At the foot of the Eiffel Tower, between the Finnish pavilion and that of the Gas Company, the Telephone Company has set up a pavilion, which contains at the same time its exhibition and the office of the telephone service of the Universal Exhibition.
As a construction, this pavilion represents the type of building par excellence; it is made of iron-reinforced wood, or, if one likes it better, of wood-reinforced iron. For example, the main uprights are made of quadruple fir planks, connected by bolts, while the beams are made of I-iron, lined with two fir planks, one on each side. The exterior is made of wooden panels, mounted on T-irons. All the transverse parts, having rigorously the same dimension (3m,30), are interchangeable, so to speak, and the whole assembly, screwed, iron on wood or wood on iron, can be adjusted with the help of screwdrivers or English spanners, if the variations of the atmosphere make the wood swell or warp, or dilate the metal. It's hardly a house anymore, it's a Black Forest cuckoo clock.
But one must do this kind of construction justice, that it is perfectly in keeping with the nature of the telephone itself. What indeed is a telephone system? A set of devices, conductors, stations, etc., which must be attached by application and by superimposition to already existing buildings, with the least possible damage to them, and with the least possible expenditure of time and money. What better, therefore, to synthesise the telephone system than this pavilion, which could have been erected in a few hours, if it had not been necessary, in order to find suitable ground, to carry out foundation work which makes the underpinning much more important than the external construction.
The Société des téléphones had a pavilion built, consisting of a central part and two wings.
The central part is surmounted by a telephone turret, known as the concentration turret. This turret is on the model of those which surmount the central stations of the telephones, in the cities where one did not think it necessary to impose on the telephone companies the ruinous underground installations.
I said ruinous; these installations are ruinous above all for the consumers, because the companies, who do not intend to lose out, - and they are quite right to do so - are forced to raise the price of subscriptions in a truly exorbitant manner. Thus we pay 600 francs a year in Paris for a subscription to the urban network alone, while in Belgium we pay 60 francs, ten times less, to enjoy the use of the Belgian network, which includes several towns, and therefore a very considerable extent.
It is perhaps in order to convince the government to authorise these aerial installations that the Société des téléphones has shown its turret flanked by harrows, which fulfil the same purpose of bringing together wires leading, for example, to the same house.
Let us enter the pavilion and examine it in detail. First of all, the first idea for the telephone was put forward by a Frenchman, M. Bourseul, who published his ideas in 1854. Unfortunately, he did not go any further.
It was not until 1876 that Bell installed the first telephone and it was in November 1877 that the telephone was first introduced in Europe, where it aroused the greatest curiosity and admiration. For his part, Edison sought to improve the device and thought of using battery power.
For some time the improvements made were nil, but they became important when the invention of the microphone gave a new impulse to the question.
How far are we from the string telephones, real children's toys, which should nevertheless have long since tempted the spirit of improvement of our physicists, but they did not deign to concern themselves with it, it was too old, it went back to 1667.
The general principle of telephones is as follows. The vibrations of the voice are communicated to a vibrating plate placed in front of a magnet. The end of the magnet is wrapped with a long copper wire surrounded by silk. This is the transmitter.
The receiver is identically similar, if not in form, but in construction, and it is the same wire which, forming a coil in the transmitter, will also wind around the magnet of the receiver, also in a coil, so that this copper wire is endless. And the transmitter can be very far away, as long as it is connected to the receiver by the same wire.
If you speak in front of the vibrating plate, the back and forth movement of the plate reacts to the magnetic force of the magnet and generates an electric current in the wire which is transmitted to the receiver. Under the influence of this current, the magnet of the latter will undergo the same variations in magnetic force as the first, and the plate, more or less attracted, will start to vibrate to reproduce the voice. What is transmitted is therefore not, strictly speaking, the voice, but a series of electric wave currents which reproduce it.
To increase the range of telephones, microphones have been added. Their shape is very variable, they are small sticks or balls of charcoal, which also vibrate, increasing the intensity of the sound.
In 1879, three companies were licensed to install telephone service. They operated three different systems; Grower, Edison and Blake.
The following year the three companies merged and formed the : Société générale des téléphones.
The first authorisations given were renewed until September 1889. And today the Company becomes, for the operation of the lines, the property of the State, not without protests from the Company, which is the owner of its apparatus, workshops and sales shops. For the Company had taken on the large-scale manufacture of cables. For this purpose, it had acquired the Rattier factory in Bezons, which was a rubber factory.
In the centre of the Telephone Pavilion, on the first floor, is an office, all set up and functioning to ensure the service of the Exhibition.
Each subscriber has a special line, leading to a central office, where the employees give the requested communications. But as it is not possible to put one ring per subscriber, there is a special system represented in the top of the central switch. When you want to call, a small plate falls down, showing the subscriber's number and, when it falls down, closes the circuit of the ringing bell.
Below the series of numbers are the switches, arranged in Jack-Knifs. This name comes from the fact that the contact spring was originally like a knife blade, and that this arrangement was due to a Canadian named Jack. It is through these switches that the subscribers of the office relate to each other.
The third and lowest part still has Jack-Knifs, but for subscribers of different offices.
Numerous plugs are suspended all along the desk to act on the Jack-Knifs, they are composed of two metal parts, isolated from each other, and fitted to the same handle.
So if a subscriber wants a call, he warns, a plate falls down showing his number, at the same time as the bell rings.
The ladies, in charge of the office service, get in touch with the subscriber to ask him whom he wants to speak to, the employee warns the person indicated that he is wanted and when he is answered, she puts the two subscribers in touch by means of a card.
This is very simple in appearance, but requires a great deal of practice.
The telephone wires are underground. They run through the sewers to the great central office, 27, Avenue de l'Opéra, of which there are several thousand. They are covered with gutta-percha, and joined together in bundles of about ten, in lead tubes. These wires arrive in the cellar and are spread out in a circle around four large holes made on the four sides of a chamber located in the middle of the cellar. This arrangement is shown in the lower part of the pavilion on the Champs de Mars. Then the wires go back up to the office, to be distributed to the various switches. As far as possible, the subscribers who are most often in contact with each other are brought together.
The station installed at the Exhibition gives immediate communication with any subscriber at the central office. As for the auxiliary lines in towns where there are several offices, they are considered as an ordinary line.
Finally, an advantage that the employees appreciate very much, they are seated.
The Berlhon-Ader device, consisting of an Ader receiver and a Berthon microphone, used exclusively by the Company, placed on a metal handle, makes it possible to have both the receiver at the ear and the transmitter in front of the mouth. This arrangement makes it the ultimate office device, allowing you to speak, hear and write as required.
Another convenient form is the Ader set with a magneto for calling and an electric bell. Here, the ringing works, thanks to a current determined by the rotation of a coil in front of a magnet. The transmitter is a small desk with a thin wooden plate in the middle, acting as a vibrating plate, the microphone is under this plate. This device is very common on foreign networks.
Finally, the same simple Ader set, without the magneto bell, of the form we represent, or of the column form, is much appreciated, for its accuracy, its regularity and its convenience.
The portable military set is the reduced form of the Ader set with magneto-electric ringing, but the transmitter and receiver are of the combined Berthon-Ader form. It weighs 7 kilograms.
Next to these devices, there are still fixed or mobile central stations in the exhibition, with several directions, as well as the new agar batteries. These are dry batteries, in which ammonia hydrochloride is suspended in kelp gelatine or agar-agar. These batteries are widely used.
There are also the most fanciful forms of ringing buttons.
In the window are telegraphs and relays, designed to increase the intensity of the current at certain times.
Adjacent to the central office is all the material built by the Company.
Firstly, rubber and all its various uses, either in soft or hard rubber: belts, hoses, valves, fabrics. There is also a very interesting exhibition of cables.
Telephone cables are mainly insulated with vulcanised rubber. Whether overhead or underground, they are strung in pairs to avoid induction effects.
There are also electric light cables and transatlantic cables.
The Company has telephone networks in Paris, Calais, Saint-Etienne, Le Havre, Rouen, Lyon, Marseille, Nantes, Algiers and Oran.
The line from Paris to Brussels has 314 kilometres. There is a double conductor wire made of siliceous bronze of 3 millimetres in diameter. This double conductor is fixed on the same poles as the telegraph wires, which created a rather great difficulty, because telegraph currents interfere greatly with telephone currents. To avoid this inconvenience, the telephone wires are crossed from distance to distance, so that the outgoing wire and the return wire are alternately closest to the telegraph wire, and this is sufficient to cancel out the induced currents.
The line from Paris to Marseilles is 800 kilometres long, and passes through Troyes, Dijon, Bourg, Lyon, Valence, Avignon, Arles, etc. It is also a double-wire overhead line, made of 4 1/2 millimetre silica bronze. The wires are crossed as on the Brussels line. There is an interruption at Lyon. The connection is made from Paris to Lyon, and Lyon gives the communication to Marseille.
Copper or iron wires have been abandoned as they were not strong enough. Phosphorous or siliceous bronze is now used exclusively. Also, with similar wires of 1 1/4 millimetres in diameter, it has been possible to space the poles 270 metres apart with 40 wires, in Antwerp there is a span of 275 metres with 125 wires, in Ghent a span of 340 metres with 3 wires. Finally, the line from the castle of Laeken to the Théâtre de la Monnaie has a span of 700 metres.
The most violent snowstorms do not damage these wires, and moreover, bronze does not oxidise like iron.
Let us not forget to mention the theatrical telephone auditions, which at the beginning so amazed the public. They take place in the lower part of the pavilion. And what is most intriguing is that not only do you hear the orchestra and the actors perfectly, but you even get the feeling of the actor's movement on the stage. This is how this is achieved:
Ader telephones are used for these auditions. For this purpose, a number of telephones are placed at the front of the stage parallel to the ramp, and on either side of the prompter's hole. Suppose there are ten telephones along the ramp, on either side of the prompter. For example, let's take the last phone on the left, near the sets, and the first phone on the right, near the prompter, and assume that these two phones are connected in such a way that the right phone reaches the right ear. If the actor is in the middle of the stage, the right-hand phone, which is closer, will be more influenced than the left-hand phone and the sounds will be more intense in the right ear than in the left ear. If the actor moves away, the sound naturally weakens, if he approaches from the left, the left ear will hear better. This simple procedure is most remarkable.
There are also concert auditions, in the four corners of the large office on the first floor of the pavilion. When you put in a 50 cent coin, a telephone is set in motion and you hear a piece of the concert.
The pavilion is really organised like a real theatre, with invisible actors underneath, but you can hear them perfectly. Sitting quietly in an armchair, one could attend our various theatrical performances, treat oneself to a revue every evening.
©Livre d'Or de l'Exposition - S. Favière.