Bimetallic+Strip+and+Chronometer

Started in 1740, this third timekeeper took Harrison nearly 19 years to build and adjust, although it was not to win him the great longitude prize: he found that he just could not persuade the two large, heavy, circular balances to keep time well enough. Nevertheless, H3 incorporates two extremely important inventions, both relevant today: the bimetallic strip (still in use worldwide in thermostats of all kinds) and the caged roller bearing, a device found in nearly all modern mechanical engineering.

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