of the De Glehn Compound, and Fig. 18 shows the same type of gear as applied to furnish the motion of the valves of the low-pressure cylinders. In the arrangement of the latter it is seen that the link is driven by an eccentric on the main shaft; this shaft is termed a "crank axle," because part of it is shaped to form two cranks to which the main rods of the two low-pressure cylinders (one on either side) are connected, and as the entire gear of the low-pressure, or second expansion, engine,—of the cylinders and valves, both are inside of the frame, it was clearly necessary that the eccentric should be placed on the crank axle inside the frame, with sheave and strap exactly like the Stephenson eccentric, except, of course, that but one eccentric is used for each link. Outside of the frame the return crank on the main-pin actuates the valve gear of the high-pressure engine, which is the only part that can be seen in the photoengraving Fig. 16.

At this date the most powerful passenger engine ever built is the one depicted in Fig. 19, a recent production of the American Locomotive Company for the Lake Shore & Michigan Southern Railroad, and of which some of the principal dimensions are appended; here, again, the Walschaert valve gear is in evidence; and the heaviest and most powerful switching engine in existence at this time, built for the same road by the

Dimensions.

Diameter of driving wheels, outside.

FIG. 20. Decapod Switching Locomotive with Walschaert Valve Gear.

The heaviest and most powerful switching engine.