Arctic Dreams

by Barry Lopez

not until John Harrison built his first chronometer in 1735 would there be a reliable way to determine longitude. The charts and maps available to expeditions, especially for westering mariners, were of little help. Too much of the information was whimsical or groundless, and updating maps often meant contending with theoretical concepts of geography with which practical mariners had little patience. Furthermore, with no way to determine longitude and scant information on compass variation in different parts of the hemisphere, they found it hard to place new lands accurately and so improve old maps. The Zeno map (1558), a fictitious compilation showing many large islands in the western North Atlantic, was of such intimidating authority, on the other hand, that even John Davis believed he had to “harmonize his work with universally received errors.”