In its original form there were some points that need alteration, as they certainly spoilt the general symmetrical effect of an otherwise artistic appearance. We may as well allude to these defects at once, and then proceed to detail the locomotive.

The first of such blots on the design was the placing of a cylindrical sand-box on the top of the boiler barrel, between the chimney and the dome. To show that such a position for this useful appendage was not necessary, we mention that only the driving wheels were supplied with sand from this unsightly excrescence, the supply of sand for the trailing wheels (for use when running bunker in front) being placed in an unobtrusive position. If the latter sand-boxes could thus be located, why was it necessary to place that for the leading wheels in so conspicuous a position? This example of awkward location of so useful an adjunct is further emphasised when we remember that these engines run just as frequently bunker first as chimney first. Further, in consequence of the position of this sand-box, the rod for working the sand valves was carried along the top of the boiler barrel, several inches above its surface, thus still more detracting from the symmetry of the design. The other feature we wish to allude to, is the shape of the dome cover, the whole of which was of a needlessly ugly contour. Then, again, in later years an enclosed cab was added, the back and front of which, being of sheet-iron, extending to the extreme of the coal bunker, and with no return sides, has given a rather toy-like appearance to these otherwise fine locomotives. We are glad to be able to mention that when these engines were rebuilt, the objectionable sand-box was removed, and a more pleasing form of steam dome provided, but this improvement was in a great measure negatived by the black enamelled iron which is now used for the cover in place of the bright brass formerly employed for the purpose.

Having thus mentioned the defects in appearance, rather than utility, of the North London Railway passenger tanks (Fig. 87), we can proceed to do justice to this really fine class of engines designed by Mr. Adams.

The outside cylinders were 17in. diameter, and the stroke was 24in. The driving and trailing wheels (coupled) were 5ft. 3in. diameter, the bogie wheels being 2ft. 9in. diameter. The heating surface was 1,015 sq. feet. The boiler was 4ft. 1in. diameter, and contained 200 tubes of 1¾in. diameter. A good feature in the design was the high steam pressure employed—viz., 160lb. per sq. in.—and there can be no doubt that much of the success of this class of engine can be traced to the use of so high a pressure of steam at a time—29 years ago—when other lines were using a much lower pressure. Indeed, to-day it is only necessary to watch a North London and any of several other railway companies’ trains starting side by side, and it will be observed that the North London generally gets away first; these engines are, in fact, capital at starting, and soon attain a high rate of speed.

The weight was as follows:—

It will be observed that, when empty, the bogie axles supported 19½ cwt. more of the gross weight than when the engine was in working order.

The wheel base of the bogie was 5ft. 8in. The coupled wheels have underhung springs connected by a compensation beam. India-rubber springs are used in connection with the hanging of the springs, and also to guide the bogie, etc., and it was found that such springs answered the use to which they were put in a most admirable manner.

In all the new engines that have lately been built, and when rebuilding old engines of this type, the cylinders have been increased to 17½in. diameter, and other things considerably modified in detail.

Mr. Pryce has also built 24 powerful six-wheel tank engines (Fig. 88) for dealing with the N.L.R. goods traffic. These engines are very efficient. They have outside cylinders 17in. diameter, 24in. stroke, and 4ft. 4in. coupled wheels. Boiler pressure, 160lb. per sq. in. Weight in working order, 45 tons 9 cwt., all available for adhesion. The total wheel base is 11ft. 4in.; consequently, they take curves easily.

The coal consumption of these engines was very satisfactory. The trains of the North London Railway consist of twelve vehicles, weighing, empty, 90 tons 14 cwt., and loaded 112 tons 6 cwt., but the coal consumption, with very frequent stoppages, only averaged 30.28lb. per mile.

Fig. 89 represents the combined saddle-tank locomotive and crane belonging to the North London Railway, as recently rebuilt by Mr. Pryce.