World Exhibition Paris 1878

New Technologies

May 1, 1878 - October 31, 1878


Back - List of Pavilions

Central building

Central building at the Exhibition Expo Paris 1878

Architect(s) : Gabriel-Jean-Antoine Davioud, Jules Bourdais

When the visitor, leaving the park of the Champ de Mars, steps onto the Pont d'Iéna and the magnificent rotunda of the Palais du Trocadéro, flanked by its two circular galleries, suddenly appears to him, he stops in admiration; it is impossible to dream of a more dazzling spectacle than that of this monumental palace, at the foot of which the waterfall unfolds its silvery waves.

"It is from the Jena bridge, says M. André Treille in the Rappel, that one can best judge the effect produced. At this distance, one can perceive very well the noise made by the masses of water, falling and colliding. In the same way, at a distance of ten leagues, one can hear the muffled rumours produced by the fall of Niagara. Just as one can see the Niagara Falls from very close, so one can have the pleasure of contemplating the Trocadero Falls and almost touching it, thanks to the terrace that has been built below. If you are not afraid of getting your feet wet and catching coryza, it is a sight to behold; you go to the sub-terrace, a liquid cloud falls before your eyes. If the sun is shining, every drop appears to be on fire, set on fire by the fires reflected in it. It looks like a marvellous magic lantern, which has not been forgotten to light up, but where the historiated glasses have not been passed through. Wait a little; the sun is falling on the horizon. Suddenly, through the layer of water, indistinct shapes fade vaguely.

"This time you seem to see the profile of a Dutch town through the evening mists, as Van Hier's brush has shown us so many. Wait a little longer; the image becomes clearer, the shapes take shape, although their outlines retain a vaguely bluish tint, as if you were looking through a prism. Are we in the Sahara and do we think we see, at the end of the endless desert, palm trees that are not there, caravans that do not pass by, cities that do not exist there: a mirage effect? But no! We are under the vault of the waterfall, which has nothing of the Sahara, and what we see, through the disturbed mirror of the bubbling waters, are the multicoloured banners floating above the monuments: It is the workmen who go up and down the ramps of the hill, busy, not wasting a second; it is the pavilions of all kinds that are being built; the imposing facade of the galleries of the Champ de Mars, on the crest of which the last rays of the sun are playing; and over there, as a background to the picture, the great city that unfolds, as far as the human eye can see, the capricious arabesques of its irregular roofs, and that erects on all sides the chimneys of its factories, the bold lines of its monuments.

"I swear to you that this spectacle is worth seeing.

The order of the monument, its architecture are of an unquestionable originality and the conception of it belongs entirely to its authors; we cannot praise their work too much; it has the majestic scale which was appropriate to its destination.

The slope of the land has made it possible to group together on the sides of the parks, monuments, even of a certain importance, without them detracting from the perspective of the main monument.

The Trocadero Palace, which, as our readers already know, will survive the Exhibition and, despite its distance from the centre of Paris, will be used for festivals, conferences, etc., etc., is built entirely of masonry with an iron framework. The greatest difficulties had to be overcome before the desired solidity could be assured, for the ground of the Trocadero was criss-crossed with underground galleries, the last vestiges of quarries now exhausted.

M. Gabriel Lafaille gave the following beautiful description of this marvellous palace:
"Contemporary architecture has found its Parthenon. It is now an established fact: the 19th century has an architecture. For a long time, it was thought that we would miss this glory. Better than the Opera, whose location is defective, whose economy is too heterogeneous and whose monumental line is entirely sacrificed to ornamentation; better than the Opera, I say, the Trocadero Palace will mark the eighth characteristic transformation of our national architecture. For it is not only in its whole that this construction is original, it is also original in its details, some of which already show a very firm style. The capital, that architectural criterion, where the trials and tribulations of the transitional periods are so keenly felt, seems to have achieved its definitive character in the new monument. I noticed two kinds: one with mascarons, not too prominent, forming a sheath at the end of a square column; the other with curved foliage, less majestic in effect than the famous vase of Corinth, but just as elegant.

"In addition, there is nothing that recalls the fossil tradition or the old wanderings of the Academy; hardly any clichéd details, which fade into the enormity of the mass. The colonnades have a Florentine look that the backbench of the Institute will secretly disavow. The domes do not conform to the formula, and the triangular attic was not considered obligatory.

"The general plan is a marvel. Its realization exceeds the idea that could have been conceived from the drawings. It forms a half-moon, or rather the segment of a circle which, once completed, would encompass the Trocadero, the quays, the river and part of the Champ de Mars. But in an edifice one must admire not so much the proportions as the order, and in this respect the Trocadero Palace seems to me to be superior to all the constructions of similar plan which belong to previous eras, I mean the Collège des Quatre-Nations, the châteaux of the eighteenth century which are so beautiful in the north of France, certain German monuments of the end of the last century, and the Palace of Parliament in Washington.

"The central pavilion, with its two wings, is a sort of colossal bird with a flight bent into an arc, like that of hawks or falcons and the most graceful ploughmen in the ether. Certainly, it is not of the Trocadero palace that Frederick II would have made this criticism so deserved by that of Versailles: "A pigeon's body with eagle's wings".

"The first floor consists of a semicircular loggia, high, narrow and airy, with numerous bays whose arches, formed by sections of flared volutes, describe a row of elegant and robust ogives. The outer wall is clad with square pilasters which, by their strong projection, replace the classical colonnade with more solidity and no less grace. These pilasters are disproportionate, and their stylobates rest on the frontispiece of the water feature that serves as the base of the central part of the monument.

"The second floor, in contrast, forms a low and wide promenoir, paved with a mosaic very sober in colour and design, with square columns, whose shafts, engaged in the slab in the manner of certain pillars of the Romanesque period, combat in a happy way the crushing of the ceiling.

"A terrace offering an unparalleled view of Paris forms the third floor. From there the dome rises, flanked by its two towers and surmounted by the Renommée of M. Mercié. Around the terrace is a balustrade interrupted by pedestals supporting statues.

"The wings of the palace are harmoniously attached to the central body and develop their colonnaded galleries with magnificent breadth. Each of the head pavilions has a lead finial of a very elegant design at the base of its lightning rod.

"The whole ensemble is airy, luminous, grandiose, simple, without severity, as befits a temple of art.

"Because of its position, the water feature is an integral part of the building. It seems to have been inspired by the one in Saint-Cloud (a more beautiful model could not have been chosen). It is decorated with statues by our first sculptors: Falguière, Millet, Hiolle, Schœnewerk. The masonry of the basins is made of this cream-coloured marble which is called Auteuil stone, and which it seems to me is wrong to use for exterior works, because its crumbly grain crumbles in the air and the rain soon makes it lose its lustre.

"The garden, or rather the immense parterre which levels its beds on the slope of the height, presents true floral wonders.

"The Festival Hall, the only room in the rotunda, to which two large staircases give access, is superb. The immense window openings would have pierced the facades of the building, but the architects had the good sense to decorate them with ribbed mullions in the style of late 16th century churches, which serve as frames for the stained glass windows made in Paris and Evreux.

"In short, the Exposition of 1878 will have the advantage over that of 1867 of leaving something after it, the Trocadero Palace, which will perpetuate its memory.

"Ah! if Paris still had all that it has destroyed in the last three hundred years, what a dream of stone and marble it would be! for there is no city in the world, not excepting Rome and Athens, which has had as many monumental splendours as Paris. Athens had only one physiognomy. Rome has had two: the pagan and the Catholic. In ten centuries, Paris has had five.

The platform of the towers is 104 metres above the ground in the Place du Roi de Rome, i.e. 14 metres higher than the towers of Notre-Dame.

In order to spare the legs of the visitors, these towers have been provided with lifts; without this convenience, it is probable that many people, stopped by fear of fatigue, would have deprived themselves of the magnificent spectacle which unfolds before their eyes from the top of these two towers, and which is more extensive than that which is witnessed from the gallery alone.

Everything is beautiful in the palace, and everything harmonises marvellously; they have been able to give the work conceived the right degree of severity, they have also been able to avoid vulgarity; the two semicircular galleries that run to the right and left of the central pavilion are of undeniable majesty; the vestibule of the main entrance, by the Place du Roi de Rome, is also very grand in terms of its ornamentation and its size; it is 60 metres wide.

It is through this vestibule that one arrives at the magnificent Festival Hall, whose dome is eight metres higher than that of St Peter's in Rome.

When this hall was built, two major difficulties were encountered: acoustics and ventilation.

Mr. Charles Blanc told in the newspaper Le Temps how this double problem was solved; we have borrowed his interesting account:


L'ACOUSTIQUE

"The problem to be solved was this: to raise a hall larger than all known halls and to build it in conditions of acoustics well enough calculated not to be rendered useless by the inordinate size of a vessel fifty metres in diameter. To get an idea of these proportions, it is sufficient to know that the diameter of an ordinary theatre, that of the Théâtre-Lyrique, for example, is no more than fifteen metres. In plan, the figure of the hall is in the form of a horseshoe arch. The orchestra is placed in a curve which blends with the horseshoe arch, closing it, and is covered by a vault of cul-de-four material.
"The famous Albert Hall in London is designed in the form of an ellipse, and the orchestra is grouped at one of the focal points, so that, by virtue of the law of sound repercussion, the people lined up around the second focal point of the ellipse hear perfectly, while at all the other points of the hall, only confused vibrations are perceived, choppy waves, a sort of hubbub.
"The architects of the Trocadero, Messrs Davioud and Bourdais, wanted to avoid this pitfall at all costs, and here is how they studied their project from the point of view of acoustics. Our readers will certainly be curious to know this, as we were curious to learn it. It goes without saying that one cannot test the acoustics of a hall that costs two or three million to build, unless one resolves to rebuild it every time the test fails. It was therefore necessary, in the absence of a positive experiment, to make a mental one, so to speak, by taking a strict account of the planned arrangements. And first of all, those who wanted to carry out these delicate tests started and had to start from this principle: that sound behaves absolutely like light, in the sense that the sound waves are reflected by the surrounding walls, in the same way that the light rays are reflected by these same walls. To say it in passing, nature, although infinitely varied in its creations, is simple in its laws, and, far from multiplying them, it has reduced their number as much as possible.
"This being the case, a model in miniature was constructed at little cost, reproducing exactly the arrangements of the great hall, and in which the vault which covers the orchestra, instead of being made of reverberating materials, was constructed of reverberating materials, that is to say, covered with tinned copper. By placing a light in the mathematical centre of the orchestra, where the soloist should be standing, it was found that the tiers where the audience would be seated received the light reflected by the vault alone. It goes without saying that the small model hall was kept dark and that only the benches of the audience were lit. Convinced by this experience, the architects of the palace padded all the walls of the hall so that the sound was dampened. On the contrary, the walls of the vault, under which the orchestra is placed, were made repercussive by the choice of materials, so as to reflect the sound onto the spectators, or, to put it better, onto the listeners, in conditions analogous to those of a mirror reflecting light rays.
"However, such an arrangement had a serious disadvantage: the danger of echoes. Each listener must simultaneously hear the direct sound and the reflected sound, which is called resonance. If the interval between the perception of the direct sound and that of its resonance is greater than a tenth of a second, your two sounds, instead of merging in the ear, are perceived distinctly, and what was a resonance becomes an echo. Now, given that sound travels a distance of 340 metres in one second, it was necessary to collect and send back only those sounds separated from each other by an interval of 34 metres at most.
"But the research of the very skilful and conscientious architects of the Trocadero was not limited to this. Having recognised, by the experiments made with the light in the small model of their hall, that the seats furthest from the orchestra were not more illuminated than the seats closest to it, they rightly found that this was an unfortunate equality, for it is natural that the listeners furthest away should receive, in compensation for their distance, a greater amount of reflected sound. On the basis of this observation, they modified the curve of the vault that was to reflect the sound, so that it reflected the sound waves more abundantly on the last benches of the amphitheatre than on the first. In short, if the problem is solved, as we have every reason to believe, it will have been solved by these two procedures: deafening of the hall in the parts close to the audience, by means of silk padded hangings, and abundant repercussion by the walls surrounding the orchestra and by the acoustic conch which dominates it...
Architecture," adds the eminent academician, "is not only an art: it is a science. It cannot be properly judged without knowing whether the builder, doubled as an artist, has reconciled the useful with the beautiful and has united them so closely that the one is only the highlighting of the other, that is to say that the beautiful is the projection of the useful."


VENTILATION.

Now here is how the problem of ventilation was solved, which proves that, according to the desire of M. Charles Blanc, the beautiful and the useful were perfectly reconciled:

"Since the Trocadero hall can hold 6,000 people, it was necessary for each of them to consume four cubic metres of breathable air per hour. To satisfy this hygienic requirement, the air was introduced into the hall, not through the windows, which were completely closed and let in only light, but through a circular opening in the roof of the amphitheatre, measuring fifteen metres in diameter, an enormous opening, much larger than the famous eye of the Pantheon in Rome, which is only nine metres in diameter. The air, which descends into the hall through this opening, which is covered on the outside by a lantern, will be drawn from the quarries dug under the palace and which communicate with the garden by a vast ventilation shaft. By means of this ingenious process, the public filling the amphitheatre will enjoy air that is cooled in summer and warmed in winter. We know that the temperature is constant in the underground; it is even more constant the deeper the underground. It follows that the temperature of the air drawn from these catacombs and poured from above into the room will also be more or less constant. I say approximately, because we must take into account the difference that the cold or hot air entering the ventilation shaft may make. For the cold season, we have therefore provided heaters through which the air will pass and which will raise it to the desirable and healthy temperature. But as the air, to enter the room, needs to be injected, propelled, it will be done by means of two propellers, driven by a twenty horsepower steam engine.
"This is not all: the air breathed in by the spectators will flow through an opening in the back of each seat, the section of which is calculated so that the release of the air breathed in is equal to the renewal of the air to be breathed. This suction, outside, of the interior air breathed, and consequently vitiated, will be done by means of two propellers functioning in opposite directions, and which will carry this vitiated air to the top of the lantern, at the height of the bronze Victory of Antonin Mercié... ".
We knew that the system of ventilation had for some time made notable progress; but it had not yet been applied, we believe, on such a large scale, nor especially with such success.

On each side of the festival hall is a large rectangular room; these rooms are intended for meetings, conferences, congresses, etc., which the Minister will have authorised.

The galleries on the wings of the main building contain the retrospective exhibition and the historical portraits.

©Les Merveilles de l'Exposition de 1878