“It might be expected that plumb lines, set up in various locations, if extended downward, would all pass through a single point, the center of Earth. But this is not the case.” — Why the Greenwich Meridian Moved, by Stephen Malys et. al., 2015 Both John Harrison’s clocks and lunar distance tables assumed that the […]
navigation
Posted inField Notes
Longitude and the Prime Meridian, Part 1
“I have been extremely ill used by the gentlemen who I might have expected better treatment from.” — John Harrison, on his struggle to receive the reward for solving the Longitude Problem For centuries, the Royal Navy was the mightiest maritime force in the world, helping a small country on the edge of Europe establish […]
Posted inLife + Outdoors
A Question of Longitude
Last week, we saw how, starting in the late 1600s, astronomers published almanacs of predictable celestial events, in particular the eclipses of Jupiter’s four bright (“Galilean”) moons, allowing travelers anywhere in the world to compare their local time with almanac time, thus giving them their longitudes. Let’s see how that worked in real life, especially […]