These earthworks are all that remain of the Norman motte & bailey castle at
Barrow-upon-Humber but they are nevertheless impressive (Map ref: TA 065 225).
Famous son of this town is John Harrison 1693-1776, the inventor of the first marine chronometer - a clock designed to keep accurate time whilst at sea, essential for calculating a ship's longitude.
Although John was born near Wakefield, the family moved to Barrow-upon-Humber soon afterwards and it was here that he grew up.
He trained in his father's joiners shop but he developed an interest in clock-making. After almost 300 years, one of his is still in good working order at nearby Brocklesby.
As trans-oceanic journeys became more frequent, a system was needed to plot a
ship's accurate position on a chart. In October 1707 in thick fog, part of the
English fleet under the command of Sir Cloudesley Shovell ran aground in the
Scilly Isles even though their navigation calculations had indicated they were
in safe waters. Over 2000 men died in that incident and the Government
established a prize of up to £20,000 for anyone who could find a method of
calculating longitude at sea.
To accurately know their ship's position, a crew needed to be able to calculate its latitude and its longitude. The former could be obtained by measuring the elevation of the Pole Star but longitude was not so easy to calculate using astronomy. Harrison's method was to create a clock that could keep accurate time of the home port. Using sun sights, the crew could calculate "local" time at sea and, by comparing with the clock, they could find the difference in time and work out their longitude.
The earth rotates 360 degrees in 24 hours (1440) minutes. Therefore every 4 minutes, the earth rotates 1 degree of longitude. If a ship were 1 hour behind the time at their home port, they knew that they were 15 degrees west of their starting point. Political wranglings stopped him winning the actual prize but he was eventually paid an equivalent sum by parliamentary decree.
Barrow Haven is still in
use as a small port today.
The photo shows a coastal vessel "Tramp" offloading timber.
Nearby a tileworks is still in production.