I decided to impulse the clock electromagnetically for a number of reasons. It was a fairly simple system, I could control the amount of impulse easily and I could use electromechanical logic in keeping with the precision clocks of the early 20th Century. (I was always more comfortable using relay logic). Makers of precision electromechanical clocks impulsed the pendulums in many ways. Fedchenko used electromagnetic impulsing below the pendulum bob very successfully. In an early experiment, Shortt also used under the bob mechanical impulsing but never achieved acceptable results. The later Shortt clocks mechanically impulsed the master clock more or less directly against the pendulum rod. I thought Riefler had one of the best systems.
He impulsed the pendulum through the suspension spring -
(ABOVE) Q1 on the test stand showing the relationship between the impulse coils and the pendulum rod. The glass bulb on the left is a capillary style sensitive vacuum gauge vernier.
(BELOW) A closeup of the experimental setup used to test the strength of the impulse given to the pendulum assembly. The field of the coils is reversed alternately.
(BELOW) The finished clock impulse mechanism showing the adjustable beat plate and adjustable impulse coils.
Q1 showing the impulse arm attached to the trunion holding the pendulum rod. A counterweight is fitted to the side opposite the impulse arm.