The Sun.
London, England, 1851-08-26 00:00:00

which at a pressure of 501 b. per square inch,
would require the evaporation of above seven cubic
feet of water per minute, or 420 cubic feet per hour,
being at the rate of evaporation of an ordinary sta-
tionary boiler of the nominal power of 420 horses.
This great evaporating power is obtained principally
by exposing a large heating surface to the action of
the furnace, and partly by stimulating the furnace by
great force of draught. The heating surface consists
of—first, the surface of the firebox, which is expos,,d
to the direct action of the heat radiating from the fuel
in combustion ; and secondly, the surface of the tubes
which traverse the boiler, and by which the heated air
is conducted from the firebox to the smokebox. These
tubes are all below the level of the water in the
boiler, as is also the entire heating surface of the fire-
box. The tubes are so regulated in number and
magnitude that when the heated air proceeding from
the combustion has passed through them, nr,d arrived
at the smokebox, it is reduced nearly to the tempe-
rature of the boiler, and is thus, as it were, strained of
its heat.

A draught of intense power is maintained through
the firebox by discharging the steam which proceeds
from the cylinders, after it has driven the pistons,
through a pipe called the blast pipe, which is pre-
sented upwards in the chimney. Each successive
cylinder-ful of steam, after it has driven the piston,
escapes through a pipe of communication from the
cylinder to the chimney, and rushes through this blast
pipe with the coughing noise already mentioned,
which is heard distinctly enough when the engine
first begins to move.
The preceding observations are applicable generally
to all the locomotive machines which will be found in
the Exhibition. .We shall now notice these engines
individually.
The most conspicuous among them will be found to
be three stupendous engines—two of which are exhi-
bited by the North-Western, and the third by the
Great Western Railway Company.
The North-Western Company exhibits a locomo-
motive engine on a gigantic scale, called " the Liver-
pool," constructed by Mesers. Bury and Co. This
vast machine is constructed on the principle
of the Crampton patent, the peculiarity of
which is, that the driving wheels are placed at the
rear of the engine immediately under the firebox.
This immense machine is supported on eight wheels,
the driving wheels being eight feet, and the support-
ing wheels four feet in diameter. The cylinders are
18 inches diameter, and 24 inches stroke. Tne eva-
porating power of the boiler must be enormous,
since the heating surface exposed to the direct action
of the fire is 156 square feet, and the total surface
of the tubes which traverse longitudinally the
boiler, and by which the gaseous products of combus-
tion are conducted from the firebox to the chimney,
and strained of their heat en route, have a total sur-
face of not less than 2,090 square feet. Thus there
is a total heating surface of 2,400 square feet. The
weight of the machine when supplied with its full
complement of coke and water is 37 tons.
The second engine exibited by the North-Western
Company is " the Cornwall," designed by M. F.
Trevithick, one of the superintendents, and con-
structed at the Crewe establishment of that company
in 1846, for the purpose of running express trains at
a high rate of speed. The cylinders in this machine
are 171 inches in diameter, and 2 feet stroke. The
driving wheels are 8 feet 6 inches in diameter. This
increase of diameter is given to the driving wheels
with a view to obtain an increased speed with a
diminished wear, arising from too rapid reciprocation
of the pistons.
The cylinders in this engine are placed outside the
wheels. The centre of gravity is lowered by suspend-
ing the boiler under the driving axle. The driving
wheels are placed about midway in the length of the
engine, while the others, bearing a lesser weight, are
placed at the foremost and hinder ends ; this disposi-
tion of the wheels being found to be faveurable to the
motion on curves. Tne boiler has 1,046 feet of heat-
ing surface, with certain peculiarities of construction
and arrangement of the working gear which renders
it easily examined when running. The gross weight
of the engine in working trim is 27 tons. It is sup-
ported on 8 wheels, and has taken trains at speeds
varying from 60 to 70 miles an hour.
The Great Western Company exhibit a stupendous
engine, constructed at their works at Swindon, called
" The Lord of the Lies." The machine is one of the
ordinary class of engines which have been worked
for passenger traffic since 1847 by the Great Western
Company. It is affirmed that it is capable of driving
a train of 120 tons gross, at an average speed of GO
miles an hour, upon such gradients as those which
Prevail on the Great Western Railway, which, as is
well known, is nearly level. The evaporating power
of the boiler, when in full operation, is stated at
1,000-horse power, and the effective power of the
engine, measured by a dynanometer, is equal to 743
horses. Its weight, including coke and water, is 35
tons. Th tender attached to this machine weighs
nine tons, the 'tank contains 1,600 gallons of water,
and there is space for a ton and a half of coke, giving
a total weight, fuel and water included, of 17 tons
13 cwt. The surface in the firebox exposed to ra-
diant heat measures 156 square feet, and the heating
'
surface of the tubes measures 1,759 square feet.
The diameter of the cylinder is 18 inches, the stroke
2 feet, and the diameter of the driving wheels 8 feet.
It is estimated that the boiler is able to bear a pres-
sure of 120 lb. per square inch, and that its actual