189 
Steam Engine. 
one- twentieth, or even larger, or of some intermediate 
proportion, may be employed instead of one of a fortieth 
of the capacity of the larger or working cylinder ; and so 
with steam of any other given strength. And it may be 
advisable, that in a number of engines this should be the 
case, because of the difficulty of preventing some v^aste of 
steam or partial condensation which might lessen the rate 
of working, if not allowed for in the size of the smaller 
cylinder or steam measure ; or in the quantity of steam 
admitted directly from the boiler into the working cylin- 
der, where no smaller cylinder or steam measure is em- 
ployed : and in every case the engine, when got ready 
for work, whatever may be the proportion that has been 
adopted as intended to be worked with, should have its 
power tried, by altering the load on the valve that ascer- 
tains the force of the steam, in order that the strength of 
steam best adapted for the engine may be ascertained ; 
for it may turn out to be advantageous that the steam 
should be employed, in particular engines of an elastic 
force, somew'hat over or under wdiat ^vas first intended. 
In witness whereof, &c. 
Since that Mr. Woolf has made other improvements 
of which the following is a brief view taken from VoL 23, 
p. 123, of Tilloch’s Mag. 
Account of Mr. Arthur Woolf’s netv Improvements 
on Steam-Engines. 
In our nineteenth volume, p. 133, we gave a short ac- 
count of a former improvement made by Mr. W oolf on 
the steam-engine, founded on a discovery that steam^, of 
any higher temperature than that of boiling water, if allovw 
ed to pass into another vessel kept at the same tempera- 
ture as the steam itself, will expand to as many times its 
volume, and still be equal to the pressure of the common 
atmosphere, as the number of pounds which such steam. 
