ATM TELEPHONES T.3904
CERTIFIED SURFACE TYPE MAGNETO TELEPHONE
Mines Department Certificate No. T/Tel/8. Wall Pattern
This Telephone is certified by the Mines Department as being intrinsically safe for surface use only, and is suitable for inter-connection with any approved magneto telephone system, the generator being fitted with a non-inductive shunt and the ringer shunted by an approved condenser. It is fitted with a hand microtelephone of the B.P.O. standard design, incorporating an approved design of transmitter.
T.3904 Wall Pattern Surface Type
Height 11in; width 11in; depth 6.5in;
Two-cell Battery Box for T.3903 Telephone (T.4651A)
Height 4.5in. width 3.75in. depth 2.5in.
Needs two T.2190 Dry Cells for T.3903 Telephone
Taken from the A.T.M. Mine Telephones and Signalling Equipment Book - April 1939
Last revised: October 06, 2012