Before global positioning systems and modern mapmaking, the concept of longitude was just a dream. Without its guidance, navigation in the 1700s was both unpredictable and deadly until one man solved the mystery. Richard Dreyfuss narrates this dramatic re-creation of longitude's difficult birth and the remarkable history-making life of a country carpenter named John Harrison. Go back in time to see history, and longitude, in the making.

Encoded with permission for digital streaming by Infobase on December 08, 2013. Learn360 is distributed by Infobase for Films for the Humanities & Sciences, Cambridge Educational, Meridian Education, and Shopware.

Intro: Lost at Sea (1:02) -- Navigation and Economic Power (1:46) -- Sailing Problems in the 1700s (1:47) -- Measuring Latitude in the 18th Century (2:20) -- Disaster at Sea: HMS Association (2:15) -- A Challenge for Scientists and Madmen (4:02) -- A Functioning Harrison Clock (2:58) -- Louis XIV's Astronomers (4:54) -- Perfecting Accuracy By Experimentation (4:31) -- Harrison Presents His Sea Clock (3:14) -- Sea Clock H1 (1:42) -- Successful Test is Not Enough (3:44) -- Nevil Maskelyne's Moon Tables (3:33) -- Switch to Watchmaking Techniques (2:37) -- H4's Testing Voyage to Barbados (3:09) -- Harrison Denied Prize (5:38) -- Reward Granted to Harrison Family (2:22) -- The New Navigation - GPS (0:59) -- Credits: Lost at Sea: The Search for Longitude (0:54).