IN our SUPPLEMENT No. 97 we gave a general elevation of a single boiler Fairlie engine, designed by Mr. G. P. Spooner, for working the Festiniog narrow gauge—1 ft. 11½ in.—railway. We now give detailed drawings. It will be seen that this is a double bogie engine, with steam cylinders attached only to the leading bogie. The bogies are connected as usual to a carrier frame by their centers, upon which an ordinary type of locomotive boiler rests, the leading bogie carrying the boiler and the trailing the tender part of the engine. The bogies turn on Adams' patent centers. The following are the principal dimensions: Boiler: Length of boiler, 7 ft. 7 in.; diameter of barrel outside, 2 ft. 7 in. Fire-box: Length outside, 2 ft. 7¾ in.; average height to crown inside from fire-bars, 2 ft. 10 in. Wheel base: Leading bogie, 4 ft. 6 in.; trailing bogie, 3 ft. 6 in. Tanks contain 380 gallons. The principal particulars are as follows: Cylinders, 9 in. diameter, 14 in. stroke; driving wheels, 32 in. diameter (solid cast steel); weight in steam, total, 15 tons; weight on leading bogie, 10 tons; weight on railing bogie, 5 tons. Coal box holds 9 cwt. coal; working load up 1 in 80, 40 tons, at fourteen miles an hour. The baffle plate in the fire-box door is cast hollow in one piece, and perforated on the inner side, with an adjusting slide on the outside to admit air. All the mountings—viz., the two whistles, injector steam cock, Widmark's waste water cock, steam gauge, and cylinder lubricating steam cock—are all fixed on one general brass mounting in front of the cab connected to the boiler. The steam-pipe connections are differently arranged to those in general use. As shown in the accompanying diagrams, the vertical movement is taken by an elbow joint A, attached at the other end to a ball joint, which latter is on a stiff pipe with a ball joint at each end, and not telescoping as usual. A B takes the vertical movement from B as a center, the lateral motion being taken by B C, with B as a center. Although B is a suspended center, so to speak, supported by A and C. this arrangement works admirably. It may be stated that Mr. Spooner does not now use packing between the ball joint rings, but compresses the top ring with spiral springs, as shown. The plan has been at work for several years with success. The usual train for the engine consists of

Coal cars weigh 24 tons, as above, or equal weight in empty slate trucks or coals in empty sate trucks. The train is often increased to 50 tons and sometimes reduced to lea than 46 tons, making an average of 45 tons for three trips per day of nearly fourteen miles each, up one in eighty, returning only on the down trip with passenger cars weighing 22 tons. The average distance run per day is eighty-five miles.—The Engineer.