 On his second voyage, Cook used the K1 chronometer made by Larcum Kendall, which was the shape of a large pocket watch, in diameter.It was a copy of the H4 clock made by John Harrison, which proved to be the first to keep accurate time at sea when used on the ship "Deptford"s journey to Jamaica in 1761–62.He succeeded in circumnavigating the world on his first voyage without losing a single man to scurvy, an unusual accomplishment at the time.