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"Victorian Era Visual Signalling Instruments"

"Black Watch, 42nd Royal Highland Regiment Signalling Unit, c. 1898"

by Neal McEwen, K5RW

k5rw@telegraph-office.com

Copyright © 2000 - 2002,  Neal McEwen

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Landline telegraphy was a mature and widely used technology by the armies of the world at the turn of the 20th century.  However, military units in the field needed a way to signal other units where there were no wires.  The photo to the right, gives us insight into Victorian era visual signalling technology and the types of signalling instruments used before the deployment of wireless telegraphy, where wireless telegraphy was not available or where wireless telegraphy was not secure.

This high quality albumen photograph is from the personal photo album of William Henry Jenkins, who was a Sergeant in the Black Watch.  Jenkins was born in England in the 1870s.  He served for a time as part of Queen Victoria's bodyguard.  In 1905, he and his family moved to Quebec Canada.  The photo was obtained indirectly from the great-granddaughter of Jenkins.

With the aide of my strongest reading glasses and a magnifying glass I was able to determine quite a bit from this photo.  Most of the soldiers in the photo have a crossed flags patch on their shirt sleeve, denoting a signalling unit.  Signallers were trained in 'flag waving,' semaphore, heliograph and lamp signalling and accompanied various staffs and units of the British Army.  In time of war they would set up fixed or moving stations based on the needs of communication with points of strategic or tactical importance.   A typical applications of a visual signalling would be for headquarters to communicate with a detached unit.  Another application would be coordination of advancing parallel units.  In some cases visual signalling was used to augment or replace telegraphic communication.  When it was not practical to extend telegraph lines and equipment to the front, telegraphers and signallers worked together to form a communications chain.

Click on the photo for a larger image of these handsome and dapper lads and their signalling instruments.  Click on each of the links below for detail of each visual signalling instrument from the photo or to see a reference to the instruments.

The soldier on the far left is holding a Mk IV heliograph.  The heliograph is an instrument that uses the suns rays for signalling.  Heliographs were first used by the British Army in India in the 1870s.  The first use of the heliograph in war seems to be in the Zulu war of 1877 to 1879.

The heliograph came with two mirrors.  When the sun is in front of the heliograph, a single mirror is used to reflect the suns rays to the distant station..  When the sun is behind the heliograph, the second mirror is used to reflect the suns rays into the first mirror.

British heliographs did not have a shutter in front of the mirror.  A movable mirror, controlled by a mechanical linkage to a telegraph key, was used to direct the sun's rays to the distant station.  The constant movement of the mirror tended to throw the mirror out of adjustment, causing loss of transmission.  For a detailed explanation of the heliograph's physics and operation, see Tom Barker's Heliograph.

The advantages of the heliograph are long range (30 miles or more), portability and rapidity of operation, approximately five to twelve words per minute.  The major disadvantage of the heliograph is the need for the presence of the sun.  The heliograph can be used with moon light, but at a very reduced range.    Long range used required the two stations be on high ground to overcome the earth's curvature and required the use of a marine telescope.  Interception by the enemy was not possible unless they were in the line of site between the two stations.

Typically the heliograph was  operated by three men. In the case of the sending station,  the "caller" handled the message form and called out the letters to "sender" who operated the heliograph.  The "answer reader" watched the receiving station for acknowledgment of a word.  In the case of the receiving station, the "reader" with telescope, read each letter and called them out to the "writer" who wrote them down on a message form.  The "answerer" acknowledged receipt of a word.

The soldier on the far right is holding a Lime Light Signalling Lamp.  The lamp creates an intense light by passing a jet  of oxygen through an alcohol lamp and onto a pencil of lime, raising the the lime to white hot.  Notice the hose running to a bag on the ground.  This oxygen reservoir, made of leather, could contain three and one half cubic feet of gas capable of sustaining the flame for 40 minutes.  Pressure from the bag was produced by piling earth on top of it.  The oxygen is prepared ahead of time by heating chlorate of potash and granulated binoxide of manganese on an open wood fire in a retort connected to the gas bag through a 'wash bottle' to purify the oxygen.  Several bags could be filled at one time.  The lamp was keying by means of a shutter in front a lens that focused the flame.  The lamp was sighted by peering through a small diameter tube resting on the alcohol reservoir.

In addition to the Lime Light Signalling Lamp, the Begbie Lamp was used.  It was a kerosene lamp with a lens to focus the light over a great distance.  A shutter is internal to the lamp, between the flame and the lens.  The shutter was was worked by a button on the outside of the lamp.  A British Army training manual states, "The shutter is worked in the same manner as the dummy key.  Care should be taken that the shutter is fully opened for dots as well as dashes.  Some signallers have a tendency to cut the dots too short, but this should be carefully guarded against."

The signalling lamp came in two sizes, standard,  used in signal service, and the large as shown in the Black Watch photo for 'training schools and special purposes.'  Both instruments are shown in the British Army 'Training Manual - Signalling 1907.'  The signalling lamp (or flash lantern as it was called by the U. S. Army Signal Corps) is most useful at night with a throughput about that of the heliograph.  The disadvantages of the signalling lamp are the presence of rain, fog or moonlight.

In the middle of the photograph, on the ground, there is a telescope..  The telescope is used to observe signalling stations from greater distances than can be seen by the naked eye..  The telescope is shown in a British Army training manual as the Mark II Signalling Telescope.  The telescope not only magnifies the desired object, but also everything else in the field of view.  At high magnifications, the distant object may be more difficult to see because of the magnification of dust and moisture particles.  The telescope has three draws and has a magnifying power of 15 or 30 depending on the lens choice nearest the eye.  The low power lens is provided for general use and the high power lens is provided for use on clear days.

Also on the ground are two small hand lamps.  I have not yet identified the two small lamps, although they are somewhat similar to Cadet Signalling Lamps shown in an advertisement taken from an Imperial Army book dated 1915.

Several of the soldiers, including the two in the front row at the left and right, have hand flags, used in semaphore signalling.  The flags are white with a small diagonal stripe.  The white flag indicates use with a dark background such as a forest.  Dark flags are used with a light background.  With the semaphore system it is important to keep the flags moving so as to keep them unfurled and easier to see at a distance.

Semaphore signalling is done with two flags and is advantageous due to the portability of the flags and the rapid manner in which a station can be set up.  However, semaphore signalling is not practical over long distances, at night or through dust and smoke.  The maximum speed attainable with semaphore signalling is five or six words per minute.  Semaphore signalling traces its ancestry to the stationary aerial telegraphs implemented in France in the late 18th century by Claude Chappe.  British Army semaphore signalling is an adaptation of the British Royal Navy's mechanical semaphore system.  A page from 'Brown's Signalling,' 1916 show a sample of the British semaphore hand flag code.

There was also a single flag system called 'flag waving.'  Two different sized flags were used.  A three foot square flag on five and one half foot pole could be used for distance of five to seven miles.  A two foot square flag on a three and one half pole could be used for distances of three to four miles.  When sending messages, the flag man would keep the flag moving in a rapid motion to keep the flag unfurled and thus more visible.  Small flags were easier to handle than the large flags and thus could be used for faster transmission of messages.

The flag was moved through a short arc for a dot and a long arc for a dash.  The resting position was 25 degrees from the vertical over the head of the flag man.  The flag man could work from either right to left or left to right depending on convenience and the direction of the wind.  A dot was made by swinging the flag from the resting position to 25 degrees from the vertical in the opposite direction and returning to the resting position without a pause.  A dash was made by swinging the flag from the resting position to 115 degrees from the vertical in the opposite direction and returning to the resting position with a pause in the down position.

The Continental Morse code, later called the International Morse Code, was used with the heliograph, the signalling lamp and single flag signalling.  Signallers learned Continental Morse on 'dummy' keys.  These 'dummy' keys resemble and ordinary telegraph key except there are no connections.  It makes the sound of a telegraph sounder.   The instructor would call out a letter and then send it on the 'dummy' key; the student learned the sound of the letter and wrote them in block capital letters.  It is interesting to note that instructors used 'toc,' 'ack,' 'beer,' 'emma,' 'esses,' 'pip' and 'vic' instead of 'T,' 'A', 'B', 'M', 'S', 'P' and 'V' when calling out letters; this was done to avoid confusion with similar sounding letters such as T and E or A and H for example.

A 'dummy' key is shown to the right.  Click for a full size photo.  This particular key was made by Houghton - Butcher Mfg. in 1917, and is is labeled "Key, Dummy, Signallers".  (This particular key was used by the 3rd and 4th battalion, Royal West Sussex Regiment.)  A British Army training manual states, "By obtaining a complete mastery in sending on the dummy key, much time will be save in acquiring proficiency in sending, both on the heliographs and lamps."  Students were not allowed to practice on the heliograph until they had mastered the 'dummy' key.

Each soldier in a signaller's unit was tested annually for proficiency in all of the visual signalling methods, heliograph, single flag, lamp and semaphore.  The test was to send and receive a message of 200 letters, without the aide of telescope or binoculars, at a distance not less than 500 yards.  For heliograph, small flag  and lamp, the time allowed was six minutes.  For semaphore the time allowed was five minutes.

With the deployment of wireless in the very early 20th century, signalling with heliographs, lamps and semaphores took a diminished role in military communications.  However, wireless could easily be intercepted by the enemy.  So visual signalling was advantageous when the enemy was over the horizon or out of the line of site.  Visual signalling equipment continued to be used through W.W.II and beyond.  Afghan resistance fighters used the heliograph during the Soviet invasion of their country.

Shortly after this photo was made, some units of the Black Watch were serving in the Anglo-Boer War (1899-1902) in South Africa.  Considerable use was made of the heliograph by both sides during the this war.  In addition to tactical use, it was employed by the British to replace telegraph lines cut by Boer commandos.

The sunny climate and clear skies of South Africa were ideal for the heliograph; a five inch mirror could be used to 50 miles and a ten inch mirror to 100 miles.  Rudyard Kipling makes us aware of the heliograph's wide use with references to the heliograph in three poems from "Service Songs, South African War."

Visual signalling was the primary means of communication with forward units during the Boer War.  However, the telegraph was used to communicate from headquarters to field units to the division level.  The submarine telegraph was used to communicate with the British government.  By the end of the Boer War, British Army telegraphers numbered 2,500 and had handled 13.5 million messages.

It is interesting to note that the Anglo-Boer war was the first instance of wireless telegraphy being used in war.  The British had Marconi built instruments and the Boers had instruments made by Telefunken.  In the fall of 1899, the Army and six engineers from Marconi, including Charles S. Franklin, later famous for his understanding and application of short waves for Marconi, arrived in South Africa with five portable wireless stations.  Due the the infancy of the technology and the severe conditions under which they were used, neither side was able to make practical use of their wireless sets.  Lightning effected the coherer and poor ground conductivity limited the transmitter range.  Dust storms also played havoc with the equipment.  In February of 1900, the British Army abandoned the use of wireless in the Ango-Boer war.

The Anglo-Boer War was the last major conflict to make extensive of the heliograph.  The worlds armies were phasing out the heliograph after World War One.  The Canadian Army continued to issue heliographs through World War Two.

All of the soldiers in the photograph, except the one in the dark tunic, is carrying a rifle.  It is not obvious because the rifle sling is white, the same color as their tunics.  The Black Watch was formed in the early 18th century to police the highlands of Scotland.  It is the oldest and best known of the highland regiments.  It remains a part of the British Army to this day.  You may visit the official Black Watch Home Page for further information.



Bibliography

"Anglo-Boer War set the stage for military wireless telegraphy." http://www.institute.ieee.org/INST/aug95/wireless.html

"Back Watch Home Page." http://www.army.mod.uk/army/organise/infan/blackwat/index.htm

Beauchamp, K. History of Telegraphy. IEE History of Technology Series 26, IEE, London, 2001.

Brown, James. Brown's Signalling: How to Learn the Commercial Code and All Other Forms of Signalling. James Brown & Son, Glasgow, 1916.

Burlingame, Lynn. email to Neal McEwen 13 November 2000.

Coe, Lewis. Great Days of the Heliograph. Lewis Coe, Crown Point, Indiana, 1987.

Davies, Wyn. Email to Neal McEwen, 15 November 2000. scanned image from an Imperial Army Series book dated 1915.

Dunlap, O. E. Radio's 100 Men of Science. Book for Libraries Press, New York, 1944

de Vries, L. The Book of Telecommunication. MacMillan, New York, 1962.

"Fact File: The Black Watch (Royal Highland Regiment)"  http://www-saw.arts.ed.ac.uk/army/regiments/blackwatch.html

"First World War Visual Signalling" http://www.royalsignals.army.org.uk  Royal Corps of Signals Museum Home Page

"Heliograph." http://www.warlinks.com/pages/heliograph.html

Nilski, Zyg. Email to Neal McEwen, 14 November 2000. quoting from Training Manual -- Signalling 1907.

Signal Book - United Sates Army 1912.  Government Printing Office, Washington, 1912.

Training Manual -- Signalling, 1907, General Staff, War Office, London, 1907


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Neal McEwen, k5rw@telegraph-office.com