We have now reached an era in the “evolution of the steam locomotive” which, in its after development, amounted to a complete revolution in the character of the fuel used for locomotive purposes. The year 1855 found the locomotive, or rather those responsible for its working, on the threshold of successful experiments, which resulted in the complete substitution of the “black diamonds” in their natural state for locomotive fuel in preference to the use of coal after it had undergone the process of carbonification necessary to form coke.

It must not be forgotten that steam-users never had a preference for coke, but they were compelled to use it, because the more volatile coal produced so much smoke in the process of combustion that legislative action (which compels locomotive engines to be so constructed as “to consume their own smoke”) practically prevented the use of coal until science discovered a method of consuming the smoke.

There had been various attempts to reach this desirable state, and we have from time to time in this series of articles described certain of these efforts; but none of them up to the date under review had been sufficiently successful to warrant the adoption of any one of the methods proposed as a complete smoke-consumer.

The successful efforts made by Beattie, of the London and South Western Railway, to solve the problem of smoke consumption in the locomotive so as to admit of coal being used as fuel stand out prominently. The salient points of his smoke-consuming locomotive comprised an enlarged fire-box, a combustion chamber, the transverse division of the fire-box by means of an inclined water bridge, and the fire-box arched with fire-bricks. A perforated fire-door for the admission of air to the fire-box was another of the features of Beattie’s system, as were also the use of the ashpan dampers and the employment of an auxiliary steam jet in the chimney for use when the engine was at rest and the ordinary exhaust blast consequently not available. With the addition of a feed-water heating apparatus Beattie reduced the fuel consumption to .12 from .17lb. per ton mile.

The dimensions of the London and South Western Railway locomotive “Canute” (an engine filled with Beattie’s coal-burning apparatus) were:—Cylinders (outside), 15in. diameter, 21in. stroke; driving wheels, 6ft. 6in. diameter. The fire-box was 4ft. 11in. long, 3ft. 6in. wide, 5ft. 1in. deep at the back, and 4ft. 1in. in front. The combustion chamber had a flat roof, was 4ft. 2in. long, and 3ft. 6in. diameter. The tubes were 6ft. long, 1¼in. diameter, and 373 in number. Total area of fire-grate, 16 sq. ft.

The heating surface of the “Canute” was as follows:—Box, 107 sq. ft.; combustion chamber, 37 sq. ft.; tubes, 625 sq. ft.; total, 769 sq. ft. in addition to which red-hot bricks presented a surface of 80 sq. ft., not, however, for heating the water, but for the purpose of burning the smoke. Four series of trials were made with the “Canute” engine No. 135, and these are detailed in “Locomotive Engineering.” The experiments are described as “1st, the engine in its usual order, with coal, bricks, and hot feed-water; 2nd, with coal, bricks, and cold water; 3rd, with coke, bricks, and hot feed-water; 4th, with coal and hot feed-water, but without the bricks.” Three different kinds of coals were used for the experiments. The following is a brief summary of the experiments:—1st, a regular express train, of 10½ coaches, weighing 66 tons, or with the engine and tender, 99 tons. Average speed, exclusive of stoppages, 34 miles an hour; consumption of coal, 15lb. per train mile; water evaporated, 9.35lb. per lb. of coal consumed; average temperature of heated feed-water, 187 degrees. 2nd trial, a weighted train of 28 coaches, weighing with engine and tender 236 tons. Average speed, exclusive of stoppages, 30¾ miles an hour; coal consumed, 28¾lb. per mile, 8.87lb. of water evaporated by each pound of coal; temperature of feed-water, 212 degrees. 3rd experiment, with an express train, but without the fire-bricks in the fire-box, showed that a saving of 12 per cent. was due to the use of the fire-bricks, and with coke instead of coal as fuel, the saving was 24 per cent. in favour of coal; whilst the use of the feed-water heating apparatus showed a saving of 30 per cent. of fuel. Beattle’s apparatus is illustrated by Fig. 76, the “Dane,” being a similar locomotive to “Canute.”

As the feed-water heating apparatus was an important innovation in locomotive practice, it will be of interest if we append a description of the same. In outward appearance, the most noticeable portion of the apparatus was the condenser, a cylindrical appendage placed in a vertical position on the top of the smoke-box and in front of the chimney. From a casual glance, the condenser much resembled the steam-pipe of a steamship which is usually to be observed outside the smoke-stack. From the bottom of the condenser, outside the engine, a pipe conveyed the heated water and steam back to the tender. The method of working was for the exhaust steam to be discharged from the blast pipe into the condenser, which, as previously explained, was on the top of the smoke-box, and consequently right over the blast orifice. Here the exhaust steam was mixed with a jet of cold water, which was pumped into a condenser. The result of such meeting was the condensing of the steam and heating of the water, which flowed by gravitation through the pipe previously described. The supply pump for the boiler was worked off this pipe, and both the heated water and that from the tender were together pumped into the boiler. If the boiler were not being fed, the heated water from the condenser, instead of passing into the boiler, flowed through the pipe into the tender, and thus raised the temperature of the whole of the water in that vessel.

It should be mentioned that before entering the boiler the temperature of the feed-water was further increased by passing through a special heating apparatus, fixed in the smoke-box. This smoke-box chamber was heated by the exhaust steam, which passed through it after leaving the blast pipe, and before entering the external condenser placed above it. By these methods the temperature of the feed-water was raised above the boiling point before entering the boiler.

The engines of this design gave satisfaction, both as regards smoke-consuming and feed-water heating, and to Beattie, therefore, is due much of the honour of successfully overcoming the defects that previously existed in so-called “smoke-consuming” locomotives. The “Canute” can, therefore, be considered amongst the earliest of the locomotives burning coal in such a manner as to consume the smoke. It should be mentioned that in later engines built under Beattie’s patent the external condenser fixed on the top of the smoke-box in front of the funnel was not used, a modified form of interior apparatus being substituted.

It must not be supposed that at this period Beattie was alone in the field of experiment relating to “smoke-consuming” locomotives. Several other engineers were engaged in the same useful research, amongst whom we mention Yorston, Cudworth, Yarrow, D. K. Clark, Wilson, Lee and Jacques (jointly), Sinclair, and Douglas. Yorston’s plan was patented by Sharp, Stewart, and Co. in 1855. The fire-box was divided into two parts by a transverse mid-feather, which was perforated by a series of tubes, to allow the coal gases to escape and air to enter. The coal was fed into the portion of the fire-box next the tubes, the front part being reserved for coke; separate fire-doors were used for introducing the coke and coal into the fire-box. The air entering through the perforations in the fire-box, at the tube-plate end, was expected to force the smoke, etc., from the coal fire over the incandescent coke, where the combustion of the coal would be completed. The system, however, appears to have been better in theory than practice, as no particular steps were taken to push the invention in question.

With Cudworth’s system the opposite course was adopted, and resulted in his engines taking a foremost position among those burning coal as fuel.

Mr. Cudworth, the locomotive superintendent of the South Eastern Railway appears to have made his first experiments with engine No. 142, which during July, 1857, was tried as a coke-burning locomotive; but during October and November of the same year experiments were made with this engine, fitted with Cudworth’s patent grate, etc.

The principal dimensions of Cudworth’s standard passenger engines were as follows:—Cylinders, 16in. by 24in. stroke; driving wheels, 6ft. diameter; wheel base, 15ft.; heating surface, 965ft.; grate area, 21 sq. ft. Total weight in working order 30½ tons, of which the leading axle supported 9 tons 9 cwt., driving 10¾ cwt., and trailing 10 tons 6 cwt. The tender was carried on six wheels, and weighed in working order 20½ tons. These engines had inside cylinders and “back-coupled” driving wheels, and for many years comprised the principal type of South Eastern passenger locomotives. Several of them are still running, but rebuilt, their former distinguishing features—viz., the large brass dome on the centre of the boiler barrel, the raised fire-box, with a brass encased Salter safety valve, the sloping fire-grate, and the peculiar chimney—all having been removed during the present locomotive régime.

The chief feature in Cudworth’s system was the long, sloping fire-box, which was 7ft. 6in. in length, the grate being 7ft. long, illustrated by Fig. 77. The fire-box was divided into two parts by a longitudinal mid-feather, thus forming two furnaces, with separate doors; the two furnaces united at the lower end—in front of the tube-plate. The coal was introduced alternately into each furnace, being placed just within the doors; the sloping grate and the motion of the engine caused the fuel to gradually slide down the grate towards the tube-plate, and by the time the fuel had reached the lower end of the grate, the smoke had become separated from the carbon of the coal, and was consumed by the incandescent mass of fire at the lower end of the grate, as it passed over the same on its way to the tubes.

Cudworth employed neither combustion chambers nor air-bricks in his system; but air was admitted to the fire-box by means of a damper fixed in the front of the lower end of the grate. A steam-jet was fixed in the chimney to create a sufficient draught when the engine was still. Cudworth’s “smoke-consuming” locomotives were as economical in coal as Beattie’s, whilst the former’s system was much more simple.

On March 18th, 1857, Thomas Yarrow, of Arbroath, was granted a patent for his smoke-consuming apparatus for locomotives, which was used on the Scottish North Eastern Railway. The leading characteristic of the design was a flat arch of fire-bricks constructed inside an ordinary fire-box. The lower end of the arch commenced below the bottom row of tubes, and the arch was continued upwards in a slanting direction till within 8 or 10 inches of the roof of the fire-box. Upon the top of this arch were fixed a number of tubes, through which the vapours passed before reaching the ordinary boiler tubes. Hot air was supplied to the fire by means of pipes with trumpet-shaped mouths placed in front of the ashpan. The fire-bars were fixed on a transverse rocking-shaft fitted with several short arms, upon which the ends of the fire-bars rested. To prevent the formation of clinkers, an occasional rock was given to the fire-bars by the fireman, a sector being provided for the purpose. Yarrow’s system required the coal to be placed at the extreme front of the fire-box, so that the smoke was forced by the brick arch to return towards the fire-door before it could get over the arch and enter the tubes, and in the passage the denser portion of the smoke was burnt. The patent also included the use of a steam-jet in the chimney for use when the engine was not working, and the heating of the feed-water by means of the exhaust steam.

Late in 1857 D. K. Clark devised his system of smoke-consuming furnaces: the air was forced through tubes into the fire-box by the action of minute jets of steam, which acted much in the same way as the blast pipe in the smoke-box. The air-tubes were 1½in. diameter, with the steam-jet orifice contracted to one-sixteenth inch diameter.

The first locomotive fitted with D. E. Clark’s system was one of the North London Railway’s tanks. This was in January, 1858, but only one side of the fire-box was fitted; four air-tubes were employed, and with a small fire the prevention of smoke was complete. In April of the same year one of the passenger engines on the Eastern Counties Railway was fitted with Clark’s apparatus. Four air-tubes were fitted to one side of the fire-box, and three to the other side. In the following January a South Eastern Railway passenger locomotive was fitted with two rows of seven tubes each, through the front and back of the fire-box. In March, 1859, a Great North of Scotland Railway engine was fitted with tubes on Clark’s system, with such satisfactory results that the whole locomotive stock of that railway was speedily fitted with the apparatus. No complete investigation appears to have been made as to the work performed by the jets of steam as employed by Clark. It is generally supposed that the steam had a merely mechanical effect—viz., that of drawing the air into the fire-box. It has also been suggested that the steam produced a chemical combination which facilitated the combustion of the volatile gases, besides precipitating the unconsumed carbonaceous matter on the fire. The result of the adoption of the system on the Great North of Scotland Railway’s locomotives was such that the coal consumption fell to under .2lb. of coal per ton mile. A trial was also made of Clark’s system on the London, Brighton, and South Coast Railway, one of the old passenger engines being fitted with air-tubes and steam-jets to the front of the fire-box, with good results.

In 1858 Mr. Edward Wilson, who supplied the Oxford, Worcester, and Wolverhampton Railway with locomotive power by contract, fitted his system to several of the engines on that line. Mr. David Joy, the inventor of the celebrated Joy valve gear, was at that time locomotive superintendent of the Oxford, Worcester, and Wolverhampton Railway, and he possesses records of many runs of the engines so fitted, and the comparisons between the fitted and unfitted engines show an immense saving of fuel by the former; indeed, the coal consumption was remarkably low considering the severe nature of the line between Oxford and Worcester. Some short time ago Mr. Joy showed the writer the tabulated results of these trials, and, if memory serves correctly, the coal consumption averaged about 21lb. per train mile. Wilson’s system consisted in fixing several tubes from the bottom of the fire-box underneath the whole length of the boiler and smoke-box, so that the mouths of the air-tubes projected in front of the engine, and the resistance of the train when travelling forced the air through the tubes into the fire-box. By his method Wilson obtained a forced draught without the expenditure of the steam, which was necessary in Clark’s system.

Lee and Jacques’ system was introduced on the East Lancashire Railway in July, 1858. It consisted of a narrow fire-brick arch, and a deflector fixed at the top of the underhung fire-door. The deflector projected in a downward sloping direction into the fire-box. A valve for controlling the supply of air to the fire-box was fitted to the fire-door, and this valve was worked by means of a sector. The air entered the fire-box through the valve, and the deflector caused the air to be projected downwards on to the fuel, whilst the brick arch prevented the immediate escape of the gases, and kept them within the fire-box sufficiently long for the smoke to be consumed.

In December, 1858, Mr. Sinclair, the locomotive superintendent of the Eastern Counties Railway, commenced to fit some locomotives with the deflecting plate, etc., on a plan introduced by a Mr. Frodsham. The fire-door was underhung, and the baffle-plate was fixed above it, to direct the air down on to the fuel; whilst instead of a brick arch, two steam-jets were used, one on each side of the door. These also helped to force the air on to the burning fuel and to drive the liberated, but unconsumed, smoke back into the fire, when it was consumed.

Mr. Douglas’s plan was adopted by the Birkenhead Railway. He combined the use of an inclined fire-grate of large area, and a baffle-plate. In January, 1858, when first introduced, the deflector was fixed to the inner side of the fire-door, but in June of the same year an underhung fire-door and movable baffle-plate were employed. These afterwards gave place to a plain inverted scoop, to project the air right on to the fire.

After reading the description of the various plans adopted for the consumption of the smoke, readers will at once observe that each and every designer had the same object in view—viz., to supply a sufficient volume of air to the fire, and mix the air with the unconsumed gases given off by the burning coal, and then to prevent the immediate escape of this gaseous mixture from the fire-box. Being retained within the heated fire-box, the temperature of the vapour was raised sufficiently, so that the vapour readily burnt when forced by the steam deflector, or brick arch (according to the system adopted), back on to the incandescent fuel. As stated, the object of all the inventors was the same, but the methods adopted were different, and these latter (though some systems had advantages that others lacked) were successful in each case; but from the whole could be chosen some that certainly were more noteworthy, both as regards simplicity of application and design, and others that were more successful in attaining the object in view—viz., a consumption of the smoke given off by the coal. In these four years—1855-59—however, the problem of consuming the coal smoke, was successfully accomplished, and the era of the coal-burning locomotive definitely inaugurated.

Fig. 78 is an illustration of the “Nunthorpe,” No. 117 of the Stockton and Darlington Railway. This engine shows a distinct advance in locomotive construction; indeed, it is possible at the present time to see on some lines engines somewhat similar in appearance still at work. She was built by Gilkes, Wilson and Co., in 1856, and was intended for passenger traffic. Four of the six wheels were coupled, these being 5ft. in diameter. The cylinders were inside, 16in. in diameter, and with 19in. stroke. The tender was on six wheels, and the tank capacity was 1,200 gallons. The cost of the engine was £2,550. It will be observed that the weather-board of the “Nunthorpe” afforded very little protection to the driver and fireman, but its inclusion in the design of the engine was a step in the right direction.

In 1857 Beattie designed a handy class of passenger tank engines for the L. and S.W.R. Three were built at first, and named “Nelson,” “Howe,” and “Hood.” They had four coupled wheels, 5ft. diameter, and a small pair of leading wheels. The cylinders, which were outside, were 15in. diameter, the stroke being 20in. These engines are illustrated by Fig. 79. They were good locomotives, and “Hood” and “Howe” continued in work till 1885.

Fairlie is usually given the credit of introducing double locomotives with a centre foot-plate. By reference to Chapter IX., it will be seen that the design was patented by Pearson, of the Bristol and Exeter Railway, as long ago as 1847, and in 1855 a double engine, built by R. Stephenson and Co., was at work on the Giovi incline of the Turin and Genoa Railway. The incline in question commences 7¾ miles after leaving Genoa, and is six miles long, the average gradient being 1 in 36. The double locomotive was of the tank type. The wheels were 3ft. 6in. diameter, the cylinders 14in. diameter, and the stroke 22in. The machine actually appears to have been two engines placed fire-box to fire-box, and connected by means of a foot-plate between the two fire-boxes. The combination, with fuel and water, weighed 50 tons. In fine weather a load of 100 tons was hauled up the Giovi bank at 15 miles an hour; in bad weather the load was reduced to 70 tons.

The first portion of the East Kent Railway from Chatham to Faversham was opened in January, 1858, the original locomotives being designed by Crampton, who was one of the contractors for the construction of the line. The engines in question were “tanks,” and weighed 32 tons each—at that period considered an excessive weight for an engine. They were also unsteady and generally unsatisfactory, frequently running off the metals.

Mr. Robert Sinclair was appointed locomotive superintendent of the Eastern Counties Railway in 1858, and his first design of engines was a class for working the goods traffic, of which only six were constructed, Rothwell and Co. being the builders. The engines had a pair of leading wheels, 3ft. 7in. diameter, and two pairs of coupled wheels, 5ft. diameter; the cylinders were 18in. diameter, the stroke being 22in.

During the following years another class of goods engines (Fig. 80) were built by various firms from Mr. Sinclair’s improved design. Indeed, as will be seen later on, some were even constructed by the French firm of Schneider and Co. These had outside cylinders, and inside frames to all wheels. The coupled wheels (D. and T.) were 6ft. 3in. diameter, and the leading 3ft. 9in. diameter. The boiler was 10ft. 9in. long by 4ft. 2in. diameter, and contained 203 tubes, of 1¾in. diameter; heating space, 1,122 sq. ft.; weight, 35½ tons. Twenty-one of these engines, built by Neilson and Co., had Beattie’s patent fire-box, which was surmounted by a large dome. These were numbered 307 to 327. When Mr. W. Adams was appointed locomotive superintendent of the Great Eastern Railway, he rebuilt several of these engines with a leading bogie in place of the pair of wheels.

In November, 1858, a design of locomotive engine was patented, four pairs of coupled wheels being employed, all of which were located under the boiler barrel. The two leading pairs of wheels had outside axle-boxes, and the two trailing pairs inside axle-boxes, the latter having a lateral motion. The cylinders were inside, under the smoke-box, but the method proposed for working the locomotive was of a curious type, being somewhat after the fashion employed in ancient steamboats, the pistons working out towards the front buffer beams, but connected to the leading wheels by outside cranks working off the cross-heads.

A design for four-wheel tank engines was patented by S. D. Davison, in February, 1859, the leading feature being plate-iron frames formed into tanks for holding a supply of water.

Attention must now be given to an invention that has proved of enormous value to the locomotive engineer, but which from its simplicity of action, yet apparent impossibility, was not at first deemed worthy of practical use. On July 23rd, 1858, a patent was granted to H. J. Giffard, a Frenchman, for his injector, or boiler feeder, which in a short period almost completely superseded feed pumps, with their attendant friction, uncertainty of action, and excessive outlay for maintenance and repair. But above these minor disadvantages of the feed pumps, the injector removed from the minds of locomotive engineers that great source of danger, a short supply of water in the boilers, as well as the additional expense and inconvenience of “exercising” the locomotives solely for the purpose of filling the boiler, or, where such a method was inconvenient, of working the engine over a “race” for the same purpose. The theory of the injector did not originate with Giffard, for as long ago as 1806 Nicholson mentioned it as applicable for forcing water, whilst other philosophers have suggested its utility; indeed, the principle was used in connection with vacuum sugar boiling pans 20 years before Giffard’s patent. The story of Giffard’s accidental discovery of the action of steam and water in supplying a steam boiler with additional water reads almost like an extravagant romance, but many other great inventions and scientific discoveries had beginnings that appeared quite as improbable. The action of the injector, although curious, is well known, and therefore needs no description here. It is stated that Ramsbottom’s “Problem,” built at Crewe in November, 1859, was the first locomotive fitted with Giffard’s “injector.” This engine was the prototype of the world-famous “Lady of the Lake” class. Her dimensions were, outside cylinders, 16in. by 24in.; single driving wheels, 7ft. 7½in. diameter; weight in working order, 27 tons. These engines have inside frames and bearings to all the six wheels.

An invention of Mr. Ramsbottom in connection with the improvement of the working of the locomotive deserves attention at this point. We refer to his self-filling tender apparatus, as introduced in 1860 on the London and North Western Railway system, and afterwards partially on the Lancashire and Yorkshire Railway, but which until the last year or so has not been used on other lines. The speed competition of recent years, and the expiration of the patent, has now caused the Great Western, Great Eastern, and North Eastern to adopt the water pick-up apparatus. One advantage of the system is, of course, the considerable reduction in the dead weight—a not unimportant factor in express train running. The superiority of Ramsbottom’s system is easily seen by comparing the small light tenders in use on the London and North Western Railway with the gigantic ones adopted by the Great Northern, Midland, and other lines running long distances without stopping, but which systems are unsupplied with the water trough and the necessary pick-up apparatus. The first pair of water troughs appear to have been put down near Conway, on the North Wales section of the London and North Western Railway. They were of cast-iron, 441 yards long, 18in. wide, and 7in. deep, the water being 5in. deep. At each end of the main trough was an additional length of 16 yards, rising 1 in 100. It was towards the end of 1860 that the first trial of the trough system was made. Here, again, as in the case of the “injector,” the arrangement requisite to produce the effect is so simple that at first blush the effect appears to be the result of some marvellous secret power rather than the operation of a simple natural law, the effect of the travelling scoop upon the water being exactly the same as if the water were forced against a stationary scoop at a velocity equal to that at which the train is travelling. The lowest speed at which the apparatus works properly is something about 22 miles an hour. This speed, however, brings it within the scope of fast goods trains, whilst express trains can scoop up the water when travelling at 50 miles an hour, and can pick up about 1,500 gallons in the length of the trough—quarter of a mile. The speed of the train would not appear to have much effect upon the water picked up in passing over a trough, as although with a slower train less water would be raised per second, yet the extra length of time spent in travelling over the trough would compensate for the smaller amount of water raised per second. The water supply-pipe is fixed inside the tender; it is slightly curved throughout its entire length, and is expanded towards its upper end to about ten times the area of the bottom, in order to reduce the speed or force of the incoming stream, which is directed downwards by the bent end or delivering mouth at the top of the pipe. To the lower end of this pipe is fitted a movable dip-pipe, which is curved forward in the direction of the motion of the tender, so as to act as a species of scoop. This dip-pipe is rendered movable and adjustable in various ways, with a view to its being drawn up clear of any impediments, such as ballast heaps lying on the way, and also to regulate the depth of immersion in the water of the feed-water trough, the dip-pipe being capable of sliding up inside the feed-pipe by a convenient arrangement of rods and levers.

In order that the dip-pipe may enter and leave the feed-trough freely at each end, the rail surface at that part of the line is lowered a few inches, a descending gradient at one end of the trough serving to allow the dip-pipe to descend gradually into the trough, whilst a rising gradient at the opposite end enables it to rise out of the trough again, the intervening length of line between the two gradients being level. To meet emergencies, Mr. Ramsbottom provided a small ice-plough, to be used occasionally during severe frost for the purpose of breaking up and removing any ice which might form in the trough. This plough consisted of a small carriage mounted on four wheels, and provided with an angular-inclined perforated top, which worked its way under the ice on being pushed along the bottom of the trough, and effectually broke it up and discharged it over each side.

A very powerful class of broad-gauge saddle tank locomotives was designed by Brunel for working the heavy coal traffic over the severe gradients of the Vale of Neath Railway. These engines were supported by six-coupled wheels of 4ft. 9in. diameter, the cylinders being 18in. diameter, and the stroke 24in. The heating surface was 1,417.6 sq. ft.; the water capacity of tanks was 1,500 gallons. The engines, which were fitted with Dubs’ wedge motion, were built by the Vulcan Foundry Company, and weighed 50 tons in working order. A noteworthy performance of one of these locomotives consisted in hauling a train of 25 loaded broad-gauge trucks, each weighing 15 tons, the gross weight, including the engine, amounting to 425 tons. This train travelled up a bank of 1 in 90 for a distance of 4½ miles. Such a load on the gradient mentioned is equal to one of 1,275 tons on the level, and in a general way we do not find engines hauling trains of the latter weight upon our most level lines. The Vale of Neath performance must, therefore, be regarded as an exceptional locomotive feat. These engines were numbered 13, 14, and 15, and not being provided with compensating beams between the wheels, it is stated that one axle frequently carried 20 tons of the total weight. During 1860 these three locomotives were, under the advice of Mr. Harrison, rebuilt as tender engines, to reduce the weight on the wheels, the excessive amount of which had been very destructive to the permanent-way. The cost of the alterations to the engines and the addition of the tenders was £700 each engine. About the same time some of the other Vale of Neath six-wheels-coupled engines were converted into four-wheels-coupled bogie locomotives.

The locomotive now to be described had but a very shadowy existence; it was rather a tentative essay to produce a steam locomotive without the aid of a fire. The idea when proposed by Sir John Fowler was not new, for more or less successful essays had already been made on a small scale, with engines, the steam for propelling which was generated in the same manner as in Fowler’s locomotive.

In 1853 a railway was incorporated as the North Metropolitan; the next year a new Act was obtained, and the title changed to the Metropolitan. This authorised the construction of a railway from the Great Western Railway at Paddington to the General Post Office; powers were afterwards obtained to allow the City terminus to be in Farringdon Street instead of at the Post Office. The Great Western Railway subscribed £175,000 of the capital, and for the convenience of that Company’s through traffic the Metropolitan was laid out on the mixed-gauge, and when it was first opened it was worked on the broad-gauge only, by the Great Western Railway—a most sensible arrangement, and one which ought never to have been relinquished, seeing how well adapted the wider vehicles were for conveying the immense crowds that travel by every train on this line.

The Act of Incorporation specially provided that the line was to be worked without annoyance from steam or fire. At first it was proposed to convert the water into steam by means of red-hot bricks placed around the boiler, and Mr. (afterwards Sir) John Fowler designed such a locomotive, which was built by a Newcastle firm, and tried on the Metropolitan Railway between Bishop’s Road and Edgware Road Stations before the line was opened. The first trial took place on Thursday, November 28th, 1861. The following is an account of the trip:—“The engine was of considerable size, and it was stated that it could run on the railway from the Great Western at Paddington to Finsbury Pavement without allowing the escape of steam from the engine or smoke from the fire. A few open trucks were provided with seats, and when the gentlemen were seated, the new engine propelled them under the covered way of the Metropolitan Railway to the first station at the eastern side of the Edgware Road, and back again to the Great Western Station, the steam and smoke being shut off. The tunnel, or covered way, was perfectly fresh and free from vapour or smoke. On the signal being given to work the engine in the ordinary way, a cloud of smoke, dust, and steam soon covered the train, and continued until it emerged from the tunnel into the open air. The experiment was perfectly successful, but it was understood that engines so constructed would be rather more expensive to work than those running in the ordinary way.” To work the Metropolitan Railway on this system would have required the erection of immense boilers at both ends of the line to heat the water for the locomotive, and also furnaces for making the bricks red-hot, whilst the charging of the locomotive boilers with hot water and the fire-boxes with hot bricks would have occupied some considerable time at the end of each trip.

It is, of course, well known that the experiment was very far from being “perfectly successful.” Indeed, “failure” would be a much better definition of the hot-brick engine, since the proposed method of working was not carried out. We understand the engine was sold to Mr. Isaac Watt Boulton, the well-known purchaser of second-hand locomotives, and for some time remained in his “railway museum” before being finally scrapped. The Metropolitan Railway had, consequently, upon the failure of the hot-brick engine, to fall back upon the Great Western Railway for working the underground line, until Sir John Fowler’s later design of engines, constructed by Beyer, Peacock, and Co., were ready to work the traffic.

In 1862 Fletcher, Jennings, and Co., of Whitehaven, designed a handy type of saddle tank engine for shunting purposes, etc. The engine ran on four wheels, 3ft. 4in. diameter, the wheel base being 6ft. The cylinders were 10in. diameter, with 20in. stroke. Allan’s straight link motion was employed, and was worked off the leading axle (it will be understood that the four wheels were coupled). This method of actuating the valves was not conducive to good working, as, of course, if the coupling-rods worked slack the valve gear motion became disorganised.

Fig. 81 is a photograph of engine No. 75, of the Taff Vale Railway, built at the Company’s Cardiff Works in 1860. The six-coupled wheels were 4ft. 8in. diameter, the cylinders were 16in. diameter, and the stroke was 24in. No. 75 weighed 32 tons in working order; the steam pressure was 130 lbs. per sq. in. She was employed in the heavy mineral traffic of the Taff Vale Railway, and from her design well calculated to work over the heavy gradient of that system.

In 1862 the L. and S.W. Railway purchased some second-hand engines from a contractor. They were built by Manning, Wardle, and Co., Leeds, and comprised six-wheels-coupled saddle tank engines. The wheels were 3ft. diameter; cylinders, 12in. by 18in. stroke; wheel base, 10ft. 3in.; length over buffers, 21ft. 6in.; weight, empty, 14 tons 8 cwt., loaded, 16 tons 4 cwt. The fire-box was surmounted by a safety valve enclosed within a high fluted pillar. The steam pressure was 120lb. One of these engines is leased to the Lee-on-the-Solent (Light) Railway, and may be seen working the traffic on this little line, which, by the way, spends over twopence to earn each penny of its gross income.

Before leaving the London and South Western Railway and its goods locomotives, it is as well to record the dimensions of the “Meteor,” No. 57, constructed at Nine Elms in 1863 from the designs of Mr. Beattie. The cylinders were 16½in. diameter, 22in. stroke; the leading wheels were 3ft. 3in., and the coupled (D. and T.) wheels 5ft. diameter; the wheel base was 14ft., of which 8ft. 2½in. was between the coupled wheels. The leading wheels were under the boiler, and the front buffer beam was about 6ft. in advance of the centre of this axle. An immense dome was fixed on the raised fire-box; the safety valve was within an inverted urn-shaped case on the boiler barrel. The weather-board had slight side-wings, and was curved upwards at the top, and so formed an incipient cab. The fire-box sloped from the tube-plate towards the foot-plate. The total weight, in working order, was 32 tons 18 cwt., of which 11 tons 9 cwt. was on the leading, 11½ tons on the driving, and 9 tons 18 cwt. on the trailing axle. The tender was supported on six wheels, 3ft. 9¾in. diameter, and had a tank capacity of 1,950 gallons.

By a marvellous addition of a big head and a bigger tail (to say nothing of various legs), the diminutive body of the East Kent Railway had, in August, 1859, blossomed into the London, Chatham and Dover Railway; and for this railway 24 locomotives were supplied by various firms from Crampton’s designs. They were numbered 3 to 26. The design was peculiar—a leading bogie having wheels 3ft. 6in. diameter, and a base of 4ft., and four-coupled wheels 5ft. 6in. diameter. The cylinders were outside, and had a stroke of 22in., the diameter being 16in. As in the “London” and other Crampton engines, the cylinders were placed about midway between the smoke and fire-boxes, whilst the connecting-rods actuated the rear pair of coupled wheels, so that in describing the position of the wheels of these engines we should have to enumerate them as “leading bogie,” “centre,” and “ driving.” A compensation lever connected the centre and driving wheels. Gooch’s valve gear was used. Like other engines of Crampton’s design, this class was a failure, and within three or four years they were rebuilt as six-wheel engines, with inside cylinders and outside frames; some of them, as reconstructed without a bogie, are still in active service on the London, Chatham and Dover Railway.

Before the grave faults inherent in the previously described class of engines had been, fully appreciated, the London, Chatham, and Dover Railway had arranged for a second batch of engines from another of Crampton’s designs. These consisted of five engines constructed by R. Stephenson and Co. in 1862. The locomotives in question were worked on the principle patented by W. Bridges Adams, and previously described in an earlier chapter—viz., an intermediate driving shaft, coupled by outside rods to the driving wheels, situated behind the fire-box. The cylinders were 16in. diameter by 22in. stroke, and within the frames. The driving wheels were 6ft. 6½in. diameter, and bogie wheels 4ft. 0½in. diameter. Cudworth’s sloping fire-box, fitted with a longitudinal mid-feather, was employed. The heating surface amounted to 1,200 sq. ft., made up of 130 sq. ft. fire-box and 1,070 sq. ft. tubes, which were 2in. diameter, 10ft. 10in. long, and 189 in number. The grate area was 26 sq. ft.

The engines in question were named, etc., as follows:—

As remarked in describing the previous class, Crampton’s engines were in this case also found to be unsuitable, so that the London, Chatham and Dover Railway rebuilt the five engines, when the intermediate driving shaft was provided with a pair of wheels, and the engines became “four-coupled bogies.” The diameter of the cylinders was increased to 17in.; the Cudworth fire-box was dispensed with, and the heating surface reduced, the present dimensions being—fire-box, 100 sq. ft.; tubes, 987 sq. ft.; grate area, 16¼ sq. ft.; weight in working order: on bogie, 14 tons 12 cwt.; driving wheels, 14 tons 12 cwt.; and on trailing wheels, 10 tons; total, 38 tons 16 cwt.