Surveying and George Washington

One of our nation's most famous surveyors was our first president, George Washington (1732-99). Born in Virginia, he had little or no formal schooling, but taught himself mathematics and surveying. At the age of 17 he was invited to join a party to survey lands west of the Blue Ridge Mountains. His journey led him to take a lifelong interest in the development of western lands.

In July of 1749 he got his surveying license and that same summer he was appointed official surveyor for Culpeper County. During the next two years he made many surveys for landowners on the Virginia frontier. In 1770 he took part in the survey of 15,000 acres of land in the Ohio Valley.

The Chronometer and John Harrison (1693-1776)

John Harrison, a British carpenter turned clock maker, built the first chronometer (an extremely accurate clock) capable of keeping precise time at sea, making possible the determination of longitude. In locating the longitude of a ship at sea, an error of four seconds will cause an error in position of approximately a mile. Harrison's chronometer determined longitude to within a maximum error of 30 miles, an unheard of feat at the time.

Lines of latitude and longitude (the two co-ordinates that specify the location of a place on the earth's surface), first started to appear on maps at least three centuries BC. The equator marked the zero-degree parallel of latitude; hence, latitude is fixed by laws of nature. Finding longitude is a different story, though, as any line drawn from pole to pole may serve as well as any other for a starting line of reference. Early maps had zero-degree longitude running through such diverse places as Africa, Rome, Copenhagen, Jerusalem, St. Petersburg, Paris, Philadelphia, and finally London, which is its current location.

Gauging latitude was easy for a sailor. All he had to know was the length of the day, or the height of the sun, or certain stars above the horizon. However, to know longitude, the sailor needed to know what time it was aboard ship and also the time at the home port or another place of known longitude ­at that very same moment. This precise knowledge was unattainable: the only accurate timepiece, the pendulum clock, would slow down, speed up, or stop running on a rolling ship.

In 1707, 2000 lives were lost when an English fleet unexpectedly struck rocks off the southwestern tip of England, over 100 miles off course. To prevent any more major tragedies, the British government set up its famed Longitude Act of 1714 and put up a prize of 20,000 pounds (several million dollars in today's currency) for a "Practicable and Useful" means of determining longitude.

Harrison set about winning the prize. He first made several remarkable wooden clocks that were the most accurate timekeepers of their day. Then, in 1737, he devised a "sea clock," which used a pair of dumb-bells linked by springs in place of a swinging pendulum. H1, as it was known, was tested by the Admiralty and proved a great success. Something of a perfectionist, Harrison then proceeded to improve his design, making a number of innovations along the way, including a bimetallic strip to compensate for temperature variations. Twenty-four years later he produced his masterpiece, H4. The clock was an oversized pocket watch, being five inches in diameter and weighing only three pounds.

Unfortunately for Harrison, now almost 70, the government proceeded to add further requirements to win the award. Harrison spent another 10 years working on H5 and in 1773, with the intervention of King George III, he was awarded his money. Shortly before Harrison's death in 1776, Captain James Cook proved the true value of the chronometer on his second voyage to the Pacific, where he used it accurately to map Australia and New Zealand.