On the Esplanade des Invalides, on the edge of both the Decauville railway and the main avenue that runs along the Esplanade, the Pavilion des Postes et Télégraphes is a modest building which, despite its lacklustre appearance, is nonetheless very interesting.
Its main entrance opens onto a vestibule that forms a forecourt on the short side, facing the Seine. A similar vestibule adorns the other short side. The two large façades have no doors and are opened only by large three-bay windows. At the four corners of the pediment stand chimeras which symbolise I don't know what; telegraphy, nor the post office, having nothing chimerical about it. These fabulous animals can perhaps be explained by the generally mythological tendency that governed the ornamentation of the pavilion, whose façade - the one that faces the avenue - is decorated with a Minerva and a Mercury.
The entrance hall is preceded by a small garden, the fence of which already constitutes the beginning of an exhibition. The fence is made of metal telegraph poles... The introduction of metal in the installation of telegraph lines seems to offer the same difficulties as that of metal sleepers in the construction of railways. It is often discussed and has been for a long time, and the injected wooden post is still used, which, if it offers lesser conditions of duration, has the advantage of being infinitely less costly to establish.
The garden, the entrance and the vestibule exhibits are devoted to lines, modes of suspension, overhead, underground and underwater conductors. On each side of the door there are columns formed by crowns of conducting wires. These conductors are made of iron, bronze, silicon bronze and pure copper. We are not yet sure which is the best. Nevertheless, siliceous bronze seems to be in the lead; it is very popular today.
Naturally, a machine for making underwater conductors was to be found here. These conductors are of various kinds, differing from each other by the nature of the insulators. The first attempts at submarine telegraphy were interrupted because of insufficient insulation, and the cables were armoured with archal wire, lead pipes and steel spirals. Today, they are made very simply. The sheath, made of a fine copper twist, is first surrounded by a double hemp reed, then covered with a reed, also double, of metal wire; finally it is impregnated with antiseptic substances and covered with a spiral of insulating cloth. This assembly constitutes a conductor: the combination of four or five conductors in an insulating envelope, the main part of which is made of gutta-percha, forms a cable. On landings, this cable is protected in a more serious manner: if necessary, it is covered with a lead pipe.
Moreover, once submerged, the cable soon becomes unalterable; the underwater vegetation, the calcareous secretions of the zoophytes, surround it, entwine it and after a few years transform it into a long bead of rock laid on the bottom of the ocean, the duration of which is limited only by the duration of the conductors themselves.
The central room, or rather the only room - the vestibules being separate - is occupied by the telegraphic apparatus, some of which is simply exposed, while the others operate before the eyes of the public.
Let us pay tribute here to the kindness and complacency of the employees whom the administration has assigned to operate the apparatus. And, let us say it very quickly, these employees are not an exception, they represent with great dignity and also very exactly what the French employee is, that is to say a whole tradition of affability, courtesy and good manners. It is a rather general attitude to complain about government employees; but it is only an attitude which is quickly discarded by those who have had experience of what foreign administrations are like from the same point of view. Our postal and telegraph employee, that is to say, the one of all who is most frequently in contact with the public, does credit to both his administration and his country. And he is so often in pain that it is only fair that some of them should be honoured in the pavilion on the Esplanade des Invalides.
Telegraphic apparatus can be divided into two main categories: printing apparatus and signal apparatus. Apart from these, there are, it is true, electro-chemical devices, known as autographic, and Breguet's dial telegraph; but autographic devices have not been able to enter into practice and the dial device, which was once very popular because of its ease of use, is now only used by railway companies and private telegraphy. As it leaves no trace of the transmission, telephony will soon replace it everywhere or almost everywhere.
The type of signal apparatus is the Morse, whose conventional alphabet consists of bars and dots; it is simple, easy to operate, and costs barely 60 to 70 francs per station. It is the device for small offices. However, its transmission is rather slow. To remedy this, attempts have been made to develop duplex, quadruplex and multiplex devices, i.e. devices which take advantage of the intervals in the transmission of each sign, to transmit on the same line the signs coming from two, four or more manipulators, to the same number of receivers. These devices, applied to the Morse telegraph, have now been more or less abandoned.
More fortunate has been the Estienne device, which is a fast Morse. In the Morse, the dots are formed by pressing the finger on the manipulator button, and to obtain a bar, this pressure must be prolonged. In the Estienne, the manipulator carries two keys, one for the dot, the other for the bar, and this almost doubles the speed of the transmission. In the Morse, the succession of contacts produces a particular rhythm which the operators are able to grasp very quickly and which enables them to read a dispatch by ear, i.e. without looking at the tape on which the signs are printed. This is an advantage in ordinary telegraphy, but it is a serious disadvantage in military telegraphy, since it is sufficient to place at any point on the line a device similar to the initial contacts, in order to catch the meaning of the dispatches. This disadvantage, which does not exist in the Estienne, has led the Germans to adopt this French device for military telegraphy.
But the real practical device, the one which, in twenty years, has entered into all international relations, is the Hughes printer, a device of American origin, but which has received many improvements from French telegraphers.
It should be noted in passing that our telegraphers are in love with their profession and their apparatus, and that many of them spend their lives seeking improvements. There is no year in which the annals of telegraphy are not enriched by some useful discovery due to an obscure employee, not all of whom have achieved the just fame of the Baudots and Meuniers.
I have said that the Hughes had more than twenty years of practice, and this leads me to note a curious peculiarity of electrical science.
The two inventions which have contributed most to the diffusion of electricity in the field of common practice are undoubtedly the printing telegraph of the American Hughes, and the dynamo-electric machine of the Frenchman Gramme, for the production of light. These two types are of about the same period, and since then, as if from the first day their authors had laid down the perfect principle in all its extent, telegraphs and dynamos have been mere repetitions, improvements, or simply complications of the Hughes and Gramme models.
Twenty years later, the Hughes is still the best telegraph, just as the Gramme is the best dynamo.
These repetitions and improvements of the Hughes are quite numerous at the Telegraph Pavilion. It is well known what the typical device consists of: A wheel carrying printing characters can be operated by a mechanical motor, when the current establishes a relationship between this motor and the wheel. Under these conditions, pressure causes the character currently in contact with the paper to be printed on a strip of paper. Initially, it is a keyboard that determines the formation of the current which, in conditions of rigorous synchronism between the mechanical manipulator motor and the mechanical receiver motor, will rigorously activate the two motors in the same way and consequently the two wheels that depend on them. Thus, at the same time, under the action of a finger pressing a key on the keyboard, a letter is printed on the arrival and departure, the employee thus checking his work himself.
A highly skilled employee can transmit up to 3,000 words in an hour.
This speed could, it seems, be increased, and this is the purpose of the Parment telegraph, which is merely an ingeniously improved Hughes. One of its improvements consists in increasing the number of letters engraved on the printing wheel. In the Hughes, this wheel carries only one of each of the necessary types, letters, numbers and punctuation marks, and these types are placed in their alphabetical order. If, for example, we have to telegraph the word end, one turn of the wheel will suffice, since the letters f, i, and n are placed in alphabetical order; but if we wish to transmit the word foot, four turns of the wheel will be necessary, since the four letters are placed in reverse alphabetical order.
Mr. Parment, on the other hand, has placed the letters on the wheel according to their typographical value, i.e. in the order of the most frequent coupling and by repeating several times in different places, those which occur more often. This device must, it seems, be able to triple the speed of transmission.
Automatic telegraphs are represented in several types. In telegraphy, automaticity consists either in eliminating the work of the sending employee or in eliminating the work of the intermediate employees when retransmission takes place. It is easy to understand what retransmission is. A dispatch is sent from Paris to La Verpillière via Grenoble. Paris is connected directly to Lyon, Lyon directly to Grenoble, and Grenoble directly to La Verpillière; in order to bring the telegram to its destination, it will be necessary to retransmit it to Lyon and Grenoble, that is to say, to receive it and send it back, which requires two intermediate employees. Automatic telegraphy eliminates these employees and their work. This is one of the means used. It is based on the principle of the Parment telegraph already mentioned, but it is based on the general data of automatic telegraphy.
Initially, the dispatch is transcribed by means of a perforator which gives, instead of a handwritten dispatch, a sheet of paper perforated with dots and bars, roughly similar to Morse code prints. This sheet of paper is suitably connected to the manipulator, which transmits the telegram to the intermediate station, where a printout (Hughes system) and a perforation are produced simultaneously. This perforation is then connected to the manipulator of the intermediate station to obtain a new transmission, which in turn can give rise to a further intermediate perforation.
Other automatic systems are the Wheatstone, which produces a perforated strip without printing, and the Bernard Meyer, which produces both a perforation and a Morse print.
M. Bernard Meyer is, I believe, the inventor of autographic telegraphy which is based on the decomposition of certain metallic or metallic salt coatings by electric current... M. d'Arlincourt also exhibited an autographic apparatus. But these two systems are, as I have said, still rather far from practical realization.
The multiple transmission devices... applied to the Hughes have been more successful than those applied to the Morse. I have mentioned the names of Messrs. Baudot and Meunier. The latter is the inventor of a multiplex apparatus which can transmit in both directions and by a single wire, a number of simultaneous telegrams which is fantastic.
The public takes great interest in this very well laid out and explained exhibition, which is lacking in many other installations. In a few minutes, we have a very attractive lesson in things that can be continued by visiting the Post Office exhibition.
This one is simpler. It basically shows an overview of letter sorting in a post office. The sorting process is represented by the glass-bottomed rack in which the sorted letters are stacked; the glass bottom prevents a letter from being forgotten.
A mail wagon, converted into a mobile office. Everyone has seen these mysterious wagons, almost as enclosed as prison cell cars, on the railways. But very few people have been able to penetrate their mysteries. At the Esplanade, one can break through this arcane and visit the mail wagon. It is a large office, simply but comfortably set up. Pigeonholes occupy the four sides up to the height of the support. These racks receive the sorting of the bagged letters, already partly sorted by the sending offices. While the train is moving, the postman, seated in front of a shelf, distributes the contents of the bags into the boxes. During the day he is lit by portholes, at night by strong lamps, and in winter he has a stove to heat him. It is a hard job to be an itinerant or a conveyor.
At each station the office takes and leaves the mail from or to that station. It has long been tried to eliminate the need for stops at small stations, at which the station trains, high-speed trains, could thus not stop. At Pont-sur-Seine (Aube), a system of removing and returning the despatch bag without stopping the train has been in operation since 1885. Gela has not yet become widespread, in France at least; for in America dispatches are taken and left in this way, and I believe even travellers to some extent; but that is in America.
A reduction of the Pont-sur-Seine machine is exhibited in the Pavilion of the Post Office, next to a curious mosaic painting, which includes no less than 30,000 postage stamps, stuck one next to the other.
The Post Office Exhibition is completed, in the telegraph room, by the collection of printing plates used for the printing of postage stamps and by a reproduction of the microscopic dispatches on film, transmitted by carrier pigeons during the siege of Paris.
Finally, behind the Pavilion, there is a series of the carriages of the Post Office Administration, those carriages well known to Parisians, whose correct drivers do not shout, do not swear, never hang up, and whose horses do not know what it is to spread themselves. It is wonderful to see them going through the most crowded streets always well and always without accident.
A regret to finish: Why didn't you bring some pedestrians, some modest rural postmen, to stand guard at the Pavilion des Postes et Télégraphes.
Whatever the songs, more or less funny, and the more or less witty handwritten news, the rural postman is not so laughable.
There are those who, in rain, snow, storm, sun and avalanches, go out every day to the Jura, the Pyrenees or the Alps to cut down their ten leagues of mountains and more, and this for a derisory salary. Believe me, in doing this arduous job one ends up intoxicated by the pride of his hard work. The soldier doesn't get drunk in any other way.
That's why it would have been good to show some of these brave men with their coats, their big shoes and their shod sticks, who are going to carry the letter with the clumsily written address of the little boy to the old mother or the young fiancée in a remote corner, to the isolated hut.
It would have made one think a little of the amount of daily courage and obscure devotion that the simple letter with its modest three-penny stamp generates on its way, alongside prodigies of science, intelligence and industry.
©Livre d'Or de l'Exposition - Paul Le Jeinisel.