The Portuguese had coasted Africa, the Spanish South America, the English most of the east of North America, while Central America was known through the Spaniards.

Many of the islands of the Pacific Ocean had been touched upon, though not accurately surveyed, and there remained only the north-west coast of America and the north-east coast of Asia to be explored, while the great remaining problem of geography was to discover if the great southern continent assumed by Ptolemy existed, and, if so, what were its dimensions.

It happened that all these problems of coastline geography, if we may so call it, were destined to be solved by one man, an Englishman named JAMES COOK, who, with Prince Henry, Magellan, and Tasman, may be said to have determined the limits of the habitable land.
His voyages were made in the interests, not of trade or conquest, but of scientific curiosity; and they were, appropriately enough, begun in the interests of quite a different science than that of geography.

The English astronomer Halley had left as a sort of legacy the task of examining the transit of Venus, which he predicted for the year 1769, pointing out its paramount importance for determining the distance of the sun from the earth.

This transit could only be observed in the southern hemisphere, and it was in order to observe it that Cook made his first voyage of exploration.
There was a double suitability in the motive of Cook's first voyage.
The work of his life could only have been carried out owing to the improvement in nautical instruments which had been made during the early part of the eighteenth century.