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HomeContents > People > Photographers > René Patrice Proudhon Dagron

Other: R.P.P. Dagron 
Other: René Dagron 
Other: René P.P. Dagron 
Dates:  1818, 17 March - 1900, 13 June
Born:  France, Sarthe, Aillières-Beauvoir
Active:  France
French chemist, inventor of a plano-convex lens that would lead to the craze for a novelty optical toy, the Stanhope or Peep which he patented in 1860, and inventor of micropublishing. He was also the father of microfilming for spies and during the Franco-Prussian War (1870-1871) he was responsible for the microphotographs carried by pigeons during the siege of Paris.

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René Patrice Proudhon Dagron

Inventor of micropublishing and father of microfilming for spies.
By profession a chemist who, like so many of his trade, became a portrait photographer, was operating in Paris in the 1860s. As a supplement to his main income, which was derived from portrait work, Dagron specialised in the manufacture of microscopic views. These miniature photographs were mounted on a Stanhope lens and then inserted in such items as rings, tiepins, lorgnettes and pen-holders. The inspiration for these novelties probably dated back to Sir David Brewster's tours of France and Italy. Whilst in Paris in 1857 he exhibited a number of J.B. Dancer's microphotographs to members of the Académies des Sciences. They attracted considerable attention and, as Dagron was one of those present it is reasonable to assume that he foresaw immediately the potential of these tiny photographs. By 1864 Dagron had achieved a reputation as a skilful microphotographer and that year he published his Traité de Photographie Microscopique (Dagron et Cie, Paris). This skill was soon to be put to a more practical and spectacular application than the manufacture of souvenir novelties.
On 19th July 1870 war was declared between France and Prussia. Within two months the army of the Prussian Crown Prince arrived before Paris and the siege of the French capital began. On 12th September, ten days after the surrender of the Emperor Napoleon III and the French army of Chalons, a delegation of the newly formed Government of National Defence was established at Tours, some 200 km from Paris. The authorities at Tours considered various ways of maintaining communications between themselves and the now beleaguered French capital. The first pigeon despatch, dated 27th September, arrived in Paris on 1st October. About this time a chemist at Tours by the name of Barreswil proposed using reduced photographic prints of despatches in order to increase the amount of information carried by each pigeon. During that same month a professional photographer called Blaise successfully produced microphotos of despatches on photographic paper. Blaises microphotographs varied in size but generally had one side not much larger than 40 mm. He later doubled the content of each miniature by printing the reduced despatches on both sides of the paper. Blaise and a photographer named Terpereau were responsible for producing seventeen such double-sided microphotographs.
However, although a usable microphotographic despatch service was in operation from early October it became apparent that improvements were necessary if the system were to be maintained. One of the major problems seems to have been the shortage of pigeons, and especially of properly trained birds. It was, therefore, essential for each pigeon to carry as much information as possible. With this in mind the French government awarded Dagron a contract for the setting-up, outside Paris, of a microscopic despatch service. The contract was concluded on November 11th and the following day Dagron and his associates left for Clermont-Ferrand aboard two balloons (appropriately named 'Niépce' and 'Daguerre'). A change in the wind drifted the balloons eastwards towards the German lines and the 'Daguerre' was brought down by the Prussian guns. The 'Niépce', carrying Dagron, landed at Vipry-le-François which was in enemy held territory and it looked as if the whole enterprise might be doomed to failure. However, Dagron was nothing if not enterprising. It is said that he and his associates dressed as peasants and bluffed their way through the German lines.
Dagron finally reached Tours on the 21st November having been prevented, by the provincial authorities, from setting up an independent unit at Clermont-Ferrand, as had originally been intended. Dagron had lost most of his equipment with the two balloons and it was not until 4th December that he managed to produce a satisfactory microphotograph. Even this was far short of the quality he had originally hoped to achieve but, on 11th December he finally attained success. On 15th December the Delegation moved to Bordeaux and it was here that Dagron began work in earnest. The techniques he used proved extremely efficient and an account published in 1936 showed that "…they gave an enlargement of a finer degree of legibility than was possible on modern films and in the best apparatus at comparable reduction ratios." This comparison is perhaps a little unfair in that Dagron used a collodion emulsion which we should expect to exhibit a considerably finer grain size than the type of silver-gelatin microfilm emulsions commercially available in 1936. Dagron's achievement, however, was a formidable one and the method which he used showed considerable economy of means.
Messages to be sent were first subjected to abbreviation and the abbreviated copy then printed on transparent sheets divided into twelve rectangles measuring 80 mm x 110 mm. Each rectangle was able to contain 1,000 characters. The transparent sheets were then divided in two and the two halves contact printed with collodion plates to provide glass negatives of six rectangles each. After development the plates were cut into six pieces so that each rectangle formed one master negative. The master negative was photographed by a special camera having 20 lenses, each of short focal length. Thus 20 positive duplicates were made of the master simultaneously. Each print measured 30 mm x 55 mm and they were carried in small tubes attached to the pigeon's tail. It was possible for a single pigeon to carry 18 or more of these films, which weighed less than half a grain and contained more than 80,000 words.
The process was later modified to making a direct copy of each sheet. A dry plate of 36 mm x 60 mm was used and the resulting negative was contact printed onto a collodion plate. The collodion layer was then stripped from the plate after development. Each of these films or pellicles contained between 60,000 and 80,000 words and weighed only a twentieth of a gramme. Legibility was excellent despite the high ratio of reduction (40:1) employed. In nearly eight weeks Dagron and his assistants produced two and a half million copies of 115,000 separate messages. So efficient was the 'microscopic pigeon post' that when the siege ended only a few messages awaited despatch.
Dagron's contribution to microphotography was considerable. At the beginning of the Franco-Prussian War in 1870 only a small number of dedicated scientists and photographers were aware of the possible applications of microphotography. Eight weeks later the whole world knew of this marvellous method of disseminating information and it is clear that the Siege of Paris marked an important milestone in the history of micropublishing. It is also interesting to note that probably more document microfilms were made during the eight weeks siege than in the whole of the previous 30 years of microfilm's existence. Sad to say the end of the Franco-Prussian was accompanied by a decline in the general interest in microphotography. With the possible exception of the Rothschild Bank, who in 1875 employed Dagron to micro-copy their archives, no individual or organisation came forward to consolidate the gains made by Dagron in the public's mind.
A portrait of Rene P.P. Dagron is held by the Bibliothèque National in Paris.
A copy of his Traité de Photographie Microscopique (1864) is held by the Science Museum Library, London.
Examples of his Franco-Prussian War pellicles are held by the Kodak Museum, formerly of Harrow.
A description of Dagron's microphotographic process was published in the British Journal of Photography issue for December 20, 1971.
DAGRON, R.P.P., "Microscopic photography", British Journal of Photography, 1864, p.402.
DAGRON, R.P.P., Traité de Photographie Microscopique, Paris, 1864.
DAWSON, G. (Ed.), "Microphotography or Reduced Photographs", A Manual of Photography, 8th Edition, Chapter XV, 1873, pp.206-09.
GUNN, Michael J., Manual of Document Microphotography, Focal Press/Butterworth Scientific, London and Boston, 1985.
HAYHURST, J.D., The Pigeon Post into Paris, 1870-71, Ashford, 1970. HENDERSON, H.S. "The history of microphotographic slides", Microscopy, No.33, Jan-Jun 1977, p.139.
STEVENS, G.W.W., "Microscopic examination of some pigeon post pellicles", NMA Proceedings, 1959.
STEVENS, Guy W.W., Microphotography: Photography and Photofabrication at Extreme Resolution, 2nd. edit., Chapman and Hall, London, 1968.
© Michael J. Gunn (2006) - Used with permission  

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Pigeon post during the seige of Paris during the Franco-Prussian War (1870-1871) ... 
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