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As signallers we also trained to use semaphore, but like flag signalling by morse it was never used. Occasionally it helped to pass instructions between signallers.
Semaphore has an interesting history. Designed by the Chappe brothers in France during the late 18th century, it was reputed to have been used to carry messages between units of Napoleon's army.
The signaller holds the flags arms extended in various positions to signal different letters and figures. The signal letter 'J' also indicates 'alphabetical letters follow'. There are special flag positions to indicate 'numerical signals follow' and an 'erase' signal. |
There were two other forms of visual signalling. Sending morse by signalling lamp and by heliograph. An Infantry Battalion Signals Platoon had four 'Lamps Signalling Daylight Short Range', and we were trained to use them. A clear line of sight was necessary between sender and receiver and by day the lamp signals could be read at a distance of about two miles; but by night, six miles. These ranges of operation increased two-fold when signals were read by telescope and we had a number of these in our Signals Stores. However, weather was always a factor that could affect distances. |
As well as having a ground spike the lamp was generally used on a tripod, being equipped with morse key and powered by eight 1·5v batteries. The lamp itself had a glass front, fitted with a 10v bulb seated on a spring with a glass reflector at the rear. The lamp had a sighting tube with a small aperture at one end and crossed slots at the other used for alignment purposes. Three coloured disks were available for use according to conditions; amber when fog, green for snow conditions, red to either distinguish the identity of your station or to make your signals distinctive during artillery bombardment. There was also a perforated screen that could be used to cut down the spread of the beam during darkness. |
 Courtesy www.museumoftechnology.org.uk |
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Each signalling lamp required testing for true alignment. This
was done by aligning the lamp beam about 20 feet away from a flat surface and where the light beam hit the surface it was marked by an 'X' 2¼ inches from the centre of the beam. Looking through the sighting tube, the 'X' should be in the centre of the cross slots. If it was not, the amount of the deviation had to be recorded on a diagram inside the lid of the box so the degree of error could be allowed when aligning the lamp for signalling to the distant station. The operator had to look through the circular aperture and move the lamp until the distant station was in the centre of the cross slots or move the lamp taking account of its alignment problems. |
Courtesy www.museumoftechnology.org.uk |
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The Signals Platoon had four 'Heliographs 5-inch Mark V' as part of our signalling repertoire. A British invention, it was used by the Army in the Far East and our Signals Sergeant told us the heliograph 'flashed' the football results around the various Army units on a Saturday night in the years between the Wars. It can be used long distances; up to 120 miles in the Far East, but about 40 to 50 miles in this country. I recall the special excitement of using the heliograph during a training session on the golf links overlooking the Firth of Forth in the early 1940s, when with the aid of a bright moon the heliograph worked beautifully and the signals could be read clearly.
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| The heliograph has a signalling mirror with an unsilvered spot in its centre and a siting arm with a jointed sighing rod with movable vanes. There is also a duplex mirror held in 'U' arms with a butterfly screw. The base has a morse key. |
The position of the signalling mirror has to be positioned to reflect the light from the signalling mirror on to the distant station.
Although it is not possible to see whether the reflected light is on to the distant station, there is a sighting mark on a vane which can be brought into alignment with the centre of the signalling mirror and
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the distant station. The small unsilvered spot in the centre of the signalling mirror causes a small shadow-spot to be thrown on to the vane and the signaller can accurately site on to the distant station. The first rough sketch (left) from my signal notes of 1940 indicate the two positions of the signalling mirror: when perdendicular it is reflecting signals to the distant station; when the key is released the suns rays are deflected away from the station. |
(1) Shows when the angle between the sun and the heliograph and distant station is at right angles or less, the sighting rod is used in conjuction with the signalling mirror; the angle of the mirror facing
the bi-section of the angle
between the sun and the distant station. |
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(2) As the sun appears to move across the sky, the tangent screw gives you lateral change and the collar allows change of elevation. |
(3) If over 90 degrees the duplex mirror is brought into use. The signalling mirror faces into the sun's rays which are then reflected on to the duplex mirror and onwards to the distant station. |
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When searching for a distant station, the heliograph has to send a series of dashes which are traversed over an area, doing this slowly by turning the elevation collar or the tangent screw which moves the signalling mirror in a systematic way to cover every part of the ark. When the distant station locates your flashing signals, it will align on to you.
Heliograph and Signalling Lamp were not a secure means of sending messages as the heliograph beam had a lateral dispersion of 16 yards at one mile, the Signal Lamp 40 yards at the same distance, and messages could be intercepted by the enemy. There was the added disadvantage that light beams attracted enemy fire on the transmitting station. |
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Page Links ~ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
11, 12, 13, 14, 15, 16,
17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27
28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46 Index |
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