Some Olservations on Steam- Eng'mes, 121 



mosphere, is to be worked by the action of steam upon the pis- 

 ton, then tlie working cylinder must, as usual in steam-engines 

 so worked, be furnished with a cover. In this case, whether 

 the engine is to be worked as a single or as a double engine, in- 

 stead of the communications usual in the engines in common 

 use, viz. for the alternate admission and condensation of steam 

 above and below the piston, the communications of my engine 

 are to the upper part of the working cylinder, and to the upper 

 part of the receiver ; the receiver in my engine answering to the 

 space below the piston in other steam-engines, so that when th^ 

 receiver is open to the condenser, and the upper part of the 

 working cylinder open to the boiler, the piston descends, and 

 vice versa. It may be proper to remark here, that though I have 

 described my receiver as containing- and siurounding the working 

 cylinder, because I prefer this arrangement, vet the receiver may 

 be a separate vessel connected with the working cylinder at the 

 lower part. It is aho j^roper to remark, that to prevent waste 

 of steam by unnecessary condensation, and to keep up the temr 

 perature of the oil, or other fluid body employed, the receiver 

 may be inclosed in a steam-case, or heat may be applied to it 

 externally. Lastly, whatever arrangement or mode of working 

 be adopted, there should always be some oil, or whatever other 

 fluid body may be used, above the piston, to the height of a few 

 inches, to prevent the passage of the atmospheric air or of the 

 steam downwards by the side of the piston ; and as the quantity 

 of oil, or other fluid body, above the piston, may deviate from a 

 given height by the working of the engine, means must be pro- 

 vided to restore it to the requisite height, as cocks, valves, oi 

 any suitable contrivance, regulated by a float or floats upon the 

 surface of the oil, or bv means of a pump or pumps, worked by 

 the engine itself, or otherwise. By the interposition of the oil, 

 or other fluid body, between the piston and the condenser as be- 

 fore descril)ed, all waste of steam, by passing the piston, is ef- 

 fectually prevented, and a consequent saving of fuel is effected. 



''N.B. As it is usual for the pistons of steam-engines to work 

 in steam-vessels of a cylindric form, I have in the preceding de- 

 scription, for the sake of perspicuity, spoken only of the piston 

 working in a cylinder; but the piston may work in a fom'-sided 

 or any other polygonal prismatic-formed vessel. 



" In witness whereof," &c. 



The accompanying sections (Plate II) which we have laid 

 down from Mr. Woolf 's Specification, will give those of our readers- 

 who may not be perfectly acquainted with steam-engines, a pretty 

 correct itlea of the arrangement and mode of working which he 

 has specified. 



Fig. 



