The new installation, called the Central Station of the Quai de la Gare, is laid out on a very large scale, the total generating energy provided for being no less than 24,000 horse power; of this it is intended that 8,000 horse power will be in operation this year, and an extension of 10,000 horsepower in 1892; the power now in course of completion comprises four engines of 2,000 horse power each.  Four batteries of boilers will provide steam for these engines.  Figs. 2, 3, and 4 show the first section of the installation now in progress; the four groups of engines (three-cylinder condensing) are shown at 1, 2, 3, and 4; the four groups of boilers ranged behind them at F, F; the feed water heaters belonging to each group at V V.

[Illustration:  COMPRESSED AIR STATION ON THE QUA DE LA GARE, PARIS.  (FIG. 2,3,4)]

The end of the building abuts against the Seine, and the position of the water conduits for inlet and discharge are indicated at C and A respectively.  The installation, when completed, will include very extensive arrangements for transporting and storing coal, and the interior of the boiler houses will be furnished with an overhead system of rails and carriers for handling the coal automatically, as far as possible.  All the principal mains and steam pipes are made in duplicate, not only for greater security, but in order that each set of engines and boilers may be connected interchangeably without delay.  The Seine supplies an ample quantity of water, but not in a condition either for feeding the boilers, for condensation, or for the air compressors.

[Illustration:  THE NEW COMPRESSED AIR STATION AT PARIS. (FIG. 5, 6)]

Special provisions have therefore to be made to filter the water efficiently before it is used.  For this purpose the water is led to a group of four filters (see L, Fig. 4); from them it passes into the tanks, JJ, and is pumped into the heaters.  The filters can be rapidly and automatically cleaned by reversing the flow of water through them.  Figs. 5 and 6 show the general form of the type of engine adopted, as well as the engine house, some of the mains, etc.  They are vertical triple-expansion engines, and are being constructed by MM.  Schneider et Cie, of Creusot, with a guarantee of coal consumption not to exceed 1.54 lb. per horse power per hour, with a penalty of 2,000 francs for every 100 grammes in excess of this limit.  It is evident that with this restricted fuel consumption, a large margin for economy will exist at the new works, as compared with the St. Fargeau station, where the best engines cannot show anything like this result, while some of the earlier ones are distinctly extravagant, and the whole installation is handicapped with imperfect means of condensation.

Moreover, according to Professor Riedler, the consumption of steam by the new Schneider engines will be only 5.3 kilos. per horse power and per hour as compared with some of the large engines requiring 9 kilos., and the Cockerill engines—­using 8 kilos. per hour, not to speak of the older motors that are very extravagant in the use of steam.  The St. Fargeau station is worked under a further disadvantage.  The constantly increasing demand from subscribers taxes the resources of the station to their fullest extent, so that practically there is no reserve power.