English: A temperature compensated pendulum invented by British instrument maker Edward Troughton. It is a variant of the gridiron pendulum invented in 1726 by John Harrison, and like that pendulum is made of two metals with different coefficients of thermal expansion. Assume the outside crosspieces are made of steel, while the horizontal braces are made of brass. If the temperature increases, the crosspieces will expand making the pendulum longer, but the horizontal braces will expand more, reducing the outside angles of the rhomboids, thus making the pendulum shorter. With the correct geometry these two effects will cancel out, and the pendulum's length, and its period will remain unchanged with temperature. The Troughton pendulum, with its complicated compensation mechanism and many joints, probably would have been greatly inferior in accuracy to the gridiron pendulum, and there is no record it was used in any clocks.