and E, and for opening and shutting the said pallets or gates, CC, is so nearly similar to that of common engines, tha it would be useless to describe it further than that the said valves D and E require to be opened and closed at the same time, whereas, in general, they are opened and shut alternately by the plug tree, or other simple and wellknown means. F, the top of the cylinder, composed of a ring of metal, for pressing the packing round the moveable cylinder; the lid is screwed down with screws, as is usual in securing the lids or tops of cylinders. G G, two rings of metal pressed by screws, from a lever secured to the top of the cylinder F, for compressing the packing, and securing the joint of the cylinders A B. HH, a circular channel, into which the revolving cylinder B works, for the purpose of preventing the ingress of air or other fluids into or by the said interstice or channel, and which is packed with hemp and grease, and pressed in such a manner with a ring as thereby to render the engine more efficient, by keeping it perfectly tight. 1, the common condenser, the air pump of which is wrought by studs or stops projecting from the horizontal shaft, or any other simple or effectual way, which the engineer may think proper, as is more distincly seen in fig. 3, which is the end view of the shaft, and the side view of the piston rods; the operation of which is so obvious, as not to require elucidation. Fig. 2 exhibits a bird's eye view of fig. 1, with the top of the cylinder and compressing rings removed, to show the operation or apparatus for opening and closing the pallets, gates, &c. and also part of the flanges removed to show the situation of the valves. The letters of reference in this case of fig. 2, are placed upon the same parts of the engine as in fig. 1, which it would be superfluous to recapitulate. CC, the pallets, &c. formed of two or more pieces of metal; one part of the said pallet is permanently secured to each cylinder A and B, whilst the other part or parts turn on a joint or hinge; which said joint or hinge is made steamtight or secured, together with the whole of the edges coming in contact with the cylinder, with a hempen cloth stuffed wadded, or folded together, or by other similar

materials, capable of stopping the passage of steam, and which must be screwed or otherwise fastened on the front of the said pallet; and by the pressure of the steam it is pressed or brought in contact with the said pallet or cylin ders, and thus it effectually prevents the escape of steam or other fluids, by or with which the engine is wrought. K K, two racks and pinions communicating by a straight and parallel bar, working through a stuffing box in the sides of each cylinder, whereby the said valves are opened and shut, whilst passing each other, from the external part of the engine, by a piece projecting from the upper or lower part of the fixed cylinder, which may be placed at the option of the engineer; which said piece in its passage comes into contact with the gear connected with the said pallets, and thereby with any of the well-known simple methods or gear used for the opening and shutting of valves in the present steam engines. The gates, &c. of the engine are opened and shut as occasion requires. L, (fig. 2,) exhibits a second gate, &c. which in this case slides backwards against a straight parallel surface during the time the pallet in the revolving cylinder is passing, when the said gate is sliding by the gear against the revolving cylinder, as in the drawing. The said gates may be opened and closed in a variety of ways, such as a spindle ground into the bottom of the fixed cylinder, and connected by a link to the gate internally, or a crank or compound lever may be applied, instead of the rack and pinion, externally.

In another plan, Mr. Wilcox proposes a piston firmly fixed to the interior cylinder, and, instead of gates or pallets, he has a plate of metal, which is drawn into a recess as the piston passes, and returned immediately into the cylinder, so as to become an abutment for the action of the steam.

In this plan, A is the outside stationary cylinder. B, the inner cylinder; C, the top of the cylinder and rings, as in figs. 1 and 2, already explained. D, a plate of metal, as represented by the dotted lines, made very straight, smooth, and parallel, as it respects its thickness. E, a small shaft or axle, working through a box, or a receptacle fixed on

the outside of the cylinder A, allowing room sufficient for the said plate to drop clear off to the bottom of the cylinder, whilst an accurate incision is made in the bottom and side of the cylinder, sufficient to admit the said plate D to slide freely up and down, which is effected by a rack and pinion, or lever, or any other simple contrivance attached or connected to the extremity of the shaft E; by which means the steam is caused to act on the same or a similar principle, as in fig. 1. F, (fig. 4,) presents a second way of producing the same effect, namely, that of raising a plate of metal through an incision made in the bottom of the cylinder A, from a box fixed underneath the cylinder, through the medium of a parallel bar working through a stuffing box, whereby the said plate D is raised or depressed, as the working of the engine requires.

66 Fig. 5, is a bird's-eye view of fig. 4, with the same general letters of reference to their respective parts, as in fig. 4. K, the steam passage. L, a passage leading or communicating with the condenser, when the steam is required to be condensed. Here it may be necessary to remark, that, although the plate D be shown as rising upwards, considering it to be the most convenient way, nevertheless, the boxes necessary to receive the plates may be placed above the cylinder, and the plates may be raised in an oblique instead of a perpendicular direction.

"Fig. 8, is the plan of another rotatory engine. A, the outside fixed cylinder. B, the inner or revolving cylinder. D D, two or more pallets, working through a deep stuffing box, and turned by a lever, or other power, from the external part of the engine, alternately flat or edgewise; the piston F is fixed to the revolving cylinder; E, is the steam passage, that to the condenser not being shown.

"Fig. 10, is a bird's-eye view of a rotary engine, as wrought with a cock or portion of a circle, whereby a similar effect is produced as in fig. 1, by or with a portion of circles: in these figures, 8 and 11, the lids of the cylinders are removed, and a part of the flanges, where the circles or irregular cocks are used, is broken off, to render the working parts conspicuous. A, the outer or fixed cylinder.