steam-tight passage, and, emerging at the other side, they are again turned to fill up the steam chamber. When pressed on one side by steam from the boiler, with a vacuum on the other, a very powerful continuous motion is generated. Mr. Moore's idea is a very ingenious one; and, could a mode be suggested of making the inner revolving drum steam-tight, without so great a loss of power as takes place in its present form, from the friction of so large a surface as the edges of his revolving cylinder, it appears capable of considerable precision in its action.*

The most simple and practical of all the projects for producing a rotatory motion by the weight of a column of fluid acting on the circumference of a wheel, is that proposed by Mr. Thomas Masterman in 1820.† In principle and arrangement, it is similar to Mr. Onions', but in every thing relative to simplicity of construction, convenience of arrangement, and effective action, it is beyond comparison better adapted to practice.

The Forty-seventh and Forty-eighth Figures

*

Repertory of Arts, vol. XL. page 194. Second Series. + Description of Masterman's Patent Rotatory Steam Engine.

London, 1822.

are vertical sections of this Steam Wheel. a, b, c, d, e, f, are weights at the ends of short levers, which open and shut the valves during the revolution of the wheel. s, s, is a steam-tight ring, divided into six or more compartments by the valves attached to the levers. Each of these chambers has a communication with a series of perforations surrounding the axis of the wheel, by the radiating arms or channels g h, i, k, l, m. This series of perforations revolves with the wheel against a fixed plate, which has three openings or perforations: one of these openings, p, leads to the condenser; n, to the boiler; and x, to the water cistern. a, is the axis on which the wheel turns, and by which motion is communicated to the other machinery. The valves a, b, c, &c. are moveable on a joint or hinge, and are connected by a spindle working steam-tight through the sides of the rim of the wheel, and attached to the weights already noticed.

The moveable series of perforations revolving with the wheel, are brought in rotation opposite each of the three perforations in the fixed plate; and each of the arms, and chambers in the circumference of the wheel, communicates in, turn with the condenser, water column, and boiler. In the position of the wheel shewn in the Figures, the moveable opening of arm h, is opposite to the perforation p, which leads to the condenser; arm 7, will then communicate with the water column by the perforation n. When steam from the boiler is allowed to flow through p,