This handbook presents both theoretical and practical data pertaining to design methods and procedures for using timing systems and devices. The subjects covered are precision reference timers, electronic timers, mechanical timers, pyrotechnic timers, flueric timers, and a few others. Prepared as an aid to military designers, this handbook should also be of benefit to scientists and engineers engaged in other related research and development programs or who have the responsibility for the planning and interpretation of experiments and tests concerning the performance of materiel related to timers.