"Sub Sig" echo sounder type 301/642 recorder
'Sub Sig' echo sounder type 301/642 recorder, serial no.201, by S G Brown Limited and Submarine Signal Co. (London) Limited, Watford, Hertfordshire, England, 1954-1963.
'Sub Sig' echo sounder type 301/642 recorder, serial no.201, by S G Brown Limited and Submarine Signal Co. (London) Limited, Watford, Hertfordshire, England, 1954-1963.