The life of George Stephenson, railway engineer - Lighthouse ...

CHAP. XXII.] CONSTRUCTION OF THE " ROCKET." 265
up within it,* were contracted slightly below the area of the
steam-ports ; and before the engine left the factory, the water
rose in the glass tube three inches above the water in the bucket.
The other arrangements of the " Rocket " were briefly
these :—The boiler was cylindrical with flat ends, six feet in
length, and three feet four inches in diameter. The upper half
of the boUer was used as a reservoir for the steam, the lower
half being filled with water. Through the lower part, twenty-
five copper tubes of three inches diameter extended, which were
open to the fire-box at one end, and to the chimney at the other.
The fire-box, or furnace, two feet wide and three feet high, was
attached immediately behind the boiler, and was also surrounded
with water. The cylinders of the engine were placed on each
side of the boiler, in an oblique position, one end being nearly
level with the top of the boiler at its after end, and the other
pointing towards the centre of the foremost or driving pair of
wheels, with which the connection was directly made from the
piston-rod to a pin on the outside of the wheel. The engine,
together with its load of water, weighed only four tons and a
quarter ; and it was supported on four wheels, not coupled. The
tender was four-wheeled, and similar in shape to a wagon,—the
foremost part holding the fuel, and the hind part a water-cask.
When the " Kocket " was completed, it was placed upon the
Killingworth Railway for the purpose of experiment. The new
boiler arrangement was found perfectly.- successful. The steam
was raised rapidly and continuously, and in a quantity Which
then appeared marvellous. The same evening, a letter was
dispatched to George Stephenson at Liverpool, informing him,
to his great joy, that the " Rocket " was " all right," and would
be in complete working trim by the day of trial. The engine
was shortly after sent by wagon to Carlisle, and thence shipped
for Liverpool.
* The alteration afterwards made in the blast of the " Eooket," after the
competition at RainhUl, by which the two separate exit pipes were thrown into
one, as in the original KtUingworth engines, was adopted rather with the view of
lessening the space occupied by them in the chimney than because of any
increased eifeot thereby secured, though it is probable that the jet of steam is
rather more efficient when thrown upwards in the exact centre of the chimney
than when slightly on one side.
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