The old high-pressure engine of Richard Trevithick, which, thanks to Mr.
Webb, has been rescued from a scrap heap in South Wales, and re-erected at
the Crewe Works. We give engravings of this engine, which have been
prepared from photographs kindly furnished to us by Mr. Webb, and which
will clearly show its design.
[Illustration: TREVITHICK'S HIGH PRESSURE ENGINE AT CREWE.]
The boiler bears a name-plate with the words "No. 14, Hazeldine and Co.,
Bridgnorth," and it is evidently one of the patterns which Trevithick was
having made by Hazeldine and Co., about the year 1804. The shell of the
boiler is of cast iron, and the cylinder, which is vertical, is cast in
one with it, the back end of the boiler and the barrel being in one piece
as shown. At the front end the barrel has a flange by means of which it is
bolted to the front plate, the plate having attached to it the furnace and
return flue, which are of wrought iron. The front plate has also cast on
it a manhole mouthpiece to which the manhole cover is bolted. In the case
of the engine at Crewe, the chimney, firehole door, and front of flue had
to be renewed by Mr. Webb, these parts having been broken up before the
engine came into his possession.
The piston rod is attached to a long cast-iron crosshead, from which two
bent connecting rods extend downward, the one to a crank, and the other to
a crank-pin inserted in the flywheel. The connecting-rods now on this
engine were supplied by Mr. Webb, the original ones--which they have been
made to resemble as closely as possible--having been broken up. In the
Crewe engine as it now exists it is not quite clear how the power was
taken off from the crankshaft, but from the particulars of similar engines
recorded in the "Life of Richard Trevithick," it appears that a small spur
pinion was in some cases fixed on the crankshaft, and in others a
spurwheel, with a crank-pin inserted in it, took the place of the crank at
the end of the shaft opposite to that carrying the flywheel. In the Crewe
engine the flywheel, it will be noticed, is provided with a balanceweight.
The admission of the steam to and its release from the cylinder is
effected by a four-way cock provided with a lever, which is actuated by a
tappet rod attached to the crosshead, as seen on the back view of the
engine. To the crosshead is also coupled a lever having its fulcrum on a
bracket attached to the boiler; this lever serving to work the feed pump.
Unfortunately the original pump of the Crewe engine was smashed, but Mr.
Webb has fitted one up to show the arrangement. A notable feature in the
engine is that it is provided with a feed heater through which the water
is forced by the pump on its way to the boiler. The heater consists of a
cast-iron pipe through which passes the exhaust pipe leading from the
cylinder to the chimney, the water circulating through the annular space
between the two pipes.
Altogether the Trevithick engine at Crewe is a relic of the very highest
interest, and it is most fortunate that it has come into Mr. Webb's hands
and has thus been rescued from destruction. No one, bearing in mind the
date at which it was built, can examine this engine without having an
increased respect for the talents of Richard Trevithick, a man to whom we
owe so much and whose labors have as yet met with such scant
recognition.--_Engineering._
* * * * *
[Continued from SCIENTIFIC AMERICAN SUPPLEMENT, No. 451, page 7192.]