Modern developments in precision timekeepers

Clocks of the gravity or pendulum type have for many years been used as precision timekeepers; but through recent refinements they have been made more accurate and reliable. Another development of the last decade is the use of the elasticity of quartz crystal oscillators as the restoring force in precision timekeepers; this has been made possible by the vacuum tube and associated electrical circuits. Both types of timekeepers are discussed in this article.