This locomotive is the design of Mr. Henry F. Shaw, of Boston.

This engine has oscillating cylinders placed between the driving-wheels. Fig. 2 represents a section of one of these cylinders, from which it will be seen that each has two pistons and piston-rods, which are connected directly to the crank-pins. His invention is described as follows in his specification:

"Midway between each set of wheels, e and f, is located the oscillating steam-cylinder, g, having its journals, g' and g", supported in the stationary arm, h, which is secured in a suitable manner to the frame, c. To each cylinder, g, is secured or cast in one piece therewith a balanced vibratory beam or truss, i, as shown. Within the cylinder, g, are two movable pistons, k and k', Fig. 2, provided with piston-rods, l and l', and cross-heads, m and m', as shown.

"n n are slides for the cross-head, m, on the insides of one end of the truss or beam, i, and n' n', are similar slides in the other end of said truss or beam, for the cross-head, m'. To the driving-wheel, e, is attached a crank-pin, passing through the cross-head, m, and to the driver-wheel, f, is attached a similar crank-pin, F, that passes through the cross-head, m'. o is the slide-valve within the steam-chest, G, which slide-valve is operated forward and back by means of the valve-rod, o¹, the outer end of which is hinged to the upper end of the slotted lever, o², Fig. 1, that is hung at o³, on the end of the balanced and vibratory beam of truss, i, as shown. On the crank, F, is secured an eccentric, that works within the slot of the slotted lever, o², during the revolution of the crank, F, and in this manner imparts the requisite motion to the slide valve, o, to admit the steam into the cylinder, g, alternately between the pistons, k and k', and at the ends of said cylinder, g, so as to alternately force the pistons, k and k', from and toward each other, and thus, in combination with the vibratory motion of the truss, i, impart a rotary motion to the driving-wheels, e and f.



"The steam is admitted to and from the cylinder, g, as follows: When the pistons, k and k', are at the outer ends of their stroke the steam enters through the channel, p, back of the piston, k, and at the same time through the channel, p', back of the piston, k', and thus causes both pistons to move toward each other, the steam between them being at the same time exhausted through the channels, q and q', the former communicating with the exhaust, r, by means of the space, s, in the valve, o, and the latter communicating with the exhaust, r', through the channel, s', in the said valve, o. The steam that passes to the back of the piston, k, comes direct from the steam-chest, G, through the open end of the channel, p, the valve, o, being at this time moved to one side to leave the port, p, open. The steam is admitted to the back end of the piston, k', from the steam-chest, G, through the channel, s", in the valve, o, and from thence to the channel, p'. When the pistons, k and k', have reached their inner positions the live steam is admitted through the channels, q and q', direct from the steam-chest, G, to the former, and through the recess, s³, and channel, s', in the valve, o, to the latter, the exhaust steam back of the piston, K, passing out through the channel, p, to the recess, s, in the valve, o, and thence to the exhaust, r, the exhaust steam back of the piston, k, passing out through channel, p', and through channel, s", in the valve, o, and thence to the exhaust, r'.

"The valve-rod, o', is to be connected to a link and reversing lever as usual, such being, however, omitted in the drawings."

The advantages claimed for it are that "it is composed of very few parts, and it is very powerful on account of its having a separate steam actuating piston for each of its driving-wheels. It has great strength and resistance, owing to the fact that no pressure is exerted on the journals on which the steam cylinders oscillate, and all the pressure from the steam pistons is directly transferred to the crank-pins on the driving-wheels. The engine is perfectly balanced in any position during the stroke, and it may therefore be run at a much higher speed than the common engines now in use."