The Royal Signals .. Heliograph

Recording Signalling Methods, Technology, Equipment & History for Posterity

The following is a compilation of many different sources and information by Petra, some she found from on-line web sites, some from books, some translations from German sources and a lot is simply written by herself, including the noticeably "odd" inclusion of her very twisted humour from which everyone distances themselves! (even Petra) That said you can hopefully still learn a lot and have fun? So anyone who is unhappy with the content of this free newsletter or datasheet can ask for a full refund under our standard Policy. A copy of the policy can be purchased for three hundred pounds sterling including P&P from Petra directly.

Royal Signals Datasheet No. 2. The Heliograph Last revised April 2003

Communication via Heliograph using "Morse"

Figure 1. Head Detail and full Heliograph

Figure 1. Head Detail and full Heliograph (Mk
5 Mance model)

The original Instructions scanned, OCR'ed and restored, from a Signalling handbook (1905) are also to be found linked to at the end of this document!   Link to 1905 Signalling Document


The heliograph provided a very mobile element in the British Signal Service and was light, quick to set up and Cheap to make. In heliography, a mirror is used to flash light in "Morse" code. Using this method, eight to sixteen words could be transmitted per minute and the equipment was relatively cheap and easy to manufacture - in the absence of anything else, a simple mirror would suffice - and a 'crew' of only one trained person was required. signalling ranges varied, depending upon the size of the reflector. For example, a 5 inch reflector had a signalling distance of some 50 miles (80 km), whilst the 9 or 12 inch models had a range of up to 80 miles (130 km). Indeed, in India, signalling distances of over 100 miles (160 km) had been recorded and it is interesting to note that, at least until 1975, the Pakistan Army continued to use the heliograph, and that in 2001 during the invasion of Afghanistan the Coalition forces found that the Taliban and other regional forces still used them.

But let us first look at the history! From an Encyclopaedia of 1895 came the following definition:

HELIOGRAPH (from Gr. Helios, sun, and graphos to write) an instrument for reflecting the rays of the sun (or the light obtained from any other source) over a considerable distance. Its main application is in military signalling. A similar instrument to the heliotrope, used principally for defining distant points in geodetic surveys, such as in the triangulation of India, and in the verification of the African arc of the meridian. It is necessary to distinguish the method of signalling termed heliography from the new photographic process of the same name.

Petra's note: The new Science of Photography was being called Heliography from "Drawing (Graphic) with Sun (Helios) or Sunlight (Photo)" The confusion about the name Heliograph was caused by a Frenchman (Who else?), and inventor, called Joseph Nicephore Niepce, who produced the first photograph through a process he calls heliography or sun drawing in 1816, but the images faded within days. Later he together with Louis Jacques Mandé Daguerre made stable pictures on glass what was called 'Daguerreotypes' and in 1829 Niépce and Daguerre form a 10 year partnership to develop photography which while not subject of this newsletter has been able to entertain British troops since WW1 and their purchase of French Daguerreotype's of young Mademoiselles with little or no clothing ever since! Daguerreotype had insisted that they take their clothes off since it improved the (photographic-) Exposure by needing less materials for the sun to paint!!! The Heliographers in the army were appalled to be associated with pornography under the name Heliography and insisted on their cut of the profits or at least a set of negatives for their own use, but failure to get it made them go to war in France and the French under military force duly changed the name to Daguerreotype!!! (Sorry! one of Petra's funny looks at History and a slight bending of facts!)

By an odd twist of fate, it was Samuel Finley Breese Morse ("Inventor" of the Morse code) who introduced Daguerre's process of photography, into America.

Back to some real history. Then it shows us that Heliography (using polished shields to reflect the sun) was used in antiquity, by the Romans and also used by the Athenian's to signal from ship to shore, between ships and also between ground forces although they did not have any records of trying any ground to air communications with their air-force! (Another poor Petra joke!) as can be read in Xenophon's Hellenica written in ca. BC 405.

There is also a brief reference to a method of signalling in the biography of Tiberius, Claudius Nero Caesar Augustus (Born 42 BC - and Emperor from year10 AD till his death in 37 AD) written by Suetonius, in Book III of The Twelve Caesars.

"For nearly ten years during the reign of the wise but unpopular emperor Tiberius, Rome was ruled from the island of Capri. Each day he sent orders to the mainland by a type of "heliograph" which transmitted the sun's rays by means of a mirror of polished metal."

but it is unclear if intelligent signals were sent by this method, or simply a check to see that outer positions were still in good state?

A first clear description of a heliographic signalling method was published in 1292 by the English author Roger Bako (often spelled Bacon, 1214-1292), in a work called Opus Majus. There is, however, no record that it was actually used by the British in this period, who were particularly adept at sending messengers on foot or horse and covering the "last (qtr-)mile" (to put it into modern telecom terms) if necessary by use of a longbow and arrow. Then the British missed one thing needed for good Heliography, the Sun (or the Daily Mirror, The Telegraph, etc. Interesting to note how many papers have names that can be tenuously connected with communications or for that matter "News!")

Richard Hennig quoted a description of a heliograph from the sixteenth century author Khevenhiller. In Annales Ferdinandei, Khevenhiller described a device that had supposedly been used during the siege of a Hungarian fortress in 1598

". with an art, as described by an Englishman, consisting of two mirrors and a magnet [a compass?], with which one can, at a distance of many miles, give signals to each other in moon-light."

Hennig questions the feasibility of the method. Yet, if the "magnet" was really a compass, it could have been used by the two correspondents to locate each other, before their signalling began. On a clear night, the light of the moon can be reflected as easily as the light of the sun during a clear day, so the device would probably have worked. Then later Modern High Quality Mirrors used in the British Military signalling were definitely capable of Lunargraphy which is the name I give it when a Heliographer goes Moonlighting!

The design of a modern mechanically-set (on tripod and adjustable frame) heliographic device was not reliably documented until 1810.

Carl Friedrich Gauss (1777 - 1855)

Professor Carl Friedrich Gauss of Göttingen, Germany, invented a device in 1810 to direct a controlled beam of sunlight to a distant station. It included "silvered and half-silvered mirrors" which are then fixed at right angles to each other. The operator looked in the half-silvered mirror at the distant station. He then turned both mirrors so the sun's image (reflected faintly from the plain surface of the half-silvered mirror) was superimposed over the distant station, automatically directing the beam from the silvered mirror in the same direction.

Though the device built by Gauss was meant to be used for geodetic survey work, which is probably where the British Engineers first put it to use, they soon discovered it could (in the hands of a skilled operator be used to signal as good as, if not better than flagging alone! Indeed it would later be used extensively by both the British and the American armies as a so-called "wireless" field telegraph, albeit with different versions of Morse codes between them.

"Early in the nineteenth century, Gauss, a German mathematician, had discovered the tremendous potential of the sun's rays reflected from a plane mirror. Through experiments he was able to demonstrate that even a small mirror one inch square could send flashes that could be seen over a distance of seven miles. The silvered glass mirror, invented in 1840 by Justin Liebeg, paved the way for the heliograph. (...)

We know Gauss from a different endeavour perhaps? De-gausing a TV or computer screen. Or the term Gauss from Magnetism, then this was the same person and mathematician who made such discoveries and permutations. His original name was Johann Friedrich Carl Gauss, a German mathematician, generally regarded as one of the greatest mathematicians of all time for his contributions to number theory, geometry, probability theory, geodesy, planetary astronomy, the theory of functions, and potential theory (including said electromagnetism). He was also honoured on the back of the German Ten Mark Note and numerous Stamps despite being guilty of "mathematical child-abuse" in schools worldwide due to his Fundamental Theorem of Algebra.

Figure 2. Ten Deutsche Mark Note with Carl Friedrich Gauss

Figure 2.
Ten Deutsche Mark Note with Carl Friedrich Gauss

Sir Henry Christopher Mance (1840 - 1926)

In 1869 the English electrical engineer Henry C. Mance adapted Gauss's design by adding a movable mirror that could be used to signal Morse code. By adding stops to set the on target and of target positions of the mirror tilt. But the movement was still by hand and due to the vigour's of movement the device needed constant resetting to re-establish the line of sight started with. It did not take him long to add a Telegraph key and linkage similar to one being designed by Babbage and by 1875 he had developed the heliograph or sun telegraph (Royal Society Letter No. 7/36). So the original hand keyed model was therefore invented by Sir Henry C. Mance, at that time in Karachi, Bombay. Who made a patent application at US Patent Office in February, 1876.

Sir Henry C. Mance, C.I.E. Went on to become Director of the West African Telegraph Company and a chairman for the Electric Construction Company.

Meanwhile in the UK an engineer who long after his death was determined to be the father of modern computing took a keen interest in mathematics, statistics, railways and the unification of England, Wales and Scotland by railways. Who had invented the standard railway Gauge, to ensure that when the different railway companies met up they would be compatible! and invented the GMT standard-time for the entire UK to ensure the trains all ran "late" to the same time and timetable, and due to his interest in Surveying and calculation of triangulation data, he took an active part in designing the Heliograph essentially coupling the Heliotrope with a vertically depressed Morse key to overcome pushing or pulling the set of course, and mechanical adjustment mechanism to allow it to send code faster and be readjusted for sun deviation on a predictable basis got involved with signalling. But Babbage was more interested in adding clockwork to send automated code, and/or make precise corrective adjustments for the movement of the sun, which while later used in telescopes for stargazing photos using long-time exposure, would have been too costly, complex (to set up) and fragile for practical military use. Odd that Heliography, Mathematics and Photography keep crossing paths in so many different cases.

Charles Babbage (1791 - 1871)

Born December 26, 1791 in Teignmouth, Devonshire UK, Died 1871, London; Known to many as the true "Father of Computing" for his contributions to the basic design of the computer through his Analytical machine. His previous Difference Engine was a special purpose device intended for the production of tables including accurate trigonometry and Log tables needed by the ordinance and military surveyors.

His inventions list included; The cowcatcher, dynamometer, standard railroad gauge, uniform postal rates, occulting lights for lighthouses, Greenwich time signals, heliograph, ophthalmoscope. He also had an interest in ciphers and lock-picking, but he was not popular with the public, then he abhorred street musicians and campaigned for their prohibition from the streets.

In 1851 Charles Babbage, the builder of the so-called analytical engine, a precursor of the modern digital computer, invented a "light-flashing machine," which he named an occulting telegraph. This is how Babbage described it.

"I then, by means of a small piece of clock-work and a bright lamp, made a numerical system of occultation, by which any number might be transmitted to all those within sight of the source of light."

I think the purpose of these occulting telegraphs were to send a form of automatic "marker codes" and was later adopted by lighthouses to send a Morse letter to give their location/ID. Then constant light was OK when trying to identify one station, but when as in the case of triangulation many teams were being deployed, to help find and identify the two you needed for triangulation was very important, Besides Babbage was a keen proponent of the mapping of countries and the resulting processing of mathematical statistics.

Babbage also described another "sun-flashing" machine, which resembles Gauss's design more closely. Babbage had worked a lot with mechanics and levers, linkages and the like, and so it was no surprise when he added a Morse key, and an counter-threaded adjustment screw that when turned at regular periods would keep the device compensated for the movement of the sun.

For More On Babbage Click

Heliographs and the American Army

The American Army made an extensive use of heliographs in the 1880s, in combination with the so-called real Morse code. It is unclear if they were based on Babbage's proposal or Henry Mance's but the British Army however decided that Mance's was the better design. It did however play a major part in communications between forts, outpost and during the building of the railways.

The American Heliographs for some strange reason had square mirrors, but the shape of the mirror still created a round projection beam, then the sun remained round even on the other side of the big pond! A larger mirror was sometimes preferred over the "right sized" one by the operators, if they could get away with it, who would have less tracking adjustments to make to keep the target within beam as the sun traversed the sky. But there was a rule as to which size was for what distance. As a "rule of thumb" the range of a heliograph is ten miles per inch of the mirror's diameter.

Therefore, a 5" mirror, whether round or square, would have a range of about 50 miles, the 1.8" mirror of some more modern handheld equipments, work for about 18 miles.

In 1886 heliographs were used by General Nelson Miles, in his battles with native Americans in Arizona. He built a total of 27 signalling stations, 40 to 50 km (25 to 30 miles) apart. Between 1 May 1886 and 30 September 1886 a total of 2,276 messages with 80,012 words were transmitted over this network. The heliograph is said to have averaged some 16 words per minute.

Differences between the Heliograph and the Heliotrope

The heliotrope and theodolite were in their principles identical, and based on Gauss's 1810 invention of the Heliostat/Sextant, then Gauss had calculated a way to predict the angular height of the sun for every location on the earth at every time of day and vice-versa and so revolutionised both seafaring and mapmaking at one go and also improved communications!

The only significant difference between the Heliograph and the Heliotrope was that the latter was set so as "not" to reflect sunlight to the distant station unless it were sending a part of a code (dot or dash!), whereas the other was originally intended to be set to constantly attract the attention of the distant station to the location of the survey team by continuously reflecting light to such station. Indeed the Heliotrope was used before such surveys for only such purpose and the viewer attracted by the light would then spy out the flagman and read the code off the flag signals. However it did not take long to see that it could be possible for the mirror (with some mechanical appendages) to tip up and down and accurately send signals in place of the flags. From an 1858 report of the previously conducted "Trigonometrical Survey of India" it was written.

"The heliotrope operator was called a "heliotroper" or "flasher" and would sometimes employ a second mirror for communicating with the instrument station through heliography, a form of language using impulsed reflecting surfaces. (i.e. what we would call flashing-code!)"

The heliotrope, which since not being originally designed to send or receive code could be operated by one man, was a pair of mirrors and telescope set all in one. It was utilized by surveyors as a specialized form of target; it was employed during large triangulation surveys where, because of the great distance between stations (usually twenty miles or more), a regular target would appear indistinct. Soon however there were developments to use it for code sending and the sender could not look through and hold the telescope steady while keying or hand tilting a mirror, so the dedicated Heliograph was made. Both the Heliotrope and the Heliograph had a flat mirror with a non-silvered opening at the centre of the plate. During the use of the flat mirror, the angle of the cone of reflected sun offered a base diameter of about 50 feet at one mile and 1000 feet at 20 miles.

Therefore, high accuracy was not required when directing the mirror at the instrument station but constant adjustment was needed to take account for the movement of the sun.

Note: Later (around 1880) there were Heliograph sets with different sized mirrors with different dispersion angles for different distances and improved security (Less dispersion means less chance of detection and also of the enemy reading the code.) or you could add snoot tubes to ensure the signalling went only as directed. But I am Jumping way ahead.

"The Great Trigonometrical Survey of India." (1830 to 1851) was commenced with Heliotropes and flag signalling, and soon with Heliostats, then Heliographs. The task of Measuring and mapping India was under the direction of Colonel Sir G. Everest in 1832, after whom Queen Victoria on her Coronation in 1837 decided that in honour of his skill, a Large Mountain should be built and named. This was planned as a way to employ the hands of idle soldiers and stop them turning to self-abuse, something that the Queen (as most Victorians) was deeply concerned about! The last piece of this massive British construction was carried up in May 29,1953 by Sir Edmund Hillary, NZ and Tenzing Norgay, NP and cemented into place just in time for the Coronation of another Queen and Grand daughter of the aforesaid Queen Victoria, Due to a misprint the title of the newspaper report of the actual completion was accidentally changed from "Mount Everest Concreted!" to "Mount Everest Conquered!" :-)

Back to serous mode, it should be mentioned that the accuracy of the Survey was so good that the height of Mt. Everest was determined to be 29,018 feet, and in later survey in 1954 to be 29,028 feet (8,848 meters) or ten feet higher than the original survey determined. Much later with the aid of GPS measurements and Satellite radar measurements it was actually found that the peak was actually an inch under an exact 29,000', which would correspond to 8840 meters. Why the differences? The first measurement did not take into account three factors which also played a role in giving false readings for the 1954 survey. refractive effects in the atmosphere had on the optical equipment, the sloping snow surface on to which the theodolites were aligned which changed height according to time of year and snow thickness, and deviations of the keeping the head of the tripod horizontal or the plum-line where used vertical-- because of a tendency of mountains to give a slight gravitational tug on the spirit level. GPS of course is almost completely immune to these factors.

The travel writer Jan Morris (who accompanied the 1953 British expedition as the Times correspondent to the top and radioed the report of the completion back to the base station) was asked "What was so remarkable about getting to the top of a mountain?". She wrote in Time: 100 People of the Century, "by any rational standards, this was no big deal. Aircraft had long before flown over the summit, and within a few decades literally hundreds of other people from many nations would climb Everest too. [...] Geography was not furthered by the achievement, scientific progress was scarcely hastened, and nothing new was discovered. Yet the names of Hillary and Tenzing went instantly into all languages as the names of heroes, partly because they really were men of heroic mould but chiefly because they represented so compellingly the spirit of their time."

James Morris, as Jan was back then, was the correspondent for The Times of London, and was the team signaller, and instrumental in sending out the coded message that ensured news of success broke in England on the Coronation Day of Queen Elizabeth II. Morris (b.1926), In 1972, nearly two decades after winning international plaudits for his Everest reporting - years of mental anguish during which he nevertheless persisted with conformity (marriage and children) - she underwent male-to-female sex-reassignment surgery, and began living as Jan Morris.

Figure 3. Headlines for the Queen's Coronation day

Figure 3. Headlines for the Queen's Coronation day

Some facts, in case you meet the Mountain at a cheese and wine party in your area! As said it took the name Everest after Sir George Everest in 1865, the British surveyor-general of India. Before George married her, she was simply known as Peak 15, Last known Location: Latitude 27° 59' N.....Longitude 86° 56' E, but does move around a bit, currently at a rate of three quarter of an inch northwards per year.. It's summit ridge separates Nepal and Tibet so one of these countries is slowly and sneakily stealing the land of the other.

An anonymous Everest summiteer was asked "what was the hardest thing about climbing Mount Everest?" . "Pissing through 6 inches of clothes with a 3 inch penis", he replied (i.e. the different Fly's of Multiple layered clothing). Petra's Tip for Explorers: Never, ever, eat the yellow snow!!!

So without the heliograph the height would probably have been wrongly guessed and maybe declared to be a hundred feet higher than it really was. Had this happened Sir Edmund Hillary would have had to carry up a big step ladder and a 100 foot flag pole to get his flag to the top :-)

The Invention of the Heliograph provided more reliable (and just as important reproducible) results, and greater signalling distances than flagging or Heliotropes/Heliostats had ever had, and the greater the size of the triangles in the triangulation the better the accuracy of the mapping. The distances were referred to as "marching's", then the teams were sent marching to some pre-agreed distant location to set up. So in some reports of Heliography you might see the signalling range (size of mirrors, etc.) given as a "marching range!"

For every Team (a minimum of three teams were needed for Triangulation) there were Signallers, A signalling party of three men was usually found sufficient to manipulate a pair of heliotropes - one for single, two for double reflection, according to the sun's position-and a lamp, throughout the night and day. Heliotropers were also employed at the observing stations to flash instructions to the signallers.

Between 1790 and 1805, the resulting cartographic work was carried out back at the Tower of London in the Drawing Room of the Ordnance Survey by civilians working under Royal Engineer officers. In 1805 the civilians were formed into the Royal Corps of Military Surveyors and Draughtsmen. That Corps was disbanded in 1817. Seven years after Gauss made his invention!

In the mid 1800's Britain launched an export drive to convince the French of the benefits of the new Sandwich and Wellington boot, but feeling insulted by French jaunts that they tasted exactly the same, and also since the French were cheating conscientious British servicemen who ordering Heliographs to improve their signalling skills, but were instead sent "naughty French maid photographs" we had an axe to grind. So some surveying work was delayed while we discussed the menu with a waiter called Bonaparte!

Figure 4. Defeating (De-feet-ing) the French by hurling tight Wellington boots at them!

Figure 4.
Defeating (De-feet-ing) the French by hurling tight Wellington boots at them!

Wellington is shown in the above illustration taking on the French at the new sport of "Welly-tossing" or "left-boot-hurling" during an early Victorian BBC "Its-a-knock-out" contest in Waterloo. Playing the joker he got double points for this throw. When we won we were presented with a whooping great big Railway station and matching Bridge, which at great cost was dragged by the rails back to London to become a key part of a song by the Kinks.

After the Napoleonic wars, the Survey's work was extended to undertake a survey of Ireland.

To aid this operation a regular and disciplined labour force was provided by the formation in 1824 and 1825 of three Survey Companies, the 13th, 14th and 16th Companies of the Royal Sappers and Miners (Royal Signals Granddaddy and father of the R.E.). Another Company, the 19th, was formed in 1848, and all four were transferred to the Royal Engineers, from which their officers came, in 1856. The 16th Company was disbanded in 1906, and the remainder reconstituted as the Survey Battalion, RE, in 1929.

With the altered conditions after the end of the Second World War the Battalion itself was disbanded in 1946. These Survey Companies did not function as ordinary Royal Engineer Companies, the personnel being distributed throughout the Ordinance Survey. Until just after the Second World War, men serving with the Ordnance Survey might be either Royal Engineers or Civil Assistants. It should be remembered that only a proportion of the staff of the Ordnance Survey was in the Royal Engineers.

Surveyors today still use skills and tools learnt from these Empire measuring days, of which the Royal Signals (albeit then as Sappers) added their part.

Line vs. Heliograph

The heliograph was in its peak at the time that another new medium was being developed, wire-line telegraphy! The two chief drawbacks of line however from the military point of view, were that the line itself was readily cut and that messages could be intercepted by tapping.

On occasions, the line after being cut was used by the opposing forces to pass its own messages. Line cutting was an occupation much favoured by the Boers, as not only did it interrupt British communications, but it also provided splendid opportunities for ambushing British lines parties with inadequate escorts.

For instance, on 3 May 1901, the Manchester Regiment's line parties suffered casualties. The telegraph wire between Witklip and Badfontein, having been cut during the previous night, parties were sent out from each end but were attacked by about 50 Boers. The fire was so heavy that it was impossible to mend the wire, which was found to be cut in twelve places.

One native killed, L/C Davies, 1st Manchester Regt., slightly wounded another, and two men missing. Similarly, line tapping was a most popular Boer activity. To overcome it, the British fed false information down their line in clear and later encoded messages and corrections gave the intended communication.

Latin was considered secure, but with General Smuts having little else in his saddlebags but Kant's Critique of Pure Reason and a Greek New Testament, while General Hertzog had his Tacitus with him, clearly Latin was less secure than the British believed. Satis dicit.

The Boers however preferred the Heliograph for their communications and were as adept if not better than the British! That said the Heliograph was not good in inclement weather, or on a moonless night, so the Signaller had to learn and master more than one tool, and flags or lamps were a constant alternative.

The main disadvantages of the heliograph were as said that a light source was required, be it the sun, the moon, or a concentrated limelight lantern, and that a clear atmosphere was essential.

Tactically, interception was possible anywhere along the axis of the projected light beam (line of sight), but this was sometimes much reduced in diameter by the use of a narrow tube called a snoot. Even a artillery barrel could be used to project the beam.

The disadvantage in this was that the signalling distances of these very narrow beams were greatly reduced, as less light was radiated.

Heliographs in the British Army

Figure 5. The 5th Lancers Field Service Kit (A Hand-coloured Postcard)

Figure 5. The 5th Lancers Field Service Kit

NCO to Signaller at Heliograph. "Signaller, flash them that due to the total cloud cover we have had for the last hour, they should switch to flags! Ask them to heliograph back three flashes if they understand!"

The Mark V in the picture above dates it from about 1904 to well into the first world war. The postcard is posed, then lack of the Shadows (with or without Cliff Richard) even under the horse, shows that there was currently no sun to signal with! In the Picture above the Leather case can be seen hanging on the tripod of a Mk V Heliograph, and a set of flags leis slovenly on the ground as a back up should "clouds stop play!"

It is evident from the use of the second mirror that the sun was high and/or just behind the signaller, but as said the lack of shadows (especially under the horse) tends to suggest this was a posed photo even if the sloppy handling of the flags might lead to think otherwise. In some 1880's British Army photos, the mirrors appear to be 10" or 12" in diameter instead of basic 5" one shown above.

The heliograph that was used in the British Army for signalling to a distant point and were issued to at least regimental/battalion level and, of course, each column had its own equipment. It comprised of a sturdy wooden tripod of which each leg was adjustable. The mirror assembly was usually kept safely packed in a stout leather case and/or wooden box. The Mirrors were packed separately into protective tins.

Under the middle of the Tripod is a sturdy hook onto which a sandbag, rock or other heavy weight could be hung to prevent the tripod "walking" during signalling!

This hook is NOT as so often seen (incl. In the Royal Signals Museum) for hanging the leather carrying case on! The Case is actually to be hung "round the legs of the tripod" as shown in Figure 8 above or in figure one on the front page.

The chain for the screw cap (Thread protector) and the Loop for the carrying sling, act together to prevent the carrying strap of the leather-case slipping down and pulling the legs together.

Figure 6. 2nd Gurkha Rifles / Sirmoor Regiment Signalling Unit (from ~ 1896)

Figure 6. 2nd Gurkha Rifles / Sirmoor Regiment Signalling Unit (from ~ 1896)

As can be seen in this Picture of the Signallers of the 2nd Gurkha Rifles / Sirmoor Regiment Signalling Unit, from about 1896, there was a significant technology transfer via the deployment of Heliographic equipment and skills. Standing behind the Heliographer is the Signalling officer.(Note: he has Breast Pockets, where the others don't ) to the right is a flag-waver at rest and kneeling, and behind him a messenger recording the message being read.

Unlike figure 5., here there is sun, and it is in the right direction and angle for the Heliograph as it is shown. So although more posed than Fig. 5., it is more authentic in set-up and use.

The Gurkhas were quick and skilful students, learning not only the Morse and flag-waving codes, but also to spell, read and write, etc. which was by no means common for them at that time! The technology transfer served us well and the Gurkhas and Royal Signals have been close ever since.

The Zulu War

By far the most significant use of the Heliograph in conflict was the part it took in the Zulu wars and later wars against the Boars.

The Newspaper "Harpers Weekly" dated 31st of May, 1879 printed a report of the Heliograph at war under the title: The Zulu War - The Heliograph at Work, Flashing Messages to a Beleaguered Force.

This print was a typical Victorian engraving and made an impressive centre spread with a lot of detailed text around the engraving concerning the Heliograph. (Double page spread, size 22 x 15.5 inches)

Compare in the two pictures (Fig. 7 and Fig. 8) below, showing the above described newspaper print version with the coloured print that can be obtained from the Royal Signals Museum Shop.

They are subtly different, but "not a lot!", as Paul Daniels used to say.

Figure 7. The Heliograph at the Tugela River (Harpers Weekly Engraving)

Figure 7. The Heliograph at the Tugela River

Figure 8. The Heliograph at the Tugela River (A Coloured Reprint)

Figure 8. The Heliograph at the Tugela River (A Coloured Reprint)

from    comes the following text.

Up to their arrival in Zululand, C Troop had used the heliostat as one of their visual instruments. They were now issued with four heliographs which had been manufactured by the Bengal Sappers and Miners in their workshops at Roorkee. These were found to be excellent and to give a much steadier signal. The heliostat used a fixed mirror which reflected a steady beam to the distant station. The beam was interrupted by a shutter, making morse signals possible. The heliograph had an oscillating mirror which, when operated, reflected the elements of the morse signal to the distant station. Part of the force became beleaguered in Fort Ekowe, the ground between them and the Tugela River being entirely in Zulu hands.

At Tugela, Lieutenant Haynes RE, in spite of the pessimistic discouragement of his seniors, spent a week heliographing in the direction of Fort Ekowe before he received an answer.

At the other end, Major Wynne RE had noticed the signal almost immediately, but found that shaving mirrors would not serve. He spent the week constructing a large screen which pivoted from the horizontal to the vertical, the space of time of the vertical appearances producing the elements of the morse code. Traffic passed, but Major Wynne was exhausted and became fatally ill that same day.

As a result of the Telegraph Troop's persistence, communications with the beleaguered force were established and a relief operation mounted which saved the garrison.

You can buy a (20" x 16") colour print of 'Tugela River' from the Royal Signals Museum Shop

Here is a link to the on-line museum shop

However the Heliograph was not only used in Afghanistan, India and south Aria, but also used in locations closer to home such as in the Crimea, and even in Europe ( on sunny days!)

From the History of the 3rd (UK) Division Headquarters and Signal Regiment we read following.

The 3rd Division was raised in 1806 during the Peninsular War and at this time dispatch riders provided communications essential for successful command. The Army Telegraph Train provided line heliograph communication for the 3rd Division during the Crimean War and following this campaign the Telegraph Troop RE was formed in Blandford in 1870 which by 1884 had grown to a telegraph Battalion. No 3 Detachment of this Battalion deployed with 3rd Division to fight in the Boer War from 1892 to 1902. On return to the UK this was retitled 3rd Division Signals and located at Bulford. In 1937 Divisional Signals was mechanized and in 1939 mobilised as part of the British Expeditionary Force and took part in the Dunkirk withdrawal.

Simplified description of Heliography Basics

The following description is greatly simplified and in part goes against the real set up and use of the Military Heliograph. The original description (from 1905) on the use of the Mk V Army Heliograph can be found in the Annex to this datasheet. See Figure 9 bellow for the respective component parts described here.

Figure 9. The Heliograph Basic Function

Figure 9. The Heliograph Basic Functions

The basic functions of the Heliograph

If the sun (A) is in front of the station (i.e. towards the target) the Signalling Mirror (C) is used alone. If the sun is directly overhead or behind the addition of the Duplex Mirror (B) on an arm (coloured Dk Blue / Purple) turned to the appropriate side so as to be not quite in the way, but reflect strongest light, helps redirect the light to Signalling Mirror (C).

Aligning the Unsilvered black spot of the mirror (or hole through the back) with the cross hairs of the target for a Line-of-Sight (F to E) sets up the basic direction. Once this is found, then the vertical azimuth needs setting to light up the cross hairs of the sight arm with a depressed key. , it may be necessary to turn the mirror horizontally by turning the "U" frame (coloured light blue and yellow in my drawing) and then tightening the thumb screw (J).

Releasing the key lets the light go up into the sky and become unseen by the distant station! Pressing the key (G) for normal signalling code raises the lever (H) and causes the Mirror (C) to tilt forward and flash to the distant station. i.e. the light beam dips from angle (D) to the required signal angle (E). Releasing the key allows the beam to rise up to (D) again!

If the sun is in front, the Signalling Mirror (C) needs constant adjustment to account for the sun traversing the sky. If the sun is above or behind the station, the fitting and use of Duplex Mirror (B) is required and this needs adjusting with wing nuts (K and L) to keep the sun onto the centre of the signalling mirror!

Once these simple basics are understood, we can describe the main differences in Army use.

In the Vance heliograph, the mirror does not dip on key depression, but rises. This was a problem when signalling over an enemy held valley or river as anyone in the LoS under the signal path could read a negative (dark signalling) version of the code.

Also to align the centre of the mirror onto the target the mirror is looked into from approximately the angle of the sun, (i.e. so your head puts the mirror into shadow) and looking at the shadow spot, move till the spot is indicating the distant location. the sighting rod is moved until it's cross hairs are now between the spot and the distant station, then a flip-up vane raised and the signalling mirror moved till sunbeam with clamped down (depressed key) hits the centre of this vane.

The army also decided that the signalling mirror (the one that moves during keying) must always face the sun, and so if the sun was behind you the Heliograph was to be set up to face away from distant station. The outgoing signal was to be redirected back towards the target by the second (duplex) mirror. This rule simplified learning the method for adjustment, then the trim for sun passage was always done with the same adjustment screws, etc. on the main signalling mirror.

To widen the beam and make the Heliograph suitable for use on a moving deck of a ship or to signal to a moving ship offshore, etc. there was a diffuser glass in a frame like the mirror that could be added in place of the sighting arm, or on its own arm.

The Mk V made it even simpler to align by simply removing the sighting vane and using a marked sight on the centre of the redirecting "Duplex" mirror, now the user had only to ensure the spot of the signalling mirror and centre of the reflector, were identically aligned to the distant station reflection!

Figure 10. A Mk V used on left with Sighting rod and on right with the Duplex mirror

10. A Mk V used on left with Sighting rod and on right with the Duplex mirror

A complete Heliograph set as shown in the left picture was recently sold brand new and unused in e-Bay for a bargain sum of US $37.50 so it is worth keeping your eyes and ears open.

Figure 10. A Mk V used on left with Sighting rod and on right with the Duplex mirror

10. A Mk V used on left with Sighting rod and on right with the Duplex mirror

The 1911 Encyclopaedia Says.

At first a code book was used and the signals represented code words, but it was found better to revert to the telegraphic system of signalling by the Morse alphabet, amongst the undeniable advantages of which was the fact that it was used both by the postal service and the telegraph units of Royal Engineers. Thenceforward, in ever-increasing perfection, the work of signallers has been a feature of almost every campaign of the British army. To the original flags have been added the heliograph (for long-distance work), the semaphore system of the Royal Navy (for very rapid signalling at short distances), and the lamps of various kinds for working by night. Full and detailed instructions for the proper performance of the work, which provide for almost every possible contingency, have been published and are enforced.

The apparatus employed for signalling in the British service consists of flags, large and small, heliograph and lamp for night work. The distances at which their signals can be read vary very considerably, the flags having but a limited scope of usefulness, whilst the range of a heliograph is very great indeed. Whether it be 10 or 100 miles away, it has been found in practice that, given good sunlight, nothing but the presence of an intervening physical obstacle, such as a ridge or wood, prevents communication. For shorter distances moonlight, and even artificial light, have on occasion been employed as the source of light. In northern Europe the use of the instrument is much restricted by climate, and, further, stretches of plain country, permitting of a line of vision between distant hills, are not often found. It is in the wilder parts of the earth, that is to say in colonial theatres of war, that the astonishing value of the heliograph is displayed. In European warfare flag signalling is more usually employed. The flags in use are blue and white, the former for work with light, the latter for dark backgrounds. The same principle is followed in the heliograph.

This instrument, invented by Sir Henry C. Mance, receives on a mirror, and thence casts upon the distant station, the rays of the sun; the working of a small key controls the flashes by throwing the mirror slightly off its alignment and thus obscuring the light from the party reading signals. The fact that the heliograph requires sunlight, as mentioned above, militates against its employment in Great Britain, but where it is possible to use it, it is by far the best means of signalling. Secrecy and rapidity are its chief advantages.

An observer 6 miles. distant would see none of its light if he were more than 50 yds. on one side of the exact alignment, whereas a flag signal could be read from almost every hill within range. None of the physical exertion required for fast signalling with the flag is required to manipulate the instrument at a high rate of speed. The whole apparatus is packed in a light and portable form. An alternative method of using the heliograph is to keep the rays permanently on the distant point, a shutter of some kind being used in front of it to produce obscurations.

Fig. 12. from a German description of their version of Mk.5

12. from a German description of their version of Mk.5

When in use the heliograph is fixed upon. a tripod. A tangent screw (E) which moves the whole instrument (except the jointed arm L) turns the mirror in any direction. Metal U-shaped arms (C) carry the mirror (B), which is controlled by the vertical rod (J) and its clamping screw (K). The signalling mirror itself (usually having a surface of 5 in. diameter) is of glass, an unsilvered spot (R) being left In the centre. This spot retains its position through all movements in any plane. The instrument is aligned by means of the sighting vane (P) fixed in the jointed arm L, and the rays of the sun are then brought on to the distant station by turning the horizontal and vertical adjustments until the "shadow spot" cast by the unsilvered centre of the mirror appears on the vane. The heliograph is thus ready, and signals are made by the depression and release of the "collar" (I) which, with the pivoted arm (U, V), acts as a telegraph key. When the sun makes an angle of more than 120 degrees with the mirror and the distant station, a "duplex mirror" is used in place of the sighting vane. The process of alignment is in. this case a little more complicated. Various other means of making dots and dashes are referred to in the official work, ranging from the "collapsible drum" hung on a mast to the rough but effective improvisation of a heliograph out of a shaving-glass. The employment of the beams of the search-light to make flashes on clouds is also a method of signalling which has been. in practice very effective.

Signalling is used on most campaigns to a large extent. In the Tirah expedition, 1897 and 1898, one signal station received and sent, between the 1st and 18th November, as many as 980 messages by heliograph, some of which were 200 to 300 words in length. It is often used as an auxiliary to the field telegraph, especially in mountainous countries, and when the wire is liable to be cut and stolen by hostile natives. In the Waziri expedition, 1881, communication was maintained direct for a distance of 70 miles with a 5-in, heliograph. In the Boer War, 1899-1902, the system of heliographic signalling was employed very extensively by both sides.

Modern Heliographers

In the USA there is a strong following of Heliograph enthusiast. A demonstration was held by James Riddle, KD7AOI at Fort Huachuca in the USA on Nov 15, 2001, for members of the Current US forces to demonstrate the setting up and use of the Heliograph. In the photo above James correctly hangs the case around the tripod legs and not on the hook under the middle, then the hook is only for suspension of a stabilising weight / sandbag.

In this photo the signalling soldier is "catching" the shadow spot. It is cast on his hand by an unsilvered spot in the centre of the heliograph mirror as he aligns the instrument to place the spot in the exact centre of the sighting vane. The same procedure would apply if he were using a duplex mirror in place of the sight.

Figure 13. Modern Heliographers (Demo) at Fort Huachuca in the USA

13. Modern Heliographers (Demo) at Fort Huachuca
in the USA

Photo by kind permission of James Riddel: See his Heliography Web-site

The Heliograph, the Heliotrope

Source: The Telegraph: A History of Morse's Invention and its Predecessors in the United States by Lewis Coe TK 5115 C54 1993 McFarland and Company, Publishers ISBN 0-89950-736-0 (page 8)

"One of the most successful and widely used visual signalling systems, the heliograph, did not appear until 1865, long after most visual systems were considered obsolete. The factor that established the heliograph was the existence of the Morse alphabet of dots and dashes, widely used for land telegraph and submarine cable operations.

The ancients understood the principles of reflected sunlight, but no one ever got around to devising a code for the letters of the alphabet. Signal codes of some type had existed long before Morse, but none of them ever reached a level of universal acceptance, and they were mostly forgotten by the time Morse published his code.

"Early in the nineteenth century, Gauss, a German mathematician, had discovered the tremendous potential of the sun's rays reflected from a plane mirror. Through experiments he was able to demonstrate that even a small mirror one inch square could send flashes that could be seen over a distance of seven miles."

The silvered glass mirror, invented in 1840 by Justin Liebeg, paved the way for the heliograph. (...)

"Like the American army, the British did not have a separate Signal Corps organization until the 1860s. The first British signal school was established at Chatham in 1865.

Shortly after, a young officer named Henry Christopher Mance (1840-1926) became interested in signalling with the sun. Mance, later to be knighted for his achievements in engineering, knew of the use of mirror instruments called heliotropes in the triangulation of India.

The Indian survey, one of the great engineering projects of the nineteenth century, required accurate location of high mountain peaks to serve as control points for the ground survey.

Bright fire pots were used at night and the heliotropes by day. It is not know whether any Morse code signalling was done by heliotrope, but it is certain that prearranged signals were exchanged.

(...) "The simple and effective instrument that Mance invented was to be an important part of military communications for the next 40 years. Limited to use in sunlight, the heliograph became the most efficient visual signalling device ever known.

In pre-radio days it was often the only means of communication that could span ranges of up to 100 miles with a lightweight portable instrument.

"The Mance instrument employed tripod-mounted mirrors, with one mirror linked to a key mechanism. The key tilted the mirror enough to turn the flash on and off at the distant station in accordance with the dots and dashes of the Morse code.

Range was line-of-sight, with atmospheric conditions establishing the upper limit. The British army found the Mance heliograph ideally suited to field operations in India and Afghanistan.

It was used to transmit daily reports and orders to and from the remote mountain posts and for tactical communications when troops were in the field. (One hundred ten years later, TV pictures were to show Afghan guerrilla units using British pattern heliographs in their conflict with the Russians.)

The present Afghans have found the heliograph useful for the same reason as their British enemies of old; namely, a simple uncomplicated mechanism that requires no batteries or complex maintenance."

A Code of Morals by Mr. Rudyard Kipling

Lest you should think this story true I merely mention I Evolved it lately.
'Tis a most Unmitigated misstatement.

Now Jones had left his new-wed bride - to keep his house in order,
and take away to the Hurrum Hills above the Afghan border,
to sit on a rock with a heliograph; but 'ere he left, he taught his wife
the workings of the flashing Code that sets the miles at naught.

And Love had made him very sage, as Nature made her fair;
So Cupid and Apollo linked, per 'Heliograph', the pair.
At dawn, across the Hurrum Hills, he flashed her counsel wise-
At evening, the dying sunset bore her husband's homilies.

He warned her 'gainst seductive youths in scarlet clad and gold,
As much as 'gainst the blandishments paternal of the old;
But kept his gravest warnings for (hereby the ditty hangs)
That snowy-haired Lothario, Lieutenant-General Bangs.

'Twas General Bangs, with Aide and Staff, who tittupped on the way,
When they beheld a Heliograph's flash tempestuously at play.
They thought of Border risings, and of stations sacked and burnt-
So stopped to take the message down-and this is what they learnt-

"Dash dot dot dot, dot dash, dot dash dot" twice. The General swore.
"Was ever General Officer addressed as 'dear' before?
"'My Love,' I'. faith! 'My Duck,' Gadzooks! 'My darling popsy-wop!'
"Spirit of great Lord Wolseley, who is on that mountaintop?"

The artless Aide-de-camp was mute; the gilded Staff were still,
As, dumb with pent-up mirth, they booked that message from the hill;
For clear as summer lightning-flare, the husband's warning ran:-
"Don't dance or ride with General Bangs-a most immoral man."

[At dawn, across the Hurrum Hills, he flashed her counsel wise-
But, howsoever Love be blind, the world at large hath eyes.]
With damnatory dot and dash he heliographed his wife
Some interesting details of the General's private life.

The artless Aide-de-camp was mute, the shining Staff were still,
And red and ever redder grew the General's shaven gill.
And this is what he said at last (his feelings matter not):-
"I think we've tapped a private line. Hi! Threes about there! Trot!"

All honour unto Bangs, for ne'er did Jones thereafter know
By word or act official who read off that helio' signal.
But the tale is on the Frontier, and from Michni to Mooltan
They know the worthy General as "that most immoral man."

E-Bay and Signals History

The heliograph set shown in figure 10 shows that there are a lot of interesting things to be found on e-bay, and despite being over a hundred years old, due to a lack of knowledge or interest by people not knowing how to use it, and what maybe they have, you can grab a slice of history for a relatively small sum. The post card shown in Fig. 6 is also from e-bay.

You can also learn a lot then many sellers give descriptions to their wares from the handbook or other sources and so give a free history lesson! But beware of red herrings like the sellers of "WW1 Royal Signals Cap Badges" (using the 1926 to 1947 version) I keep seeing!

The Black and White print (from the centre spread of the Harpers weekly Newspaper) and show in this data sheet as Fig. 7, has also just sold in e-bay for $US 11.01, so the bargains are out there somewhere "Scully", you need only keep your eyes open.

Question. Have you ever used a Heliograph? Or even ever seen one in the RQMS? If so let us know. we would like to add your experiences / info to this datasheet.