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.
A compass, Lou, has a magnetic needle which, when the compass is held level, floats freely over the center of the compass rose. The needle rotates until one end (the black end in this case) points to magnetic north and the other end (the red) points to magnetic south!.