‘Design-Society’ Cycle: A Case Study on the Story of Longitude - Principia Designae: Pre-Design, Design, and Post-Design - page 121

9.8 The Story of Longitude and John Harrison

John Harrison (1693-1776) was an English inventor and horologist, who solved one
of the most difficult problems of the eighteenth century: how to determine the
longitude of a ship at sea, saving many lives ( https://www.asme.org/engineering-
topics/articles/mechanisms-systems-devices/john-harrison ) . Harrison was fasci-
nated with watches, clocks, and other timepieces since the age of six when he
was sick with smallpox, and had to entertain himself with a watch his parents placed
on his pillow. At that time, watches were large, and it was easy to see how they
worked. Harrison's father was a carpenter, but also repaired clocks; Harrison started
assisting his father in his work as soon as he was old enough. Further on, he
combined his interest in woodworking and timepieces and started building clocks.
At 1713, at the age of 20, he completed his first grandfather clock. A year later,
Parliament offered a prize of 20,000 pounds to calculate a ship's precise longitude
at sea. Harrison decided to compete for this prize.
The existing principle of calculating longitude was the following. For every 15

travelled westward, the local time moved back by an hour. If the local time and time
at another known point on the Earth were known, the difference could be used to
calculate longitude. While the local time could be estimated by observing the sun,
no reference point such as GMT was available for calculation of the other time. The
only clocks then were pendulum clocks, which became inaccurate by a ship's
motion and temperature changes.
Determining longitude on land was relatively easy, due to a “ ... stable surface to
work from, a comfortable location to live in while performing the work and the
ability to repeat determinations over time made for great accuracy” ( http://en.
wikipedia.org/wiki/History_of_longitude ) . For longitude, early ocean navigators
had to rely on 'dead reckoning'—calculating one's current position by using a
previously determined position, and advancing that position based on known or
estimated speeds over elapsed time, and course ( http://en.wikipedia.org/wiki/
Dead_reckoning ) . This was inaccurate on long voyages out of sight of land.
To avoid problems with not knowing one's position accurately, navigators
sometimes relied on taking advantage of their knowledge of latitude, which was
relatively easy to calculate from declination of the sun. Sailing to the latitude of
their destination, they would turn toward their destination and follow a line of
constant latitude (Dunlap and Shufeldt 1972 ). However, this solution prevented a
ship from taking the most, or most favourable, route, extending the duration of the
voyage and increasing the risk of poor health or death to members of the crew, and
the resultant risk to the ship ( http://en.wikipedia.org/wiki/History_of_longitude ).
Navigation errors often resulted in shipwrecks. Motivated by a number of such
maritime disasters attributable to serious errors in reckoning position at sea, e.g. the
Scilly naval disaster of 1707 where a British naval fleet, along with its Admiral Sir
Cloudesley Shovell, sunk off the Isles of Scilly, the British government established
the Board of Longitude in 1714 ( http://en.wikipedia.org/wiki/Scilly_naval_disas
ter_of_1707 ) : “The Discovery of the Longitude is of such Consequence to