174 
Steam Engine. 
gree of expansive force than can ever in any case be re- 
quired, has been lately invented by a very able engineer, 
Mr. Woolf. It consists of a combination of cylindrical 
tubes, which unite the double advantage of exposing a 
much larger surface to the action of the fire than the com- 
mon boiler, while they possess a much greater degree of 
strength. This invention appears to us so important, 
that we shall take an early opportunity of laying a de- 
scription of it before the public. 
The latest and most important improvements are con- 
tained in Mr. W oolf ’s patent for his steam engine. 
A short Account of^ix. Arthur Woolf’s improvement in 
the Construction of Steam Engines. 
Mr. 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 
w orld is indebted to Mr. Watt, who has been the princi- 
pal 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 
expanding 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 
tq 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 respec- 
tively 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 Newcomen, or to be carried into the vacuous 
