Midland Railway it was found that a coupled engine with ten coaches at
fifty miles an hour made seventeen extra revolutions a mile, but when the
side rods were removed it made forty-three. The Great Western, Great
Northern, and Brighton mainly employ single engines for their fast
traffic; and the Manchester, Sheffield, and Lincolnshire have now adopted
the single type in preference to the coupled for their express trains;
while the North-Western, Midland, South-Western, and Chatham adopted the
coupled type. One noticeable feature in modern practice is the increased
height of the center line of boiler; formerly it was the great aim to keep
this low, and numerous schemes to this effect were propounded, but now it
has become generally recognized that a high pitched engine will travel as
steadily and more safely round a curve--given a good road--than a low
pitched one; and thus while in 1850 the average height of the center line
of boilers varied between 5 ft. 3 in. and 6 ft. 3 in., now in the latest
designs it lies between 7 ft. and 7 ft. 6 in. Single frames are very
generally adopted, but double frames and outside bearings to the leading
and trailing wheels, as in the Great Western engines, give great
steadiness in running, and this class has also double bearings to the
driving wheels, thus entailing greater security in case of the facture of
a crank axle. The general adoption of cabs on the foot-plate for the men
is another improvement of late introduction, although at first not
universally appreciated by those for whose comfort it was designed--"I
felt as if I was in my coffin," said an old driver when asked how he liked
the new shelter. Mild steel fire-boxes, which have been employed in
America, are not in favor here, copper being universally used; they have
been tried on the Caledonian, Great Southern and Western, North London,
and North-Western, and were found not to succeed. Brake blocks of cast
iron have now generally superseded wood; steel is being more and more
used, especially on the North Western. There is less use of brasswork for
domes and fittings, although it is claimed for brass that it looks