Johnson Enlarging Timer
Johnsons of Hendon Ltd London England
2 ¼” face. Seconds and minutes hands. The time, up to 6 minutes, is set on the face of the clock which then runs down when the clock is started. A push-button starts the timer, a sliding switch controls the enlarger lamp for focusing, etc.
Construction: Black plastic body.
This is placed in the electric circuit of the enlarger and switches the enlarger on for the pre-set time.