Actually, his pendulum clocks never made the cut. He could not figure out how to compensate for torque, when the ship tacked. He made a leap, to adopting the basic design of a pocket watch, with a balance wheel, instead of a pendulum.
Fascinating film was produced in 2000 dramatizing both Harrison’s work, and the restoration of his clocks in the 1920s and 30s by Rupert Gould. As it happens, I rewatched “Longitude” only a couple days ago.
