Improvements in the Construction of Steam-Engines. 1 33 



those places where the empire of fire has prevailed. We 

 are desirous, above all, that he should examine the basalte3 

 of Auvergne, which M. Leopold Buch, another pupil of 

 Werner, has visited, and among which he observed some 

 the volcanic origin of which he could not venture to dis- 

 pute. C. Daubuisson knows how to observe ; we have a 

 proof of it in the works he has already published, were it 

 not furnished bv the memoir in question : and the attention 

 which his observations seem to us to deserve, cannot be tes- 

 tified to him in a manner more useful to science than by 

 encouraging him to continue them. 



(Signed) Hauy and Ramond. 



The class approves the report, and adopts the conclusions. 



(Signed) Cuvier, perpetual secretary. 





XXIII. A short Account of Mr. Arthur Woolf's Im- 

 provement in the Construction of Steam-Engines. 



JVlLr. Woolf founds his improvements on a very im- 

 portant discovery which he has made respecting the expan- 

 sibility of steam when increased in temperature beyond the 

 boiling point, or 212° of Fahrenheit's thermometer. It 

 has been known for some time, and for this discovery the 

 world is indebted to Mr. Watt, who has been the principal 

 improver of the steam-engine, that steam acting with the 

 expansive force of four pounds the square inch against a 

 safety-valve exposed to the atmosphere, is capable of ex- 

 panding itself to four times the volume it then occupies, 

 and still to be equal to the pressure of the atmosphere. 

 Mr. Woolf has discovered that, in like manner, steam of the 

 force of five pounds the square inch can expand itself to five 

 times its volume ; that masses or quantities of steam of the 

 like expansive force of six, seven, eight, nine, or ten pounds 

 the square inch, can expand to six, seven, eight, nine, or 

 ten times their volume, and still be respectively 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 counterpoise) of Newcomen, 

 or to be carried into the vacuous part of the cylinder in the 

 improved engines first brought into effect by Messrs. Boul- 

 ton and Watt; that this ratio is progressive, and nearly if 

 not entirely uniform, so that steam of the expansive force 

 of 20, 30, 40, or 50 pounds the square inch of a common 

 safetv-valve will expand itself to 20, 30, 40, or 50 times it* 

 Vol. 1Q.. No. 74. July 1804. L I volume; 



