Fig. 90 represents the “Python,” one of J. Beattie’s four-coupled express engines, constructed for the L. and S.W.R. The cylinders were outside, 17in. diameter by 22in. stroke. The coupled wheels were 7ft. 1in. diameter, and the leading wheels 4ft. diameter. The heating surface was 1,102 sq. ft. Weight of engine in working order, 35 tons 11 cwt. For some years this class of engine was the favourite express engine on the L. and S.W.R.

Locomotive engineers have always one great difficulty to provide for—viz., the extra power required to start locomotives, especially on steep inclines, and as such grades are particularly en évidence on the mineral lines, it is not surprising to find Mr. W. Kendall, of Percy Main, Northumberland, patenting a locomotive designed to overcome the defects just indicated. The patent is dated October 26th, 1867. The engine was of the three-cylinder type, with one inside and two outside cylinders. When running on a level road only the inside cylinder was used, but for starting or ascending inclines the power of all three was brought into use, the whole arrangement of the power being actuated by the reversing gear apparatus. By a peculiar adaptation of the lap of the valves, a small quantity of steam was admitted to the valves of the outside cylinders when these cylinders were not working, for the purpose of lubrication. The engine in question was built at the Percy Main Works of the Blythe and Tyne Railway. She was of the “four-coupled behind” type, with a single pair of leading wheels. The inside cylinder was connected in the usual manner to the cranked axle of the centre wheels, the outside cylinders actuating the trailing pairs of wheels. Without diagrams it is rather difficult to explain the method employed to prevent the pistons, etc., of the outside cylinders from reciprocating, but shortly it may be stated that the connecting-rod was divided into two pieces, and at the joint each end fitted into an enclosed link. When disconnected, that portion of the rod coupled to the wheels which was in the link merely travelled up and down the link, whilst the part connected with the piston, etc., was at rest. By means of a screw gear this latter portion of the connecting-rod was lowered in the link, and engaged with the other part of the rod, which was coupled to the wheels, and so the outside cylinders were brought into action. If required, the outside cylinders could be used independently of the one inside cylinder, so that the engine could be a one, two, or three cylinder locomotive. Separate regulators were provided for the inside and outside cylinders, but the handles were coupled together, so that, if required, one movement actuated the admission of steam to all the cylinders. To prevent too strong a blast, the driver could, by the operation of a ball valve, discharge the exhaust steam from the outside cylinders into the atmosphere by means of a pipe in front of the engine. On the other hand, the whole of the exhaust from the three cylinders could be discharged up the chimney in the usual manner if preferred.

Upon April 13th, 1868, the Metropolitan and St. John’s Wood Railway was opened for traffic. The line branches from the Metropolitan Railway at Baker Street, and was worked by the Metropolitan Company. The gradients on the short line are very severe, and it was not considered advisable to attempt to work the railway by the usual type of engine employed on the underground line; so Mr Burnett, the then locomotive superintendent of the Metropolitan Railway, designed a special class of engine for the St. John’s Wood Railway. These were constructed by the Worcester Engine Company, and were numbered 34 to 38. They were provided with six coupled wheels of 4ft. diameter, with outside bearings; the cylinders were 20in. diameter, with a 24in. stroke; they were placed within the frames at 2ft. 2in. centres. The wheel base of these powerful locomotives was divided as follows:—L. to D., 6ft. 10in.; D. to T., 7ft. 2in. The boiler was 11ft. long, and 4ft. 3in. diameter, and contained 176 tubes of 2in. diameter.

The fire-boxes were exceptionally large, the measurements being: Length, outside 7ft. 1in., inside 6ft. 6in.; width, outside 4ft., inside 3ft. 6in. The depth was 5ft. 5in. in front, sloping to 3ft. 11in. at back. The steam pressure was 140lb.; heating surface, 1,165 sq. ft.; grate area, 22½ sq. ft. The water capacity of the tanks was 1,000 gallons.

These mammoth engines weighed 46 tons in working order, and it was soon discovered that they were far too powerful for working the light traffic over the St John’s Wood line, the ordinary type of Metropolitan locomotives being quite capable of successfully working the trains over these inclines. So, in 1873, when the Taff Vale Railway was in urgent need of some powerful engines for hauling the heavy coal trains over the Penarth Dock lines, the Metropolitan Railway succeeded in disposing of these five engines to the South Wales Company, and they can still be seen employed on work more adapted to their construction than was that of hauling light passenger trains on the St. John’s Wood Railway.

It is evident that both the patentee and builders of the “double-bogie” locomotives had a very exalted opinion of the capabilities of these peculiar engines. In December, 1870, G. England and Co. were advertising for sale by private tender to the best bidder “the most powerful locomotive at present known upon any railway in the United Kingdom, irrespective of gauge.”

This “most powerful” locomotive was constructed for the 4ft. 8½in. gauge on Fairlie’s double-bogie system. She had four cylinders, 15in. diameter and 22in. stroke, eight wheels, all drivers of 4ft. 6in. diameter, and with steel tyres.

Amongst other useful features claimed for this “most powerful” locomotive, we read that she “would take a load up an incline at a speed exceeding that of any other engine at present known, and would round the sharpest curves with ease.”

“Jinks’s Babies” consisted of a batch of ten engines constructed towards the end of 1871, and early in 1872. They had outside cylinders, 17in. diameter and 30in. stroke, with a leading bogie and four coupled wheels of 7ft. diameter; they had, perhaps, as good a right to the title “most powerful” as the Fairlie engine just mentioned.

Be this as it may, however, “Jinks’s Babies” were not successful. They were built at the Stockton and Darlington Locomotive Works, at Darlington, and originally numbered 238 to 240, etc., and upon the consolidation of the North Eastern Railway were renumbered 1238 to 1240, etc. They were rebuilt by Mr. Fletcher as six-wheel engines, the bogie giving place to a single pair of leading wheels, and the stroke of the pistons was reduced from 30in. to 26in. Even after this metamorphosis, “Jinks’s Babies” could not be truthfully described as successful locomotives. Amongst other peculiarities the circular valves should be enumerated. The steam pressure was 140lb. per sq. in.

In 1871 the Lancashire and Yorkshire Railway fitted up an engine with an apparatus said to have been invented by Mr. Richard Eaton, but called “Warsop’s Aero-Steam system,” by means of which a continuous supply of heated air was forced into the bottom of the boiler, so causing the water to be continually agitated, and thereby preventing incrustation of the metal, as well as more quickly generating steam, and last—but far from least—economising the fuel. The engine experimented upon was a six-coupled goods, No. 369, with cylinders 15in. by 24in., 5ft. wheels, and working at a pressure of 130lb. per sq. in. An air pump, single acting, 6in. diameter by 2ft. stroke, with piston and metallic rings, driven from one of the main cross-heads, was secured to the framework of the engine in the place originally occupied by the feed-pump. The compressed air passed along a pipe 1½in. in diameter, 6ft. long, to a coil of 1½in. lap-welded iron pipe, within the smoke-box, 61ft. in length, so arranged as to avoid contact with the blast pipe or the ashes deposited in the smoke-box by the action of the blast. After traversing the coil, the expanded air became heated to a temperature nearly as high as that of the waste gases, and thus ranging between 500 degrees and 800 degrees, or 850 degrees Fahr., lifted the self-acting valve, and entered the perforated distributing pipe within the boiler, and was constantly passing in jets through the water to the steam space, whence the combined powers of steam and air proceeded to the cylinders to carry out their duty. A very simple apparatus was used when desirable to stop compression, by keeping the inlet valve open when steam was shut off; otherwise an undue proportion of air would enter the boiler, and impede the feed-water injectors.

At the same time, occasions arose where a judicious use of the air injection was made with great advantage, even with steam shut off. It is stated that “on March 21st, 1872, there was a heavy fall of snow, and the driver of No. 369 had to make the most of his resources. In coming down Rainford bank he had but 100lb. of steam at Balcarres siding, with steam shut off. He allowed the air pump to continue work, and in 400 yards his gauge rose to 140, when he opened his regulator again to mount the incline with his heavy load, and so successfully gained the summit.” The annexed table shows the working of engine No. 369, with and without the apparatus, and also of an exactly similar engine, No. 38, employed on the same length of line, and hauling the same trains. No. 38 was not fitted with the apparatus.

Although the above glowing statement is made about this invention, which was fitted to no less than six engines, and tried for a period of about five years, it was not found to be commercially successful, the power consumed in working the pump, and the cost of repairs running away with the economy supposed to have been gained in the original experiment.

About this time the Furness Railway introduced a powerful design of six-coupled tank engines. The cylinders were: Inside, 18in. diameter and 24in. stroke; heating surface tubes, 1,048 sq. ft.; fire-box, 96 sq. ft.; grate area, 15 sq. ft. The frames were “inside.” The side tanks were capable of containing 1,000 gallons of water.

Weight in working order: L., 13 tons 13 cwt.; D., 16 tons 6 cwt.; T., 14 tons 15 cwt.; total, 44 tons 14 cwt. On the level this class of engine hauled 372 tons at 20 miles an hour, and up an incline of 1 in 80 a load of 367 tons was drawn at 11¾ miles an hour. The steam pressure was 145lb., and the coal consumption 40.16lb. per mile.

The name of Patrick Stirling, the late locomotive superintendent of the Great Northern Railway, will long be remembered and held in high honour amongst those of his confrères, consequent upon his successful design of 1870, in which year he built the first of his now world-famous 8ft. 1in. singles, a type of locomotive which immediately leaped into public favour, which for elegance and simplicity of design it is not saying too much in stating that no modern engine has surpassed or is likely to surpass. These engines soon showed the travelling public that really express speed could be safely indulged in for continuous runs of great length without fear of accident or failure. Indeed, modern express speed can date its foundation from the introduction of these engines. The Great Northern Railway undoubtedly owes its popularity and fame as the “express” route to the successful running of Patrick Stirling’s 8ft. 1in. outside cylinder “single” engines.

The following may be accepted as a correct description of the earlier type of this locomotive design. Later engines of the same class have, in common with the development of locomotive design, increased in weight, grate, tube, and cylinder area, and steam pressure; but the general outline to-day, as seen in Fig. 91, is the same as that of 27 years ago, and we do not think this compliment can be paid to the design of any other locomotive built at the present time. The cylinders were 18in. diameter, with a length of stroke of 28in. The small ends of the connecting-rods were furnished with solid bushes of gun metal. The inner and the outer fire-boxes were connected together by stays, screwed into each of the plates, without the intervention of iron girder bars. By this arrangement, which had been in use for some time in Belgium, the large amount of deposit generally existing upon girder-boxes was prevented, the facility for cleansing was much greater, and the liability of the tube holes in the copper-plate to become oval had been got rid of.

The heating surface in this engine was, in the tubes, 1,043, and in the fire-box 122 sq. ft. The fire-grate had an area of 17.6 sq. ft. When the engine was in working order, the weights upon the driving, trailing, and bogie wheels were 15, 8, and 15 tons respectively. The distance from the centre of the trailing wheels to the centre of the bogie pin was 19ft. 5in. These engines were capable of drawing a weight of 356 tons on a level at a speed of 45 miles an hour, with a working pressure of 140lb. to the sq. in. The consumption of coal, with trains averaging sixteen carriages of 10 tons weight each, had been 27lb. per mile, including getting up steam and piloting. The cost of maintaining and renewing passenger engines on the Great Northern Railway was in 1873 estimated to amount to 2½d. per mile.

The contemporary type of engines on the “West Coast” route was the celebrated “Precedent” class, illustrated by “John Ramsbottom” (Fig. 92).

These London and North Western Railway locomotives were constructed at the Crewe Works, from the designs of Mr. F. W. Webb, locomotive superintendent, the first of them being constructed in December, 1874. The engines, as our readers well know, have four-coupled wheels, 6ft. 6in. diameter, and a leading pair of wheels 3ft. 9in. diameter. The principal dimensions originally were—they may vary a little in some details in certain engines—inside cylinders, 17in. diameter, with a stroke of 24in. Heating surface, 980 sq. ft. in tubes, and 103.5 sq. ft. in fire-box; grate area, 17.1 sq. ft.; weight in working order, L., 10 tons 5 cwt.; D., 11 tons 10 cwt.; T., 11 tons; total, 32 tons 15 cwt. Steam pressure, 120lb.; wheel base, 15ft. 8in.

The most famous engine of this class is the “Charles Dickens,” No. 955, built at Crewe in 1882; the “Inimitable” is shedded at Manchester, and the daily journey to and from Euston consists of 366½ miles; the trains worked by this engine are the 8.30 a.m. up, and the 4 p.m. down. As long ago as September 21st, 1891, the “Charles Dickens” had obtained the premier position in engine mileage. On that day “she”—if the shades of “Boz” will allow the bull—completed her millionth mile, consisting, of 2,651 trips between Manchester and London, in addition to 92 other journeys. During this period of 9 years 219 days the engine had burned 12,515 tons of coal. Up to the end of February, 1893, the total mileage of “Charles Dickens” amounted to 1,138,557, and up to the present time it has exceeded the enormous total of 1,600,000 miles!

In April, 1874, Mr. Webb introduced another type of locomotive for the London and North Western Railway: the “Precursor,” No. 2145, gives its title to the design in question.

The cylinders were 17in. by 24in. stroke. The leading wheels were 3ft. 6in. diameter, whilst the driving and trailing wheels (coupled) were 5ft. 6in. diameter. The tubes contributed 980 sq. ft., and the fire-box 94.6 sq. ft., of the heating surface. The weight in working order was 31 tons 8 cwt.

“Firefly”, (Fig. 93) is one of the numerous six-wheel outside cylinder tank engines built from the designs of J. Beattie by Beyer, Peacock and Co. for the L. and S.W.R. between 1863 and 1875. The cylinders were 15½in. by 20in. stroke, the leading wheels 3ft. 7¾in. diameter, and the coupled wheels 5ft. 7in. diameter. The heating surface was 795.17 sq. ft.; the weight, in working order, 34 tons 12 cwt. A number of these engines had the cylinder diameter increased to 16½in, and a tender added by W. Adams in 1883. “Firefly” was built in 1871.

“Kensington” (Fig. 94), a L., B. and S.C. locomotive, was, in December, 1872, rebuilt by Mr. Stroudley in the form illustrated. The cylinders were 17in. by 24in. stroke; coupled wheels, 6ft. 6in. diameter; leading wheels, 4ft. 3in. diameter. In 1872, “Kensington” was domeless, that appendage being added later. This engine was originally a single engine, built by R. Stephenson and Co. in 1864. Altogether, this engine, like many individuals, has “played many parts.”

We have now reached a period in locomotive history when the engines to be described are of comparatively modern construction, a very large proportion of them being still in work on the various lines of railway, and readers interested in such matters are probably acquainted with the particulars of the locomotives. Under such circumstances, a detailed and particular account of each design would be rather wearisome, therefore the general features of modern engines will be less fully described. At the same time any uncommon points in their design or construction will be mentioned.

The standard type of express passenger engines now used on the South Eastern Railway has developed from a class introduced by Mr. J. Stirling, when locomotive superintendent of the Glasgow and South Western Railway.

In 1873 he constructed at the Kilmarnock Works an engine with a leading bogie and four coupled wheels of 7ft. diameter. The cylinders were inside, 18in. diameter and 26in. stroke. In this design, as in the later type on the South Eastern Railway, the boiler was unprovided with a dome, but in the latter the duplex safety valve is placed about the centre of the boiler barrel, whilst on the Glasgow and South Western Railway engines it surmounts a flush top fire-box.

Mr. Stirling’s reversing apparatus is a very useful contrivance; it enables the driver to reverse his engine without the expenditure of any muscular power. At first the new reversing gear was frequently mistaken for the Westinghouse air-brake pumps. It consists of two vertical cylinders placed tandem fashion at the side of the boiler barrel. One piston-rod passes through both cylinders, and the pistons are attached to it; this rod is connected with the reversing apparatus. One cylinder contains steam, the other oil. The duty of the latter is to prevent the movement of the piston or rod. It will be understood that, since the cylinder is quite full of oil, it is impossible for the piston and connections to move unless the oil can pass from one side of the piston to the other.

This is accomplished by a handle, which also actuates the valve of the steam reversing cylinder so that when the steam is admitted into one cylinder to move the piston, the oil is at the same time permitted to flow through a valve to the other piston, and the reversing apparatus is worked.

The oil keeps the piston in any desired position. As soon as the oil cannot pass from one side of the piston face to the other, the gear is firmly locked.

Mr. A. M. Watkin became locomotive superintendent of the South Eastern Railway in 1876, and he introduced a very pretty design of express passenger engines. Twenty engines of the type were constructed: Nos. 259 to 268 by Sharp, Stewart, and Co., and Nos. 269 to 278 by the Avonside Engine Company. Inside frames were provided; the leading wheels were 4ft. and the four-coupled wheels 6ft. 6in. diameter. The cylinders were 17in. diameter and 24in. stroke. The weight in working order was 34½ tons; the total heating surface, 1,103½ sq. ft. The splashers to the coupled wheels were of open-work design. The chimney was of the rimless South Eastern pattern; a dome was provided on the centre of the boiler barrel, and a duplex safety valve on the fire-box top. A cab very much resembling the standard London and North Western Railway pattern was fitted to the engines.

Several of these engines, as rebuilt by Mr. Stirling, remain in work at the present time; they are principally employed on the Mid-Kent services.

In 1874 Mr. Stroudley, the then locomotive superintendent of the London, Brighton and South Coast Railway, built the “Grosvenor” with 6ft. 9in. single driving wheels, inside cylinders 17in. by 24in., and a total heating surface of 1,132 sq. ft. The “Stroudley” speed indicator was fitted to this engine. On August 13th, 1876, the “Grosvenor” conveyed a train from Victoria to Portsmouth (87 miles) without a stop. This was the first occasion on which such a trip had been performed; the time taken was 110 minutes.

No other engine exactly similar to the “Grosvenor” was constructed; but in 1877 the “Abergavenny”—with 6ft. 6in. single drivers and cylinders 16in. by 22in.—was built, and in 1880 the first of the “G” class of singles was turned out at the Brighton Works. These also have single driving wheels 6ft. 6in. in diameter, but the cylinders are 17in. diameter, the stroke being 24in. The weight on the driving wheel is 13 tons.

An interesting era in the evolution of the steam locomotive is at this point arrived at—viz., the first really practical trial of compound engines, or the use of steam twice over for the purpose of propelling a locomotive.

To Mr. Webb, the chief mechanical engineer of the London and North Western Railway, is due the honour of introducing the compound system on an extended scale in railway practice. Although 21 years have now passed since the premier attempt of giving the system a fair trial on an English railway was made, it does not seem to have gained much favour with English locomotive engineers. Indeed, at the present time, excepting a few minor trials elsewhere, the London and North Western Railway is the only company that constructs and uses compound locomotives.

Mr. Webb employs the three-cylinder type of engine, which is an adaptation of the system introduced by M. Mallet on the Bayonne and Biarritz Railway. Three engines were built from Mr. Mallet’s design by Schneider and Co., Creusot, and were brought into use in July, 1876. In these locomotives Mallet employed two outside cylinders, one being 15¾in. and the other 9½in. diameter.

Mr. Webb uses three cylinders: an inside cylinder for the l.p. steam and two outside cylinders for the high-pressure steam. But at first one of Trevithick’s old “single” engines was fitted up on Mallet’s two-cylinder plan. This was in 1878. The engine worked successfully for five years on the Ashley and Nuneaton branch of the London and North Western Railway, and thereupon Mr. Webb decided to construct compound engines on his three-cylinder system.

The first of such engines was the “Experiment.” Her outside h.p. cylinders were 11½in. diameter, the inside l.p. being 26in. diameter. Joy’s celebrated valve gear was employed to regulate the admission of steam to the cylinders.

“Webb” compounds have two pairs of driving wheels, but these are uncoupled, so that practically the engines are “singles.” Whether the four driving wheels work well together, or whether, on the other hand, there exists a considerable amount of either slip or skidding is another matter. The trailing pair of wheels is driven from the h.p. cylinders, and the middle pair from the inside or l.p. cylinder.

Mr. Bowen-Cooke, an authority on London and North Western Railway locomotive practice, sums up the advantages of the “Webb” compound system under the five following heads:—

The 6ft. wheel type of London and North Western Railway compound was introduced in 1884. The outside cylinders are 14in. and the inside 30in. diameter, stroke 24in. Joy’s gear is used for all the valves; the valves to the outside cylinders are below, and the valve of the l.p. cylinder is above the cylinder. The boiler steam-pressure is 175lb. per square in., but it is reduced to 80lb. when entering the low-pressure cylinder. The weight of the engine in working order is 42 tons 10 cwt. Heating surface: Tubes, 1,242 sq. ft.; fire-box, 159.1 sq. ft.; total, 1,401.5 sq. ft. Grate area, 20.5 sq. ft.

An engine built to this design—the “Marchioness of Stafford”—was exhibited at the London Inventions Exhibition of 1885, and gained the gold medal.

In 1890 the first of the “Teutonic” (Fig. 95) class of 7ft. 1in. compounds was constructed at Crewe Works. The leading wheels of this type are 4ft. 1½in. diameter. Total weight in working order, 45 tons 10 cwt. In these engines Mr. Webb’s loose eccentric motion is used for the low-pressure inside cylinder, but Joy’s gear is retained for the h.p. outside cylinders.

Another type of compound is the “Greater Britain.” During 1897 the “Greater Britain” and other engines of the class were coloured red, white, and blue, and employed to haul the Royal train when travelling over the London and North Western Railway system. They were then nicknamed the “Diamond Jubilees.”

The special feature of this class is the length of the boiler, which is divided into two portions by means of a central combustion chamber. The heating surface is: fire-box, 120.6 sq. ft.; combustion chamber, 39.1 sq. ft.; front set of tubes, 875 sq. ft.; back set of tubes, 506.2 sq. ft. total, 1540.9 sq. ft. The two pairs of driving wheels are located in front of the fire-box, and in addition there are a pair of leading and a pair of trailing wheels.

An engine of this class—the “Queen Empress” (Fig. 96)—was exhibited at the World’s Fair held at Chicago in 1893. Her leading dimensions are: Two high-pressure cylinders, 15in. diameter by 24in. stroke; one low-pressure cylinder, 30in. diameter by 24in. stroke; wheels—driving, 7ft. 1in. diameter (four in number); leading, 4ft. 1½in. diameter; trailing, 4ft. 1½in. diameter. Weight on each pair of driving wheels, 16 tons. Total weight of engine in working order, 52 tons 15 cwt. Total wheel base, 23ft. 8in. Centre to centre of driving wheels, 8ft. 3in.

The most recent type of compound goods locomotives constructed by Mr. Webb has eight-coupled wheels, three pairs of which are located under the fire-box, the trailing pair being close to the back of the fire-box. The outside cylinders are below the top of the frame-plate, and incline towards the rear. This type of engine was designed by Mr. F. W. Webb, chief mechanical engineer of the London and North Western Railway, principally for working the heavy mineral traffic over that Company’s South Wales district, the first engine being built in 1893. The wheels (all coupled) are 4ft. 5½in. in diameter, with tyres 3in. thick. The distance between the centres of each pair is 5ft. 9in., the total wheel base being 17ft. 3in. All the cylinders drive on to one axle—the second from the front of the engine; the two high-pressure cylinders are connected to crank pins in the wheels set at right angles to each other, the low-pressure cylinder being connected to a centre crank-pin set at an angle of 135 degrees with the high-pressure cranks; the high-pressure cylinders are 15in. diameter by 24in. stroke, and the low-pressure cylinders are 30in. diameter by 24in. stroke. All the cylinders are bolted together and in line, the low-pressure being placed immediately under the smoke-box, and the high-pressure cylinders on each side outside the frames, the steam chests being within the frames.

The engine weighs, in working order, 53 tons 18 cwt.

The empty weights are as follows:—

The latest type of a passenger compound locomotive built by Mr Webb is the 7ft. four-wheels-coupled engine “Black Prince” (Fig. 97), which was built at the Crewe Works in July, 1897.

The engine has two high-pressure and two low-pressure cylinders, all being in line, and driving on to one axle, the high and low pressure cranks being directly opposite each other.

One of the features of this engine is the method adapted for working the valves, two sets of gear only being used for working the four valves.

Joy’s valve motion is used for the low-pressure valves, the valve spindles being prolonged through the front of the steam chest, and on the end of the spindle a cross-head is fixed which engages with a lever of the first order, carried on a pivot firmly secured to the engine frame. The other end of this lever engages with a cross-head fixed on the end of the high pressure valve spindle, and by this means the requisite motion is given to the high pressure valve.

The leading end of the engine is carried on a double radial truck, the centre of which is fitted with Mr. Webb’s radial axle-box and central controlling spring. This arrangement permits of 1in. side play, and gives greater freedom to the truck when passing round curves than is possible in the ordinary type of bogie with a rigid centre-pin.

One important object aimed at in the construction of this engine has been to get all the bearing surfaces throughout as large as possible. Each of the four journals in the radial truck is 6¼in. diameter and 1Oin. long. The driving axle, in addition to the two ordinary bearings, which are each 7½in. diameter and 9in. long, has a central bearing between the two cranks, 7in. diameter and 5½in. long. In the trailing axle the journals are 7½in. diameter, by 13½in. long.

This engine made its first trip on August 2nd, 1897, and since then has been principally engaged in working the “up” dining saloon express, which leaves Crewe at 5.20 p.m., running through to Willesden without a stop—a distance of 152½ miles—and returning the same night with the Scotch sleeping saloon express, which leaves Euston at 11.50 p.m., running through to Crewe without a stop, 158 miles.

The total distance run by this engine up to June 30th, 1898, was 52,034 miles.

The high-pressure cylinders are 15in. diameter by 24in. stroke, and the low-pressure cylinders are 20½in. diameter by 24in. stroke.

The heating surface is: Tubes, 1,241.3 sq. ft.; fire-box, 159.1 sq. ft.; total 1,409.1 sq. ft. Grate area, 20.5 sq. ft.

A concise survey of other compound locomotives will be of interest at this juncture.

Mr. Wordsell, the then locomotive superintendent of the Great Eastern Railway, in 1882 built a compound engine, with two inside cylinders, the h.p. 18in. and the l.p. 26in. diameter; the stroke was 24in.; steam pressure, 160lb. per sq. in. The coupled wheels were 7ft. diameter. The engine was fitted with a leading bogie, the wheels of which were 3ft. 1in. diameter; with her tender she weighed 77 tons in working order; her number was 230. A similar engine, No. 702, with Joy’s valve gear, was built in 1885.

Mr. Wordsell also built a two-cylinder, six-coupled goods engine for the Great Eastern Railway, on the compound principle. This was fitted with the ordinary link motion.

Mr. Wordsell, upon his appointment as locomotive superintendent of the North Eastern Railway, introduced compound engines on that line. These were provided with two cylinders, both inside, with the valves on top.

The h.p. cylinder is 18in. and the l.p. 26in. in diameter, the stroke being 24in. Mr. Worthington thus describes the North Eastern Railway standard compound goods engine:—“In outside appearance this engine is neat, simple, and substantial. It weighs 40 tons 7 cwt., and has six coupled 5ft. 1¼in. in diameter.

“The cylinders are placed, as in the passenger compound engines, beneath the slide-valves and inside the frames.

“The chief features of this goods engine to be observed are the starting and intercepting valves, which enable the engine-driver to start the engine by admitting sufficient high-pressure steam to the large cylinder without interfering with the small cylinder, in case the latter is not in a position to start the train alone.

“The two valves are operated by steam controlled by one handle. If the engine does not start when the regulator is opened, which will occur when the high-pressure valve covers both steam ports, the driver pulls the additional small handle, which closes the passage from the receiver to the low-pressure cylinder, and also admits a small amount of steam to the low-pressure steam chest, so that the two cylinders together develop additional starting power.

“After one or two strokes of the engine the exhaust steam from the high-pressure cylinder automatically forces the two valves back to their normal position, and the engine proceeds working compound.”

The North Eastern Railway has other compound engines constructed on the Wordsell and Van Borries system, a 6ft. 8¼in. four-coupled, with a leading bogie of locomotive, being turned out in 1886. Engines of this type have a heating surface of 1,323.3 sq. ft., a grate area of 17.33 sq. ft., and a working pressure of 175lb. per sq. in.

Another North Eastern Railway type of compound has 7ft. 6in. single driving wheels and a leading bogie. The h.p. cylinder is 20in., and the l.p. 26in. diameter, compared with 18in. and 26in. in the four-coupled class, the stroke being the same in each design—viz., 24in.

The first of the 7ft. 6in. compound class of locomotives was constructed at the Gateshead Works in 1890. The engines of this design appear capable of doing very heavy work with a low coal consumption, the average being 28lb. per mile, which, considering the heavy traffic and speed maintained, is low, being, in fact, 2lb. per mile below that of any other class of engine engaged on the same traffic.

With a train of 18 coaches, weighing 310 tons (including 87 tons, the weight of the engine and tender), a speed of 86 miles an hour was attained on a level portion of the road, the horse-power indicated being 1,068. These engines have a commodious cab, and the tenders carrying 3,900 gallons of water, thus making it possible for the run of 125 miles, from Newcastle to Edinburgh, to be performed without a stop. There is also a class of six-coupled tank engines, with a trailing radial axle. The stroke is 24in., and the diameter of cylinders h.p. 18in., and l.p. 26in. Compound engines have also been tried on the Glasgow and South Western Railway and on the London and South Western Railway.

The advantages of express locomotives being fitted with leading bogies were speedily recognised by most of the locomotive superintendents. Mr. S. W. Johnson, the Midland chief, introduced a design of such engines in 1876. The steam pressure of the early engines of this class was 140lb., but in later years this was increased to 160lb., whilst in the recent engines the pressure is still further augmented.

The same progress is to be noticed in the diameter of the cylinders of the Midland engines, the diameter having increased from 17½in. in 1876 to 19½in. at the present time. The size of the coupled wheels has also increased from 6ft. 6in. to 7ft. 9in. The length of stroke has been the same in all engines of this design—viz., 26in.

The new Midland single express engines are illustrated by Fig. 98. These locomotives have inside cylinders 19½in. diameter, with a stroke of 26in. The driving wheels are 7ft. 9in. in diameter. By standing on a railway station platform alongside one of these engines, one gets a good idea of their immense proportions, the abnormally high pitch of the boiler being especially noticeable.

Mr. Stroudley, in his “Gladstone” class of engines for the London, Brighton and South Coast Railway, adopted an entirely opposite practice. His engines had the leading and driving wheels coupled, and a pair of smaller trailing wheels. The coupled wheels are 6ft. 6in. diameter, and the trailing 4ft. 6in. diameter. The cylinders are inside, and measure 18¼1in. diameter, the stroke being 26in.

The reversing apparatus is actuated by means of compressed air, supplied by the Westinghouse brake pump; whilst part of the exhaust steam is projected against the flanges of the leading wheels, and upon condensation upon the flanges forms a lubricant to the flange surface, when pressing against the inner sides of the rails. Fig. 99 is from a photograph of “George A. Wallis,” an engine of the “Gladstone” class.

The “Tennant” (Fig. 100) class of express engines, on the North Eastern Railway, deserves mention, being the design of a general manager during the North Eastern locomotive interregnum of 1885.

The engines have four-coupled wheels, 7ft. diameter, and a leading pair of small wheels, cylinders being 18in. diameter, and 24in. stroke.

The cab is somewhat similar to the Stirling pattern on the Great Northern Railway.

The North British Railway engine, No. 592, was exhibited at the Edinburgh Exhibition of 1886, and Mr. Holmes, her designer, was awarded the gold medal.

The driving and trailing wheels are coupled, their diameter being 7ft. The fore part of the machine is supported on a four-wheeled bogie. The symmetrical appearance of this and other North British Railway locomotives is spoilt by having the safety valve located above the dome casing. The cylinders are 18in. diameter, and 26in. stroke. No. 602, another engine of this design, is notorious as being the first engine to cross the Forth Bridge, when formally opened by the Prince of Wales on March 4th, 1890, the Marchioness of Tweeddale driving the engine upon the occasion.

Mr. Holmes, in 1890, introduced another very similar design of North British Railway engines, but with coupled wheels only 6ft. 6in. diameter. These are known as the “633” class, illustrated by Fig. 101.

Turning to the Great Eastern Railway, we have to chronicle some types of locomotives designed by Mr. Holden. The express passenger engines have a pair of small leading wheels and four-coupled wheels of 7ft. diameter, with cylinders 18in. by 24in. The valves are below the cylinders, which, by the way, are both cast in one piece.