New Luproveiiienis 071 Steam-Engines, ig^ 



a way as to render the same a powerful and oecoaoinical 

 engine for a great variety of purposes. 



Such is the outline 'of Mr. Woolf's improvements on 

 this most useful engine : but, for the ireneral information 

 of practical engineers, we shall here subjoin a more tech- 

 nical description, in Mr. Woolf's own words, extracted 

 from his specification of his patent. 



" I have found out and invented a contrivance, by whidi 

 the temperature of the steam vessel or working cylinder of a 

 steam-engine, or of the steam vessels or cylinders where 

 more than one are used, may be raised to any required tem- 

 perature, without admitting steam from the boiler into any 

 surrounding receptacle, whether known by the name of a 

 steam case, or by any other denominaiion. That is to say, 

 instead of admitting steam of a high temperature into such 

 receptacle or steam case, which is always attended with 

 a risk of explosion proportioned to the' elasticity of the 

 steam employed, I put into the said surrounding receptacle, 

 or case, oil or the fat of animals, or wax, or other substances 

 capable of being melted by a lower temperature than the 

 heat intended to be employed, and of bearing that heat 

 ' without being converted into vapour : or I put into the said 

 case creases mercury or mixtures of metals, as of tin, bis- 

 muth, and lead, capable of being kept in a state effusion 

 in a lower temperature than that intended to be employed 

 in working the steam-engine; and I so form the surround- 

 ing case or cases as to make it or them admit the aforesaid 

 oil, or other substance employed, to come into contact not 

 only with the sides of the ste'am vessel or vessels, or work- 

 ing cylinder o^ cylindeis, but also with the bottom and top 

 of the same, so that the whole may be as much as possible 

 maintained at one uniform temperature; and this tempera- 

 ture I keep up by a fire immediately under or round the 

 case or cases that contains the aforesaid oil or other sub- 

 stance, or by connecting the said case or cases with a se- 

 parate vessel or vessels, kept at a proper temperature, filled 

 with the oil or other substance made use of as aforesaid. 

 In some circumstajices, or whenever the same may be con- 

 venient or desirable, I employ the fluid metals, or mixture; 

 of metals, and oil or other of the substances before enu- 

 merated, at one and the same time in the same engine: that 

 is to say, in the part of the case or vessel exposed to the 

 greatest action of the (ire, I sometimes have the afoj-esaid 

 metals or mixtures of metals, and in ihe parts less exposed 

 to the action of the fire, 1 put oil, or other substances ca- 

 pable 



