<span>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.</span>
Get more into real life situations. For example something that will make this decade more interested. Instead of something for 1875 that everyone will get bored of.
