Ford has beaten General Motors for the first time in nearly a century, in terms of number of US factory workers. Ford has 50,703 to GM's 50,300 or so.
Answers. Well, the simplest answer is that the astrolabe pretty well had to be used at night and could not be used in bad weather. The compass, which relys on the magnetic field of the Earth rather than a visualiztion of the stars, works at any time, and in any weather.
Because a compass needle points to the magnetic south pole and not the south pole you always hear about in Antartica. The same is true for a compass used in the northern hemisphere where the needle points to the magnetic north pole and not the north pole that the Earth rotates around.