Mr. Linnaker proposed two plans for propelling vessels by means of pumps: in the first the pumps were placed horizontally beneath the vessel's bottom, and in the second, a pump was placed vertically within the vessel, and communicated with two horizontal channels formed below the vessel's bottom. The first plan is shown by Fig. 1, which represents a section of the boat, and the propelling machinery, a a is the vessel, which is flat bottomed, b one of two rectangular trunks which extend one on each side of the keel the whole length of the bottom. In each trough is a rectangular plunger c, fitting the trough, and connected by the rods d d to the hanging levers e e. These levers are worked to and fro by the steam engine f acting upon the bell-crank lever g, the cross arms of which are connected to the levers e e by the rods h h; i is the condenser, and k the air pump, m the boiler, and n the funnel; o is a hanging valve, in the fore part of the trunk, and opening towards the stern. At each ascending and descending stroke of the engine, one of the plungers is thrust forward and the other backwards, and by the latter motion the water is drawn in at the valve o, and expelled at the hinder end of the trough.

Fig. 1.

Linnaker s Propelling Pumps 1808 610

Mr. Linnaker's second plan is similar in principle to the preceding, but the general arrangement is better, and more complete. It is shown in Fig. 2, which represents a transverse section of the vessel and propelling apparatus.

a a a a 's the frame of the vessel, which, as in the former instance, is flat bottomed, b and c two rectangular troughs formed below the bottom, and extending the whole length of the floor, d d is a large vertical pump communicating below directly with the trough b, and connected at the upper part with the other trough c, by the elbow pipe e; upon this pump is fixed a vertical steam engine f, and to the cross head of the piston-rod are attached two side rods g g, which pass through stuffing-boxes in the cover of the pump, and are attached to the piston h of the pump. The troughs are furnished at each end with a double set of hanging valves, so as to admit of reversing the motion of the boat, which is effected by merely turning a lever, which throws one set of the valves out of action, and puts the other set in operation.

Fig. 2.

Linnaker s Propelling Pumps 1808 611

The action of this apparatus will be readily seen; at each stroke of the engine the pump draws in water from the bows by the one trough, and expels at the stern water from the other trough, which by the reaction gives motion to the vessel.