John Harrison's Struggle Continues[no description provided]
Today is John Harrison's 352nd birthday, and Google has a doodle to celebrate. Harrison was rescued from historical obscurity by Dava Sobel's excellent book Longitude, which documented Harrison's struggle to first build and then demonstrate the superiority of his clocks to the mathematical and astronomical solutions heralded by leading scientists of the day. Their methods were complex, tedious and hard to execute from the deck of a ship.
To celebrate, I'd like to share this photo I took at the Royal Museums Greenwich in 2017:
(A Full size version is on Flickr.)
As the placard says, "First produced in 1768, this worksheet gave navigators an easy process for calculating their longitude using new instruments and the Nautical Almanac. Each naval ship's master was required to train with qualified teachers in London or Portsmouth in order to gain a certificate of navigational competence." (Emphasis added.)