaft, an arrangement of brass and steel rods having different coefficients of expansion, such that the pendulum has the same length at any temperature.

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Etymology

Origin of gridiron pendulum

First recorded in 1745–55

Example Sentences

The “gridiron” pendulum consists of a group of alternate rods of steel and brass, so arranged that the expansion of the brass acts upwards and counteracts that of the steel downwards.

From Project Gutenberg

John Harrison, stimulated by these offers to increased exertion, in the year 1736 presented himself at Greenwich with one of his wonderful clocks, provided with the gridiron pendulum, which he exhibited and explained to the commissioners.

From Project Gutenberg

He remedied this by the invention of what is often called the gridiron pendulum, made of several bars of steel and brass, and so arranged as to neutralize and correct the tendency of the pendulum to vary in length.

From Project Gutenberg