It covers the theory behind clock movement and design, including the particulars of escapements, pendulums, balance wheels, and even the sheet music for popular chimes. The American striking clock, the 400-day clock, and the alarm clock receive special attention. The in-depth information, including explanations of clock repairing terminology and details on the tools, materials, and supplies that are needed for success, will benefit even skilled enthusiasts.
For my purposes of familiarizing myself with clockwork terminology and tools, this was very useful. The illustrations are particularly helpful. If I were actually planning to disassemble a clock and clean it, though, I think I'd want to read another book or check out YouTube videos--some of the instructions were a little difficult to follow without seeing the movements in action.