As a title, and bearing in mind that we are on a W/T Branch site, this looks in keeping, and it is obviously something to do with W/T....but the 'a' ?

Well, believe it or not this title means "WARNING TELEPHONE", and the 'telephone' bit, automatically made this piece of equipment a W/T Branch part of ship.  It has absolutely nothing to do with wireless telegraphy, neither for that matter with telephones, except that in the 1920's anything which had a microphone and an earpiece [the constituent parts of a telephone] were automatically a communicators piece of kit. The often huge amplifiers and control panels were always sited close to the main W/T office and sound powered telephone calls were made to the W/T office when adjustments were required to the main tannoy or to report defects on the system.

So what is a warning telephone. Simple. A ships tannoy system.

Over the tannoy came spoken orders, pipes, bugle calls, action station clangers/sirens, oh and yes, warnings.

Wa/T was a course syllabus entry for the W/T branch and ratings were examined for higher rate on the various fits in the Fleet.

It is not a subject which is even worthwhile describing, because although a very necessary part of a warship's organisation, a tannoy is a tannoy whether it is large or small and once you have heard one, you will know that it is usually very loud, very clear, an bloody annoying.

There were several Wa/T Sets [the 401, 402, 403 and 405] each one designed for a certain class of ship depending upon how many decks, how many compartments, and the size of the ships company.   Based on those criteria, the 401 [1927] was fitted in certain battleships, cruisers and aircraft carriers. It covered five groups of loudspeakers viz, officers quarters, engine room group, crew spaces, communication group and the armament group.  The system covered the VOICE facilities and the ALARM facilities. The 402, also a big ship system had more gadgets on it than on the 401. When the 403 was rolled-out  in 1930, it was considered suitable for fitting into many types of ships and being more modern in design and manufacture it required a cabinet half the size of the earlier fits. 

All Wa/T fits, including this, the Type 403, had a switch which when made, sent out a distinctive low tone to forewarn all,  that a tannoy broadcast  would be made shortly afterwards. With the Type 405 designed in 1936, this switch was not fitted, and as a HISTORY POINTER for you all, that was the start of the famous naval cry

" D'ye hear there"

a warning message sent out before each and every NON-ROUTINE use of the Tannoy System. The 405 also introduced automatic gain control [AGC] which with better power amplifiers and speakers, gave a more easy to listen to quality.  All ships in their turn were fitted with the Type 405 system.

These are some of the pictures from some of the systems.

Click to enlarge

Type 401

Click to enlarge

Type 403

Click to enlarge

Type 405 main gear. Half the size of the Type 401

Click to enlarge

Type 405

Now just in case you can't read what is on the inside of the cover to the TALK BOX of the Type 405, here is what it says


1 Move operating key to position 1 if call does not concern officers
or position 2 for General Calls.
1. Open alarm door
2. Speak across microphone and not directly towards it - mouth about 4 inches away.
Speak in loud conversational tone - do not shout.
When piping, pipe as close as possible to microphone.
Bugles should be at least 3 feet from and not directed straight towards the microphone.
2. Press alarm key in accordance with alarm signal required.
Lamp of output indicator should light and alarm note should be heard while alarm key is depressed.
3. Watch output indicator while speaking.
This should flicker and indicates that the set is working correctly.
If no flicker is seen the set should be assumed to be defective.
3. Do not touch operating key except to pass any subsequent verbal orders.
4. The alarm key is never to be operated without authority.
CAUTION  If another control position is seen or heard by the output indicator to 'break-in' while the control box is being used, the operating key must be
                    released immediately.


That's it. Now I will sound 'pipe down' so turn those light off and get your head down.......remember, you have the morning watch !