the bent lever, F. The piece, t', will then be pushed back in such a way as to partially close the inlet orifices of the slide-valve, t, and, as the steam will thereupon enter into less quantity, the engine will quickly resume its normal velocity. If the velocity becomes less that the normal the action will be just the opposite of that just described.

The Large Cylinder (Figs. 1 and 2).—The two eccentrics, E and E', which control the distributing gear of the small cylinder, A, actuate at the same time that of the large one, C, through two rods, e² and e³; such distribution is also effected by means of a sliding-plate valve. The two steam ports are 45 millimeters and the exhaust port 84 millimeters in diameter.

The large cylinder is 650 millimeters in diameter, and 930 in length. The stroke of the piston is 650 millimeters.

The Feed-Water Heater (Figs. 1 and 2).—The exhaust from the small cylinder enters the heater through a pipe, r, 140 millimeters in diameter. This feed-water heater consists of a large cast iron cylinder, 400 millimeters in internal diameter, and 1.15 meters in length, connected with the pipe, r, on the one hand, and with the cylinder, C, on the other, by means of two couplings, R' and R². In its interior are arranged 60 copper tubes, of 29 millimeters internal, and 31½ millimeters external diameter. These tubes are fixed at their extremities into two circular supports that are riveted to the interior of the cylinder. The exhaust from the small cylinder passes into these tubes, around which circulates steam coming directly from the boiler through the tube, r', and escapes toward the bottom, with the condensed water, through the tube, r². The heater is surrounded with a 2 mm. plate iron jacket.

A communication, r³, with a valve-cock, R³, permits of the introduction, into the large cylinder, of the steam from the heater. The exhaust steam from the large cylinder goes directly to the condenser, but there is likewise provided a pipe through which it may make its exit into the open air, in case, for example, the condenser needs repairing or there is a failure of water.

The Condenser (Figs. 1, 2, and 4).—The condenser is represented, half in section and half in external view and in elevation in Fig. 1, and in plan in Fig. 2; Fig. 4 is a transverse view of it. It consists of a large cast iron chest, D, bolted by means of its flanged base to a masonry support. This chest is cast in a piece with a pump chamber, D', in which works a piston mounted on the prolongation, d', of the piston-rod of the cylinder, C. The diameter of this piston is 210 millimeters, and its stroke is 650. The condensing jet, whose flow is regulated by the cock, d², is brought into contact with the steam by a rose, d³, which divides it into small drops.

The pump is a double acting one. Its valves are of rubber, and the passage-way allowed the water is, in each of them, in section, one-half that of the piston. The rod, d', slides in a stuffing-box, with metallic lining, which is shown in Fig. 10.

Lubrication.—The lubrication of the crank-pin presents some peculiarities. Two stationary cups, z, are placed at the upper part of the guides, as seen in Fig. 3. These distribute their oil, drop by drop, into two reservoirs, z', fixed to the upper axis of the vertical connecting-rod. Two small brass tubes, resting against the connecting-rod, lead the lubricator into cavities in the head of the horizontal connecting-rod, M'. One of these cavities corresponds to the crank-pin and the other to the lower axis of the vertical connecting-rod. The lubrication of the cylinders is effected automatically by means of a Consolin apparatus (Fig. 1), based upon the condensation of the steam and upon the difference between the density of the oil and condensed water.

Diagram of Distribution (Fig. 11).—We shall first examine that which relates to the small cylinder. The eccentric of the distributing slide-valves is adjusted to 123° with respect to the crank, and that of the expansion slide-valves to 170°, that is to say, so that the angles of advance are respectively 55 and 57 millimeters for these two cylinders.

Let us trace two axes, o x and o y, at right angles, and a semi-circumference of any radius whatever, o m, which shall represent the travel of the crank-pin. Let us draw the line, o A, making with o y an angle of advance of 33°, and the length of which is equal to the eccentricity of the distributing slide-valve, say 55 millimeters, and let us describe a circumference on this length taken as a diameter. Let us trace in the same way the line, o B, making with o y an angle of advance of 80°, and let us describe upon this line a circumference equal in diameter to the eccentricity of the distributing slide-valve, say 57 millimeters.

Finally, let us trace points, o and c, as centers of arcs of circles having respectively for radii the distance between the centers of the circumferences just mentioned and the eccentricity of the expansion slide-valve. These two arcs will intersect each other at a point, c², which is thus the fourth angle of a parallelogram whose other angles are the points, c, c', and o. From the point, c², as a center let us describe a circle passing through o.

In short, we obtain three circles that are such that the vector radii, starting from the point, o, and limited at the said circles, represent, for the first, the deviations to the right of the distributing slide-valve beginning at the middle of its travel, the second the deviations of the expansion slide-valve, and the third the relative deviations of the distributing with respect to the expansion slide-valve.

Let us complete the diagram by describing, from the point, o, as a center, circumferences having for respective radii the length, o e, of the external overlap of the distributing slide-valve, and the lengths, o i and o i', corresponding to the minimum and maximum of the interval between one of the edges of the expansion slide-valve and the external edge of the corresponding inlet orifice of the distributing slide-valve, when the axes of these two valves coincide.

These radii have the values: o e = 25 mm.; o i = 8 mm.; and o i' = 42 mm. Let us now prolong the radii, o d, o d', o d², and o f, until they meet the crank circle, and let us then project these points of intersection upon a line, M M', parallel with o x, and we shall have all the elements that are necessary to study the different phases of the distribution in the small cylinder.

Let us complete this diagram in such a way as to study also the distribution in the large cylinder:

In this cylinder the distribution cannot be modified, that is to say, the active length of the expansion slide-valve is invariable. The interval comprised between one of the edges of this valve and the internal edge of the corresponding inlet orifice is equal, then, to 28 mm. when the axes of the two valves coincide.

Let us describe, from o as a center, a circle having this length for a radius, and let us again project the intersections of the radius, o k, with the crank circle upon a parallel at M M'. The external overlap, being the same as in the small cylinder, say 25 millimeters, the circle, o e, already traced for the distribution in the small cylinder, will serve for the distribution in the large one. Let us join its intersection with the circle, c, and the center, o, and let us trace also the circle of the internal overlap and the radii, o g, and o h, and we shall have all the elements of the distribution.

Advantages of the Engine.—The engine that we have just described