H-1

Harrison's first sea clock. Harrison spends five years building it. The H-1 still exists today and weights seventy pounds, enclosed in a 4 x 4 x 4 foot cabinet. It worked spectacularly and passed tests on numerous occasions. Halley was converted, among others.

H-2

H-1 could have easily passed the Board of Longitude's requirements but Harrison spent his presentation before the Board complaining about H-1's errors. He asked for a small loan to build a second clock and the board agreed so long as Harrison agreed that the clock would be available for public use. In two years, he produced the H-2 but became dissatisfied with it before presenting it to the board. Because of this, he wanted to try again and H-2 was never used at sea.

H-3

After he gave up on H-2, Harrison would spend the next twenty years building the H-3, emerging only to collect...