«J|g GVf S1EA.M-ENGINCS, 



%U. Woolfs the "& wilii which the production of the" latter is accorri* 

 improvement* panied, not only to the boiler and other parts of the ma. 

 sines- chinery, but even to the lives of the workmen ; for fuch 



low fleam, or even water, (but in every cafe fleam is pre- 

 ferable,) being admitted into a fteam veflel or veflels, or 

 working cylinder or cylinders, kept at the requifile higher 

 temperature by the forementioned means, wilt there be ex- 

 panded in any ratio required, and produce an effect in the 

 working of the engine which cannot otherwife be obtained 

 but at a greater expenfe of fuel, or with the rifk of an ex- 

 plofion. By this means I can make ule of fteam expanded 

 in any required ratio, or of any given temperature, without 

 , the neceffity of ever having the fteam of any greater elas- 



ticity than- equal to the preflure of the common atmo- 

 fphere. 



*' Another improvement which I make ufe of in fteam- 

 engines confifts in a method of preventing, as much as 

 poffible, the paflage of any of the fteam from that fide of 

 the pifton which is acted upon by the faid fteam to the 

 other fide which is open to the condenfer; and this I ef- 

 fect, in thofe fleam-engines known by the name of double 

 engines, by employing upon or above the pifton mercury 

 or fluid metal, or metals in an altitude equal to the preflure 

 of the fteam. The efficacy of this arrangement will appear 

 obvious, from attending to what mud take place in working 

 fuch a pifton. When the pifton is afcending, that is, when 

 the fteam is admitted below the pifton, the fpace on its other 

 fide being open to the condenfer, the fteam endeavouring to 

 pafs up by the fide of the pifton is met and effectually pre- 

 vented by the column of metal equal or fuperior to it in preflure, 

 and during the down ftroke no fteam can poflibly pafs without 

 firft forcing all the metal through. In working what is called 

 a tingle engine a lefs confiderable altitude of metal is required, 

 becaufe the fteam always acts on the upper tide of the pifton. 

 For tingle engines, oil or wax, or fat of animals, or fimilar 

 fubftances, in futlicient quantity, will anfwer the purpofe, if 

 another improvement, which conftitutes part of my faid in* 

 vention, be applied to the engine, namely to take care that 

 la either the double or Angle engine fo to be worked, the 

 outlet that conveys the fteam to the condenfer fhall be io po- 

 filed, and of fuck a iize, that the fteam may pafs without 



forcing 



