|P.O. ENGINEERING DEPT.
Issue 1, Oct 1938
Clock No. 33
Clock No. 33, also known as the “Zenith Telephonometer,” is now obsolescent, but there are several which will continue to be used for
some years at exchanges where the timing of calls is necessary and “Clocks No.
44” are not fitted.
The clock has a small spring driven lever movement which is housed in a circular metal case,
2.5in. in diameter and 1in. in depth. It is fitted with a projecting lever for the purpose of starting, stopping and resetting. The action of resetting the hands of the clock rewinds the spring. The space required for fitting the clock is
3.25in. by 2in. by 1.5in. approximately.
3. The clock is fitted with electrical contacts, which provide for a signal to be given at 10 seconds before the expiration of 3, 6, 9 and 12 minutes. The signal duration is 10 seconds approximately. The clock will only operate for 12 minutes, after which period it must be reset.
Overall diameter - 3.5in.
Diameter of dial - 2in.
Depth (back to front) - 1in.
Two Clocks No. 33 are shown on this Trunk switchboard along with a