_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: