Viking sailors often used primitive navigation methods. To roughly determine latitude for example they observed the shadow of the gunwale on the rowing bench in their 100-foot-long boats.
• While they were sailing west Viking navigators would release ravens into the air. If the birds flew back on the same course, the Viking boats would continue their westward course, but if the birds flew in any other direction, the Vikings would follow them to new lands and new conquests.
• When the Phoenician navigator Hanno reported that he circumnavigated Africa in 500 B.C., he observed that the noon sun shone in the north at the southern end of Africa. Ancient learned men laughed, but today we accept this as proof that he did make the journey.
• No learned person ever argued with Columbus that the earth was flat. His opponents, who were right, contended that he had underestimated the size of the earth and that he could never sail from Spain to the Far East. In fact, he would have had to turn back if he hadn't stumbled across America.
, The compass that Columbus used on his historic first voyage was constructed with a fault and was imperfect.
· Most people believe the Cape of Good Hope is the southernmost point in South Africa. Actually, Cape Agulhas extends 65 kilometers farther south.
· Greenwich Mean Time, used throughout the world today as a standard time; was only adopted by most countries in 1884 at the International Meridian Conference. British ships, had based their time on the clocks in Greenwich, England, since the Royal Greenwich Observatory was founded in 1675, and many nations had emulated them at sea. By 1884 some 65 percent of the world's ships used Greenwich time and determined longitude from the Greenwich meridian.
• The sextant, the latest in a family of navigating instruments (including the astrolabe, quadrant, and octant! that measure the separation of two distant objects and help determine the time of day and geographical latitude, was perfected by John Hadley of England in 1731. His invention, was called Hadley's Octant because of the arc it measured an eighth (45°) of a complete circle. The name fell out of use, and today sextant is the term universally used, but Hadley's Octant lives on as the designation the French astronomer La Caille gave in 1752 to a group of stars in the southern hemisphere.
· The development of the modem chronometer began when Yorkshire inventor John Harrison won a British admiralty contest offering £20,000 to anyone who could devise a method of determining longitude within a half degree. The offer was the result of the great tragedy near the Scilly Islands off England in 1707, when an English fleet miscalculated its longitude and four ships went aground with the loss of 2,000 men.
• The great American navigator Nathaniel Bowditch was largely self-taught, having left school when 10 years old. So respected was his work on navigation that ships of all nations flew their flags at half-mast when he died in 1838.
• One of the world's most interesting collections of navigation instruments can be seen at the Peabody Museum in Salem, Massachusetts. Those designed and used by Salem native son Nathaniel Bowditch, the pioneer American navigator, whose birthplace stands a few blocks from the museum, form the nucleus of the collection. A leader of the East India Marine Society, Bowditch amassed a sizable collection and went on to write the authoritative New American Practical Navigator still in print today. These instruments range in purpose from determining a vessel's position at sea by the altitude of celestial bodies, through ascertaining direction, time, and speed, to drafting and computing.
