(220.)

Another improvement, having the same objects, and analogous to the preceding, has been likewise patented by Messrs. Maudslay and Field. This consists in the adoption of a cylinder of greater diameter, having two piston-rods P P′, as represented in fig. 129., of considerable length, connected at the top by a cross-head C. From this cross-head is carried downwards the connecting rod D, which drives the crank-pin E, and thereby works the paddle-shaft S. In this case the paddle-shaft is extended immediately above the piston, and the double piston-rod has sufficient length to be above the paddle-shaft when the piston is at the bottom of its stroke. This improvement is intended to be applied more particularly for engines for river navigation, the advantages resulting from [Pg469] it being that a paddle-shaft placed at a given height from the bottom of the vessel will be enabled to receive a longer stroke of piston than by any other arrangement now in use. A more [Pg470] compact and firm connection of the cylinder with the crank-shaft bearings is effected by it, and a cylinder of much greater diameter may be applied by which the expansive action of steam may be more fully brought into play; and a more direct action of the steam-power on the crank with a less weight of materials and a greater economy of space may be obtained than by any of the arrangements of marine engines hitherto used.

Fig. 128.

Fig. 129.