Designed by George Goodenow, this pendulum is BEARING BALANCED. That means the pendulum chain rotates and swivels on a bearing that is inserted into the top cap(chamber cover). This results in a balanced swing that keeps the pendulum point, or bob, always aligned with the chain while swinging . This movement provides an instant and sensitive response. This alignment is excellent when using charts, always pointing in harmony with the arc of the swinging pendulum.
The chain is about 5 1/2 inches long. The pendulum bob is about 2 inches long, 9/16 inches in diameter, and weighs 24 grams. This would be considered a medium weight metal pendulum.
The chamber is about 7 mm (9/32″) diameter and 5 mm (3/8″) high. More space is available in the chamber cap. The BBMM1 has a smaller chamber than the BBMAUS.
The pendulum bob is stainless steel. The chain is vibration-free nickel plated brass.