THE STORY OF MAPS (397 pp.)Lloyd A. BrownLittle, Brown ($7.50).
Until late in the 18th Century, no ship's captain was ever dead sure of his position at sea. It was not uncommon, on long voyages, to miscalculate port by a hundred miles and miss island destinations entirely. Reason: no one had ever discovered a means of determining longitude.
In 1598, Philip III of Spain vainly offered a fat pension to the man who could solve the mystery. In 1707, a British fleet homeward bound from Gibraltar groped about blindly for twelve days in bad weather before it ran aground on the Scilly Islands...