It's fascinating. The author has managed to write one of the best books on science and history I've ever read. He explains the development of different ideas, talks about the great astronomers of antiquity, and then provides practical examples and explains how the reader can duplicate the same experiments.

I learned how to read armillary spheres and astrolabes, how to determine the sun's angle with a sundial, how to determine the right ascension, declination, longitude and latitude of stars, how the ecliptic differs from the celestial horizon, determining true north, etc.