According to Dava Sobel's Longitude The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of his Time, many different  methods were attempted to calculate longitude before John Harrison's chronometers, made from 1730 - 1761. Which of the following was never part of a proposed solution at that time?

a. position of Jupiter's moons

b. gyroscopes

c. a wounded dog

d. sun's elevation above horizon

e. movement of moon

f. many cannons

(First trivia question of the first iDigBio Georeferncing Train-the-trainers Workshop, day 1, October 8th, 2012).