124 New Intprovements on Steam-Enghiei. 



safety-valve exposed to the atmosphere : for example, that 

 masses or quantities of steam of the expansive force of 20, 

 30, or 50 pounds the square inch of a common safety-valve, 

 will expand to 20, 30, or 50 times its volume, and still be 

 re>pcctively equal to the atmosphere, or capable of producing 

 a sufficient action against the piston of a steam-engine to 

 cause the same to rise in the old engine (with a counter- 

 poise) oF Ncwcomen, or to he carried mto the vacuous part 

 of the cylinder in the improved engines first brought into 

 tflect by Messrs. Boulton and VV^Ttt. 



In consequence of this discovery Mr. Woolf was enabled 

 to use his steam twice (if lie chose), and with complete 

 fcflect; nothing more being necessary than to admit high 

 Pteam, suppose of 40 pounds the square inch, into one cy- 

 linder, to work there by its expansive force, and then to 

 allow the same steam to pass into, and expand itself in, an- 

 other cvliridcr of forty times the size of the first, there to 

 work bv condensation in the common uay. Or with only 

 one cylinder, by admitting a proportionally small quantity 

 of high sicam into it from the boiler, ISJr. Woolf found 

 that he could cfi'ect a considerable saving in fuel. 



In this first improvement of Mr. Woolf, though the 

 saving might be carried a considerable length, it was still 

 necessarily limited by the strength of materials ; for in the 

 eruployment of high steam there must always be some 

 danger of an explosion. Mr. Woolf, however, by a happy 

 thought, has completely obviated every danger of this kind, 

 end can now take the full advantage of the expansive prin- 

 ciple without the least danger whatever. This he effects by 

 throwing into common steam the additional temperature 

 necessarv for its high expansion, after the steam i.\ admitted 

 into the workhiif cijlhider, which is heated by mearis ade- 

 quate to the end intended to be obtained ; and the advantage 

 which he thus gains he effectually secures by a most inge- 

 nious improvement in the piston. It may be easily con- 

 ceived that steam of such high rarity as Mr. Woolf employs, 

 could not be made fully effective with the piston in common 

 wse ; for in proportion to its rarity so must be the facility 

 with which a portion of it would escape, and pass by the 

 ?ide of the piston to the vacuous part of the cylinder: but 

 Mr. Woolf 's contrivance seems pcrfccllv adapted to prevent 

 the loss of even the smallest portion of the steam. 



Besides these improvements on the common steam-en- 

 gine, he has also found means to apply the same principles 

 to the old engine, known bv the name of Savarv's, in such 



1* wav 



