BENSON'S GREAT CLOCK.
The movement of this clock, next to that at Westminster, is the largest in the world, and, in point of quality of material and finish of workmanship, it is unequalled by any. The three main wheels are each two feet in diameter, and cast in the solid, of the very finest gun-metal, the teeth being afterwards cut by an engine made expressly for that purpose. The frame is of the best wrought-iron planed to a
Benson's Great Clock.—The Exterior.
Benson's Great Clock.—The Movement.
smooth surface, and by means of a contrivance, known to engineers as plumber blocks, any part of the mechanism may be removed without disturbing the remainder. The pendulum, which is self-compensating, is over 15 feet long, and vibrates or beats once in two seconds. The quarter chimes, which are struck on four bells, are a modification of those of S. Mary, Cambridge.
The great weights necessary to drive so large a clock, and which by the friction they would cause might prejudicially influence its performance, are in this case not allowed to act directly upon the pendulum, but are made to wind up a small auxiliary weight once every half-minute, and this weight imparts an exactly uniform impulse to the pendulum at each vibration. This arrangement, which is called the remontoir, is supplemented in this clock by a double lever escapement of a novel kind, in connection with that known as Graham's Dead Beat.