Harrison’s H-1 clock makes its first sea voyage aboard the Centurion, sailing from England to Lisbon and back. John Harrison’s clock undergoes its first sea trial. This solves the problem of calculating longitude, which plagued navies around the world. Latitude can be measured with the Pole Star (in the Northern Hemisphere), but to calculate longitude, one must know the precise time due to the Earth’s rotation (or use alternative methods, as proposed by Galileo). There’s a wonderful little book by Dava Sobel on the subject. The simple clockmaker John Harrison defeats seemingly more advanced technologies on a subject even Newton and Galileo had explored. The problem was particularly acute among navies. The H-4 clock (the fourth version) was tested with great success by Captain James Cook on the 1772-1775 voyage.
