Glossary

Escape mechanism — a pivotal piece that controls the speed of the energy released by the weights and transmits it to the gears in a measured way to keep time.

Angles, pitches, teeth — ‘teeth’ are the bits that stick out on a gear or cog. The ‘pitch’ is the difference between each tooth. The ‘angle’ is the angle of the tooth itself, and they all need to be the same so they can mesh in with each other.

Jig — a piece of equipment that you make to hold something, so that you can press it, drill holes in it, or line it up with something else that you are going to do.

Spindle — also called the ‘arbor’, is a rounded shaft on which a wheel or gear is mounted in order to spin freely.

Weights — weighted tubes filled with lead that drive energy to the escape wheel. The pull of the weights makes the escape wheel turn, the energy of this travelling through all the other wheels or gears in turn and ending in the hands turning on the dial.

Pendulums — these were added to clocks from about the mid-17th century and made clocks more accurate. In a clock such as Dad’s, which has an anchor escapement, a ‘bob’ can be slid up and or down on the rod to affect the swing of the pendulum, thereby increasing or decreasing the swing and therefore the speed of the hands. (Finally, a way to slow time down!)

Anchor escapement — this is the C-shaped piece that makes the clock tock and tick. It rocks back and forth, engaging with the teeth of the escape wheel by the energy that comes through a lever attached to the pendulum. It was invented around 1670 by Robert Hooke or William Clement and was first used in longcase clocks.