F 7
Notice to Mariners.
1. The Marconi International Maritime Communication Company have issued the attached circular to their operators, and ship-masters are earnestly requested to co-operate in the forecasting and storm warning work of the Royal Observatory, Hongkong, by arranging for meteorological observations to be made in accordance with the programme given in the circular, and transmitted by the wireless operator without delay.
2. The accuracy and utility of the Observatory forecasts will increase in proportion to the number of ships co-operating, the accuracy of the observations, and the promptness with which they are despatched. In the interest of shipping, therefore, every master possessing a radio-telegraphic installation should send observations at the hours stated, viz., 6 a.m. and 2 p.m. of the 120th Meridian Time, and endeavour to make the service as efficient as possible.
3. It is requested that mercurial barometers should be used whenever possible, and that owners should co-operate by supplying their ships with at least one good mercurial barometer, of the Board of Trade pattern. Very few aneroid barometers are satisfactory. Generally speaking, the index error varies considerably from time to time, and is seldom constant throughout the scale. Moreover their readings are usually affected by changes of temperature though they are supposed to be compensated in this respect.
In every case the readings should be followed by the word "Mercury" if a mercurial barometer is read, or "Aneroid" if an aneroid is read.
4. It is very important that a few readings (at least four) of the ship's barometer (the barometer used for the wireless messages) should be taken in Hongkong and forwarded to the Observatory, in order that the correction to the Observatory Standard may be obtained; otherwise the barometer readings are useless. It is also very important that the readings should be exactly as read off, without any correction whatever, except in the case of ships which have not sent comparison observations to the Observatory. Such ships should correct the readings for index error, and reduce them to 32° Fahrenheit, sea level, and gravity at 45° latitude; using the best index error available and adding the word “corrected”.
26th September, 1919.
T. F. CLAXTON,
Director.
THE MARCONI INTERNATIONAL MARINE COMMUNICATION COMPANY, LIMITED.
CIRCULAR No. 364.
Operators employed on board ships trading to the Far East will note that arrangements have been made to transmit from the Cape d'Aguilar (Hongkong) Radiotelegraph Station to ships at sea a summary of meteorological conditions and weather forecasts. In return, ships will forward meteorological observations through the Cape d'Aguilar Station to the Royal Observatory, Hongkong.