holds the guides. The height of the legs is 10.25 meters, and their weight, with the guides, 250 tons. The binding plates weigh together about 25 tons, and the foundation plates 90 tons.

The entablature of the frame work weighs 30 tons; on it is placed the steam cylinder, single acting, made in two pieces, each 3 meters long united by flanges and bolts. The diameter of the cylinder is 1.9 meters, giving a surface of 27,345 square centimeters (deducting the section of the rod, which is 36 centimeters in diameter); which, for 5 atmospheres, gives a pressure under the piston of about 140 tons. As the weight of the hammer is 100 tons, it is evident that it can be raised with great velocity.

The stroke of the piston in the cylinder is 5 meters. This height of fall, multiplied by the 100,000 kilogrammes of the mass, gives a working force of 500,000 kilogrammeters, or about 1,640 foot tons. The width between the legs is 7.5 meters, and the free height under the cross ties 3 meters, thus providing ample space for maneuvering large masses of metal.

The entire height of this colossal structure from the base of the masonry foundation to the upper part of the steam cylinder is 31 meters (102 feet), but notwithstanding this unfavorable condition for stability and the enormous effect resulting from a shock of 500,000 kilogrammeters, everything is so well proportioned that there is but slight vibration.

The workman who maneuvers the hammer is placed on a platform on one of the legs, about 3 meters above the floor. He is here protected from the heat reflected from the mass of metal during the operation of forging.

PLAN FOR AN ELEVATED RAILWAY AT PARIS.

Elevated railways have been in operation for a long time in New York, Berlin, and Vienna, and the city of Paris has decided to have recourse to this mode of carriage, so indispensable to large cities. The question of establishing a line of railways in our capital has been open, as well known, since 1871. During this period of nearly fourteen years this grave subject has at various times given rise to serious discussions, in which the most competent engineers have taken part, and numerous projects relating to the solution that it calls for have been put forth.

The problem to be solved is of the most complex nature, and the engineers who have studied it have not been able to come to an agreement except as regards a small number of points. It may even be said that unanimity exists upon but a single point, and that is that the means of locomotion in Paris do not answer the requirements of the public, and that there is an urgent necessity for new ones. The capital question, that of knowing whether the railway to be built shall be beneath or above ground, is not yet settled; for, up to the present, no project has been prescribed in one direction or the other.

While some extol the underground solution as being the only one that, without interfering with circulation in the streets, permits of establishing a double-track railway capable of giving passage to ordinary rolling stock and of connecting directly with the large lines, others, objecting that such a road could not give satisfaction to the taste of Parisians, and that it would necessitate work out of proportion to the advantages gained, conclude upon the adoption of an open air railway.

Preferences generally are evidently for this latter solution.

We have received from a learned engineer, Mr. Jules Garnier, a project for an elevated railway, which appears to us to be very ably conceived, very well studied out, and which we hasten to make known.

(1.) The system is characterized by the following fundamental points: The up and down tracks, instead of being laid alongside of each other, as in an ordinary railway, are superposed upon two distinct platforms forming a viaduct, which is consequently so arranged as to permit of the laying of one of the tracks at its lower part and of the other at its upper.

(2.) The system of