1. Navigational History
(Mariners Education/Navigation)

... was invented, eventually replacing earlier cross-staffs and Davis quadrants. This had the immediate effect of making latitude calculations much more accurate. Four years later, the first marine chronometer ...

2. Marine Navigation
(Mariners Education/Navigation)

... 151° east. New York City has a longitude of about 74° west. For most of history, mariners struggled to determine precise longitude. The problem was solved with the invention of the marine chronometer. ...