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  Brake blocks of cast iron have now generally superseded wood; steel is being more and more used, especially on the North Western.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 brighter and can easily be kept clean.  There is greater simplicity of design generally, and the universal substitution of coal as coke for fuel, with its consequent economy; and last, but not least, the adoption of standard types of engines, are among the changes which have taken place in locomotive practice during the past quarter of a century.

[Illustration:  FIG. 8.—­LONDON, CHATHAM, & DOVER RAILWAY.]

[Illustration:  FIG. 9.—­GREAT EASTERN RAILWAY.]

[Illustration:  FIG. 10.—­MANCHESTER, SHEFFIELD, AND LINCOLNSHIRE RAILWAY.]

Having now reviewed, as far as the limits of this paper will allow, the locomotive practice of the present day, the author would in conclusion draw attention to what may possibly be one course of locomotive development in the future.  Time is money, and it may be in the coming years that a demand will arise for faster means of transit than that which we possess at present.  How can we meet it?  With our railways laid out