Submarine Signal Company designed and built a number of different types of listening devices. Some of these, like the C-Tube, used "tubes" with rubber bulbs; and others, like the K-Tube used microphones mounted to frames.
The microphones, called "rats" because the bulb and tail somewhat resembled a rat, were produced in great numbers. This photo shows women testing micriophones at the Nahant facility.
Caption: "This picture shows where very nearly 15,000 rats were assembled. The microphone were first tested in another department and then as each operation was finished the microphones were tested and finally the completed product was given a matching test and packing test."
See this page for a shot of a K-Tube frame with "rats" installed.
Added recently:
- Photos of a kettle and headsets from SC 47, courtesy of Thomas Peloso.
- Photos of the Bluejacket chaser model kit, courtesy of Phil Lord
--Todd Woofenden, editor