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200 rises to the upper part or ceiling of the room, and would escape if there were any outlet for it. But in most of our private dwellings there are none to be found. Builders seem to suppose that the fireplace, with the chimney, is the only ventilator necessary. This supposition is decidedly incorrect. The greater part of the air which goes up the chimney is drawn from the lower stratum of air in the room from which is coldest and purest portion, leaving the hot and impure air to collect in the upper part of the The Atmospheric Bude-Light remedies this important defect. It is always fixed high up in the room, with a large escape-pipe over it, leading to the chimney, which entirely carries off the products of the combustion of the gas. Without this pipe it is considered that London gas cannot be pleasantly burnt in the rooms of private dwellings.

, the inventor of the rotary engine, which it is the purpose of this short notice to describe, has endeavoured for the last twenty-five years to obtain that which has ever been considered an important desideratum, viz, a perfectly steam-tight rotary engine, subject in all its parts to comparatively little friction, and capable of revolving at very high velocities.

An engine of Mr. Beale's last construction is in daily operation at his engineering works, at East Greenwich. The outer cylinder of the engine measures 14 inches in diameter, and 94 inches long, internally. The piece serving as the piston is a cylinder of 12 inches diameter, placed excentrically within the former of 14 inches, so that the two cylinders nearly touch at one part, and are 2 inches distant at the opposite point; the mean transverse area of the excentric annulus being 14 square inches. The piston has 4 segmental indents, for the reception of as many rollers, each of 4 inches in diameter, and 9 inches long, which rest in contact with one side of the respective indents, and with the interior of the great or stationary cylinder, and divide the annulus into four chambers. The steam enters by a pipe from the boiler at top of the engine, and passing down the left-hand or ingress channel impinges against part of the roller which is nearest to the bottom of the channel; the roller is thus moved forward with a rolling motion in contact with the inside of the cylinder, and having passed the egress passage in the opposite side of the cylinder, the escape of the steam commerces, either into the atmosphere or into the condenser, as the case may be. The engines are generally formed with three or four rollers acted upon in turn, and so a continuous rotary motion is produced; and the power is given off by