MARCONI SEAGRAPH / SEAVISA ECHO SOUINDERS
Wireless at sea - the first fifty years
ON THE LEFT IS THE MARCONI MARINE SEAGRAPH ECHO SOUNDER WITH ITS TRANSCEIVER SHOWN AT THE BOTTOM WITH ITS RECORDER UNIT ABOVE IT. TO THE RIGHT IS THE MARCONI SEAVISA AGAIN WITH THE TRANSCEIVER UNIT SHOWN BELOW THE VISUAL DEPTH RECORDER