At the equator, one degree of longitude and latitude both cover about 111 kilometers, or just under 70 miles. When we get away from the equator, this starts getting tricky. Longitude lines.

This led to the formation of the Board of Longitude, which offered a £20,000 cash prize - equivalent to about £1.5m today - to anyone who could solve the “longitude problem”.

John Harrison created a device that helped sailors find longitude at sea, but it took another 250 years before he'd get credit for his most amazing invention.