Today’s Gutenberg Gem is a neat little astronomy book, published in 1873 by Richard A. Proctor. It lists a number of half hour tours of the sky, each highlighting either a set of constellations or planets. It’s pretty brief, and certainly better modern guides exist, but it’s still a neat little thing to peruse through, for perspective if nothing else.

Half-hours with the Telescope by Richard A. Proctor – Project Gutenberg