the heating surface is, in the tubes, 1,112; fire box, 104;
total, 1,216 sq. ft. The weight of the engine in working order is 42 tons.

[Illustration: FIG. 7.--MIDLAND RAILWAY.]

The Midland Railway route to the North is distinguished by the heavy
nature of its gradients; between Settle and Carlisle, running through the
Cumberland hills, attaining a height of 1,170 ft. above sea level, the
highest point of any express route in the kingdom; and to work heavy fast
traffic over such a line necessitates the employment of coupled engines.
The standard express locomotive of this company has inside cylinders 18
in. in diameter and 26 in. stroke. The coupled wheels are 6 ft. 9 in.
diameter, and the leading wheels 4 ft. 3 in., the total wheel base being
16 ft. 6 in., and the tractive force 104 lb. for each lb. of mean cylinder
pressure. The boiler is of best Yorkshire iron, 10 ft. 4 in. long and 4
ft. 1 in. diameter. The grate area is 17.5 square feet, and the heating
surface is, in the tubes, 1,096; fire-box, 110; total, 1,206. There are
double frames to give outside bearings to the leading axle, as in the
Great Western engine, and the engine is fitted with a steam brake. The
weight in full working order is--leading wheels, 12 tons 2 cwt.; driving
wheels, 15 tons; trailing wheels, 11 tons 6 cwt.; total, 38 tons 8 cwt.
The tender weighs 26 tons 2 cwt., and holds 3,300 gallons of water and 5
tons of coal. Latterly a fine type of bogie express engine has been
introduced, with inside cylinders 18 in. diameter and 26 in. stroke, and
four coupled driving wheels 7 ft. diameter. The total wheel base to the
center of the bogie pin is 18 ft. 6 in. The grate area is 17.5 square
feet, and the heating surface is, in tubes, 1,203 square feet, and
fire-box, 110; total, 1,313; and the engine weighs 42 tons in working
order. These engines take fourteen coaches, or a gross load of 222 tons,
at 50 miles an hour over gradients of 1 in 120 to 1 in 130, with a
consumption of 28 lb. of coal per mile. The London, Chatham, and Dover
Company has also some fine engines of a similar type. They have inside
cylinders 171/2 in. diameter and 26 in. stroke; the coupled wheels are 6 ft.
6 in. diameter, and the bogie wheels 3 ft. 6 in., the wheel base to the
center of the bogie pin being 18 ft. 2 in. The boiler is 10 ft. 2 in. long
and 4 ft. 2 in. diameter, the grate area is 16.3 square feet, and the
heating surface is, in the tubes, 962 square feet; fire-box, 10