- Cook gathered accurate longitude measurements during his first voyage due to his navigational skills, the help of astronomer Charles Green and by using the newly published Nautical Almanac tables, via the lunar distance method—measuring the angular distance from the moon to either the sun during daytime or one of eight bright stars during night-time to determine the time at the Royal Observatory, Greenwich, and comparing that to his local time determined via the altitude of the sun, moon, or stars. On his second voyage Cook used the K1 chronometer made by Larcum Kendall, which was the shape of a large pocket watch, 5 inches (13 cm) 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, 1761–62.
Cook succeeded in circumnavigating the world on his first voyage without losing a single man to scurvy, an unusual accomplishment at the time. He tested several preventive measures but the most important was frequent replenishment of fresh food. It was for presenting a paper on this aspect of the voyage to the Royal Society that he was presented with the Copley Medal in 1776. Ever the observer, Cook was the first European to have extensive contact with various people of the Pacific. He correctly postulated a link among all the Pacific peoples, despite their being separated by great ocean stretches (see Malayo-Polynesian languages). Cook theorised that Polynesians originated from Asia, which scientist Bryan Sykes later verified. In New Zealand the coming of Cook is often used to signify the onset of colonisation.