172 
Steam Engine. 
employed to act on the piston, I use a piston so constructs 
ed as to admit steam round its periphery, and in contact 
with the sides of the steam vessel, thereby to prevent the 
external air from passing in between the piston and the 
sides of the steam vessel. In witness whereof, &c.^ 
I give no account of Mr. Trevethick’s engine, where 
the depressing force on the piston is a column of water, 
because this does not come under the description of a 
steam engine. An account of this engine may be found 
in 1 Nich. Jour. 8vo. Series 161. But it appears that 
Mr. Trevethick erected steam engines that worked with- 
out condensing the steam. The following account is 
sufficient to render them unpopular, though perhaps un- 
justly, 
Dreadful accident. On Thursday the 8th of Steptem- 
ber, a steam engine employed to assist m clearing the 
works from water at the tide-mills now erecting in the 
marsh between Greenwich and Woolwich, was blown up 
by the force of the contained steam. The explosion was 
as sudden and dreadful as that of a powder-mill, and was 
accompanied with a similar noise, which wa^ heard at a 
great distance from the place. The engine was on Mr. 
Trevethick’s plan, worked by the expansive force of 
steam only, without employing condensation as in the en- 
gines in common use. It was literally blown to pieces ; 
and we are sorry to state, that by the accident three peo- 
ple were killed on the spot, and three others, all that were 
there at the time, so much hurt that two of them are not 
expected to recover. It was a fortunate circumstance 
that the accident happened at a time when the other work- 
men were at dinner, or a much greater number might 
have Jost their lives. 
* This patent seems tome to forestall, in some degree, the im^ 
provement of Mr. Woolf, in working his steam twice over. I am-- 
enable to say, whether this patent has been in much demand. 
T. C. 
