_Automatic Regulation_ (Figs 5 and 6).--The upper part of the rod, _e'_, carries a cam, _f_, that plays freely between two connecting rods, _f¹_, and the travel of which is limited by two rollers, _f²_ and _f³_, situated between the rods, _f_, which latter are themselves suspended from a rod, F. The latter slides in a support, F², which serves likewise as a guide to the rods, _q'_ and _t²_, of the slide-valves, and which is fixed upon a projection cast in a piece with the frame, B, and is suspended from the short arm of a bent lever, F', whose longer arm carries a roller that runs in a vertical groove, _t³_, in the back of the expansion slide-valve. The lower extremity of the connecting rods, _f'_, is connected with the sleeve of the regulator, Q, by a lever, _f^{4}_, and a bent lever, Q'. This latter revolves on an axis passing through its elbow and mounted at the extremity of a projection that is cast in a piece with the support of the regulator. This bent lever is prolonged beyond the sleeve, and carries suspended from its extremity a small piston-rod that plays in a dash pot, Q³, and limits the too abrupt motions of the apparatus. The regulator is driven by a belt and through the intermedium of the bevel pinions, _u_. It is easy now to understand the purpose and the _modus operandi_ of the mechanism that permits the regulator to act upon the expansion gear. When running normally the connecting-rods, _f'_, occupy a vertical position, and the rollers, _f²_ and _f³_, are placed exactly at the two extremities of the travel of the cam, _f_. When the velocity exceeds the normal, the sleeve of the regulator rises and the lever, Q', tips to the right and forces the rods, _f'_, to oscillate in the same direction around their upper joint. After that, the lower roller, _f²_, being situated on the line of travel of the convex part of the cam, will be carried along by the latter and cause an oscillation to the right of 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.