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[COPY.]
M. 5680/24.
SIR,
Admiralty,
S.W.1.
13th January, 1925.
With reference to your letter No. M. 5720/23 of 23rd April, 1923, and Admiralty Letter M. 645 of 17th May, 1923, regarding proposed tests of the Automatic Calling Device, I am commanded by My Lords Commissioners of the Admiralty to acquaint you, for the information of the Board of Trade, that the trials have now been concluded.
Two copies of a report are attached, and I am to state that My Lords have no objection to the publication of all or parts of the report or publication of a precis.
The Secretary,
I am, Sir,
Your obedient Servant,
(Signed) CHARLES WALKER.
Mercantile Marine Department,
Board of Trade,
S.W.1.
REPORT ON TESTS OF AUTOMATIC CALLING DEVICES.
1. In April, 1923, the Admiralty was asked by the Board of Trade to undertake experimental tests of automatic wire. less calling devices, with the object firstly of determining what in principle is the most satisfactory type of signal for such instruments and, secondly, of prescribing the condi- tions which apparatus for this purpose should satisfy in order that it may be passed as able to work satisfactorily under service conditions at sea.
2. The Admiralty agreed to carry out these tests, and a small technical committee, consisting of representatives of the Admiralty, General Post Office, Marconi Company and the Radio Communication Company, was formed to draw up a scheme of trial and to consider from time to time the results of the experiments.
3. At a preliminary meeting of the technical committee it was agreed that three sets of apparatus should be put under test, one being the General Post Office instrument designed to operate on a long dash of 15 seconds, the other two designed by the Wireless Companies operating on a signal consisting of three successive dashes of four seconds duration separated by one second intervals. It was agreed it was not necessary to consider any other possible signal.
4. A series of preliminary tests was carried out at the Signal School in October, 1923, but though some useful information was obtained it was considered that owing to the exceptionally bad conditions of heavy local interference no useful conclusions could be drawn from the tests.
5. It was agreed at a meeting of the Committee on 13th November that all three sets should be tested on a series of coasting voyages round the United Kingdom and after- wards in tropical waters.
6. The Clyde Shipping Company kindly lent their Steam- ship Rathlin for the purpose of the coasting voyage tests, and these were carried out on a number of voyages extending from 1st February to 31st March, 1924. The trials were carried out by Naval Ratings lent by the Ad- miralty. These men had no special training and the