come the difficulty. These axle-boxes were introduced in the year 1876, and there are now nearly 700 of them in use on engines, with the result that, in addition to the improved running, a considerable saving has been effected in the wear and tear of the flanges of the wheel tyres. A number of the long 42-feet carriages in use on the London and North- Western Railway have also been fitted with the same species of controlling gear at each end, their rigid base being thus reduced from 32 feet to 16 feet, with the best results as regards easiness of running, and saving of wear and tear; and the steady running of these vehicles in the fast trains running between London and Edinburgh last year was very noticeable. The under-frames of these carriages are constructed of steel, which is found to give them greater strength and elasticity than iron.
In addition to the various types of engines enumerated in the Appendix, Mr. Webb has constructed, for certain special purposes in connection with the railway, some small engines for narrow gauge lines, in which the usual link motion is done away with, and the engine is reversed by a pair of spur wheels, one of these spur wheels being keyed in the driving axle, and the other, equal in diameter, being fixed in a counter shaft, on each end of which is a crank driving the two valve spindles. The spur wheel on the driving axle is a broad one, occupying the space between the two bearings, and the spur on the counter-shaft is a narrow one, and held in position on the shaft by a skew-key, so that, by traversing the narrow wheel across the face of the broad wheel on this key, the relative position of the counter or valve shaft with the driving axle is altered, and so the engine is reversed,
