From the Boston Children's Museum, detailed instructions for building models of sundials, water clocks, and mechanical clocks. Using a variety of common materials and a good deal of ingenuity--the word has the same root as ""engineer""--the author and illustrator together show how to make a variety of both primitive and more modern timepieces. Plastic soda bottles, plastic cups, ballpoint-pen barrels, spools, and other household materials are pressed into service to make water clocks, escapements, and other mechanisms. The strength of the book is the models, some of which look easy to build, others more difficult yet possible; but the lack of a scientific framework to put around the experiments is a weakness. The principles behind what's being demonstrated or measured are not clear; and even when a scientific idea could easily be inserted--such as the period of a pendulum depending only on length, not weight--the opportunity is missed. The result is a book that could leave a curious afterimage of the ancient Chinese or Egyptians carefully timing drops of water with their watches to insure uniformity. Useful chiefly as a supplement to more formal instruction.