An engine working by the pressure of the atmosphere, a partial vacuum being obtained by the combustion of hydrogen gas in a close vessel. The first person who proposed obtaining power by this means we believe to have been the late Mr. Cecil, of Cambridge, who published some account of his plan, the details of which we do not rightly recollect In 1824 Mr. S. Brown took out a patent for an engine upon this principle, and at that time the invention excited considerable interest, and was by many looked upon as likely to supersede the steam engine; but although the inventor has since been perseveringly employed, and at a great expense, to bring the machine to perfection, we apprehend he has met with no great success, as the only instances in which we have heard of it being brought into actual use was on one occasion for raising water on the Surrey Canal, at Croydon, and at another time for a similar purpose, upon a canal in Oxfordshire; and very contradictory stated ments prevailed respecting the performance of the engines upon these occasions.

The preceding engraving represents the engine as constructed for raising water, which, by being led on to a water wheel, may also impart a rotatory motion to machinery; but this latter purpose may be effected by means of pistons working in cylinders. The method of producing the vacuum is as follows: - inflammable gas is introduced along a pipe into an open cylinder or vessel, whilst a flame placed on the outside, but near to the cylinder, is kept constantly burning, and at times comes in contact with the gas therein, and ignites it; the cylinder is then closed air-tight, and the flame is prevented from coming in contact with the gas in the cylinder. The gas continues to flow into the cylinder for a period, and is then stopped off; during that time it arts by its combustion on the air within the cylinder, and, at the same time, a part of the rarefied air escapes through one or more valves, and thus a vacuum is effected; the vessel, or cylinder, is kept cool by water. The two cylinders c and d are the vessels in which the vacuum is to be effected; from these descend the pipes gig and hjh, leading into the lower cylinders xx, from which the water rises along those pipes to fill the vacuum cylinders alternately.

The water thus supplied is discharged through the pipes B into the tank or trough Z, whence it falls upon the overshot water wheel, and by the rotatory motion thus produced, gives power to any machinery which maybe connected with it. The water runs from a wheel along a case surrounding the lower half into a reservoir v, from which the lower cylinders xx axe alternately supplied. In order to produce the vacuum, the gas is supplied to the cylinders by means of the pipe kick attached to a gasometer. The gas also passes along the small pipe 11 (communicating likewise with the gasometer), and being lighted at both ends of that pipe is kept constantly burning for the purpose of igniting the gas within the cylinders. The water in the reservoir v passing down one of the pipes w into one of the lower cylinders x, causes the float y in that cylinder to rise, and pushing up the rod o raises the end b of the beam, which of course draws up with it the cap f, and forces down the cap e of the other cylinder c. The gas being admitted along the pipe k, the flame from the pipe l is now freely communicated to the gas in the cylinder, through the orifice, by the opening of the sliding valve s, which is raised by the arm r, lifted by the rod o by means of the beam.

To produce the intermitting action of each cylinder, some intermediate machinery is put in operation by chains and rods attached to a glas3 or iron vessel p, partly filled with mercury, and turning upon a pivot; each end receives its movements of elevation and depression from the rise and fall of the projecting arms q, by the action of the beam above, the mercury being employed for the purpose of regulating the supply of gas into the cylinders, and the movement of the slide in the trough v. By the action thus communicated the water from the reservoir flows down the pipe w into the vessel x, and produces the elevation of the float y and of the rod n, and raises the cap e by the ascent of the beam at a. The motion thus caused in this part of the machinery acting upon its duplicate parts on the other side, of course produces by its action a corresponding movement, and the slider in the trough v, moved by the action of the mercurial tube p being moved from its position, allows the water to fall into the pipe w, and as it ascends, suffers the float y to descend, and rising into the main cylinder, thus lifts again the beam at b and its connexions, and forces down the cap e on the top of the other cylinder.

After the vacuum is effected in the cylinders, the air must be admitted to allow the water to be discharged, and the caps to be raised; this is accomplished by means of a sliding valve in the air-pipe m m, acted upon by chains 11 attached to floats in the reservoir, and as motion is given to them, the valve is made to slide backwards and forwards, so as to allow of the free admission of atmospheric air. Chains u u with suspended weights open the cocks in the pipe k k, and produce the alternate flow of the gas, and regulate and modify its supply. In the pipes gig and hj h, are docks to prevent the return of the water when the air is admitted into the cylinders.

Gas Vacuum Engine 547