The annexed figure represents a Direct-action Engine, which in appearance greatly resembles the preceding, the small side-beams being retained; but solely for the purpose of working the pumps. It was applied by Mr. David Napier, of Glasgow, to the "United Kingdom" steam-vessel, at a period when it was considered as of great dimensions.
In the annexed engravings, Fig. 1 represents an end view of the two engines, and Fig. 2 a side view of one of them.
The cylinders a a are of cast iron, and fixed to a framing, which is bolted to the bottom of the boat. The piston-rods b b are keyed at the upper ends to the cross-heads c c; to the exterior ends of which are attached the connecting-rods dd. The lower ends of these connecting-rods are inserted in the fork ends of the beams e e, which vibrate upon a shaftf, the bearances of which rest upon the top of the condenserg. In the same forks are inserted the ends of other connecting-rods h h, which are keyed at their upper ends to cross-heads ii. In the centre of these cross-heads are bosses large enough to receive the rodsjj, which extend to the crank pins of the cranks k k. These cranks are fixed to the main shaft, which rests upon the bearances ll, upon the arches m, which are bolted to the cross-beam, as at n. The shafts are shown as broken off at the outer ends, but they extend to the outside of the paddle-wheel.
The side beams e e are not straight, but have two bends, represented by the lighter parts of the shading; the ends near the cylinder being therefore much farther apart than the opposite ends, so that they may take up as little room as possible, by lying close to the respective parts of the machinery. They are also forked at the end nearest the air-pump o, so as to admit the insertion of the pump-rods p, which are connected at their upper ends to the cross-head q, in a bush, in the centre of which is keyed the air-pump rod r. Connecting-rods s are attached at t to the side-beams e, and at their upper ends to cross-heads, which are connected, as at u u, (Fig. 1,) to two rods, which work the plungers of two feed-pumps v, for supplying the boiler, j is the apparatus for blowing through, previous to starting the engine. It consists of a cock, which opens or closes a communication between the steam-chest and condensers, by turning the handle. The rod and lever x are for the purpose of regulating the quantity of injection water which enters into the condenser, by a pipe from the outside of the vessel, and can be increased and lessened in quantity by turning a cock to which the rod x is attached; y is the hot-well, into which the condensing water is discharged from the air-pump. The feed-pumps are supplied with water from this hot-well, through the medium of a pipe, the overplus being discharged through the side of the vessel by another pipe which is not seen.