The evolution of the steam locomotive (1803 to 1898)

During 1845 R. Stephenson and Co. built seven of their “long boiler” engines, with outside cylinders, for working the goods traffic of the Eastern Counties Railway. Fig. 35 is an illustration of one of these ungainly specimens of locomotive construction. The boiler barrel was no less than 13ft. 6in. in length, all the axles were beneath the barrel, the leading wheels were 3ft. diameter, and the driving and trailing (coupled) wheels 5ft. 9½in. diameter. The cylinders were 16in. diameter, the stroke being 21in. In working order, these locomotives weighed 23 tons 12 cwt. After looking at the illustration, it is scarcely necessary to add that these engines were very unsteady when travelling, the oscillation being excessive.

In the arrangement of inside and outside bearings to the various wheels of the patent engines, designed by John Gray for the Hull and Selby Railway (previously described), we make acquaintance with the embryo design, afterwards perfected, and known the whole world over as the “Jenny Lind” class.

In 1846 Gray had become locomotive superintendent of the Brighton Railway, and he prepared another design of express engines for that line, in which the type now known as “Jenny Lind” was further developed. J. Hackworth and Co. obtained the contract for the supply of twelve of these locomotives, and in November, 1846, they delivered the first pair, numbered 53 and 54. Fig. 36 represents No. 49, one of these engines. The leading and trailing wheels were 3ft. 6in. diameter, the drivers being 6ft. diameter. Cylinders 15in. by 24in. stroke. Heating surface: tubes, 700 sq. ft.; fire-box, 79 sq. ft. Inside bearings were provided to the driving, and outside to the leading and trailing wheels; the engines were fitted with Gray’s “horse-leg motion,” and several of the dozen had two square-seated steam domes, one located on the centre of the boiler barrel, the other over the fire-box. Each dome was provided with a steam safety valve. The steam pressure was 100lb. per square inch.

These engines were found to be good at hauling heavy loads (as computed 50 years ago) at speeds up to and slightly exceeding 40 miles an hour.

In 1846 Stephenson and Howe obtained a patent for a three-cylindered engine. Z. Colburn, in his “Locomotive Engineering,” exposes the fallacy of the idea that the action of the steam admitted alternately to cylinders whose centres are far apart, sets up a dangerous sinuous motion. The object of Stephenson and Howe’s three-cylinder engine was to overcome this winding motion. Colburn states that a “few pounds of counterweight would have served a better purpose than the extra cylinder and working parts.” Two engines appear to have been built on this plan before the true cause of the rocking motion and the real way of overcoming it, were fully grasped by the patentees. The outside cylinders were only 10½in. diameter and 22in. stroke; whilst the centre or inside cylinder was 16⅜in. diameter, but the stroke in this case was restricted to 18in. It is needless to add that these three-cylinder locomotives were not successful.

Passing reference must be made to the celebrated gauge experiments which took place during the last days of December, 1845, and resulted so greatly in favour of the broad-gauge, despite the fact that the Great Western Railway had no new engines prepared for the competition, but used those regularly in work on the broad-gauge railways.

The narrow-gauge experiments were made on the Great North of England Railway, a special engine being built for the purpose by R. Stephenson and Co., and called “A.” The “A” was a six-wheel long boiler engine, with outside cylinders and 6ft. 6in. driving wheels. Hot water for supplying the boiler was used on the narrow-gauge in place of cold on the broad-gauge. The latter started from a state of rest, but the narrow-gauge approached the starting-point at as great a velocity as possible; yet, notwithstanding these sharp practices of the narrow-gauge officials, they were completely beaten in the experiments.

The Swindon Works commenced to build locomotives early in 1846; and, as its name implies, the “Premier” was the first engine constructed at these now world-famous locomotive shops.

She was a six-coupled goods engine, with wheels 5ft. diameter.

Numerous engines of this type, with slight modifications, were built at Swindon; “Hero” (Fig. 37) is a good example of the G.W. standard goods engine at the time.

The narrow-gauge engineers having made frantic efforts to produce locomotives as powerful as those in use on the Great Western Railway, the directors of the latter company decided to have a larger and more powerful engine constructed, and Mr. Gooch received orders to construct a colossal locomotive, and to have it in work before the commencement of the Parliamentary Session of 1846. From the time the decision was arrived at, until the “Great Western” was at work, only 13 weeks elapsed, during which short period the design of the engine had to be decided upon, the drawings made, the patterns prepared, and the whole of the complex machinery made and put together; yet those three months were sufficient to produce this most famous locomotive.

As originally constructed, the “Great Western” (Fig. 38) was a six-wheel engine, the dimensions being:—Cylinders, 18in. diameter and 24in. stroke; driving wheels, 8ft. diameter; leading and trailing wheels, 4ft. 6in. diameter; 278 tubes, 9ft. long, 2in. diameter; fire-box (outside), 5ft. 6in. by 6ft., inside 4ft. 1Oin. by 5ft. 4in., with partition through the centre; heating surface, tubes 1,591 sq. ft.; fire-box, 160 sq. ft.; grate area, 20ft.; height, from level of rail to top of boiler, 9ft. 6in.; the chimney was 5ft. 2in. high; length of engine, 24ft.; weight (empty), 36 tons. In this engine Gooch retained the Gothic fire-box, as supplied to the engines he had previously designed. By the way, a picture, purporting to be an illustration of this engine, was given in a book on locomotive history, with the flush top fire-box and four leading wheels! The “Great Western” continued to work trains on the Great Western Railway until the end of 1870, having run a total distance of 370,687 miles during the 23¾ years she was in work.

On Saturday, June 13th, 1846, the “mammoth” locomotive (as the “Great Western” was usually called) made a sensational trip from London to Bristol and back, and, but for the failure of one of the six-feed pumps, necessitating slower running, even better results would have been attained. But, despite the accident, the result of the trip came like a “bolt from the blue” upon the narrow-gauge engineers.

The train weighed 100 tons, and consisted of ten first-class carriages, seven of which were ballasted with iron, the other three being occupied by the directors and those interested in the experiment. The train started from Paddington at 11 hours 47 minutes 52 seconds; at Didcot a stop of 5¼ minutes was made; Swindon was reached in 78 minutes. After staying there 4 minutes 27 seconds, the journey was continued to Bristol, the whole distance of 118½ miles being covered in 2 hours 12 minutes, or at the rate of 54 miles an hour, or, excluding the 9¾ minutes spent in the two stoppages, at about 59 miles an hour for the complete journey, including the slowing down and getting up speed again on three occasions. The maximum speed was obtained between the 82nd and 92nd mile-posts (from the 80th to the 85th mile there is a falling gradient of 8ft. per mile, and from the 85½th to about the 86½th mile there is a falling gradient of about 1 in 100, and a fall of 8ft. per mile then reaches to about the 90½th mile-post; a rising gradient of 8ft. per mile then succeeds and extends beyond the 92nd mile-post), performing the ten miles in 9 minutes and 8 seconds, or at an average speed of nearly 66 miles an hour. The 87th and 88th miles, on a falling gradient of 8ft. per mile, were run over at a rate of 69 miles per hour.

One Monday early in June, 1846, the “Great Western” was attached to the 9.45 a.m. express Paddington to Exeter, the crack train of that time, which, indeed, continued to be the fastest ordinary passenger train until the establishment of the “Flying Dutchman” many years later. When it was advertised that this train would perform the journey between London and Exeter in 4½ hours, people said it was impossible; what, then, must have been thought of the run performed by the “Great Western” and chronicled below? The 193¾ miles from Paddington to Exeter were covered in 214 minutes (3 hours 34 minutes) running time, being an average rate of 55¼ miles per hour. The actual running time on the journey was as follows:—

The return journey was performed in less time, and could have been accomplished with ease at a rate exceeding 60 miles an hour The actual running time, exclusive of stoppages, was as follows:—

After the engine had been running a short time, Gooch found the weight on the leading axle too much to be safely carried by one axle, and he fitted another pair of leading wheels to the “Great Western” (Fig. 39), making her an eight-wheeled engine, having a group of four wheels in front of the driving wheels. It must be remembered that these four wheels were not affixed to a bogie frame. So well satisfied were the directors of the Great Western Railway with the “Great Western” that 29 more engines of almost similar design (except the domed fire-box) were constructed during the next eight years, and these engines, with a few of the same design, built at a more recent period, worked the famous broad-gauge expresses between London and Newton Abbot until the abolition of the broad-gauge in May, 1892.

In March, 1847, the Great Western Railway laid down a length of line at Maidenhead for the purpose of testing Elijah Galloway’s system of locomotive propulsion with horizontal driving wheels. The horizontal wheels gripped a centre rail, and the engine not being dependent upon the weight placed upon the driving wheels for adhesion, was enabled to ascend inclines that were impossible for ordinary locomotives; whilst the fact that the two horizontal driving wheels were pressing one on either side of the centre rail enabled the engine to safely pass round curves of extremely short radii, such as would be impossible with ordinary locomotives. The line put down at Maidenhead was on an incline of 1 in 19, but a model engine and train successfully ascended an incline of 1 in 6. Mr. D. Gooch gave the following account of the experiments:—

The “Atlas,” constructed for the Manchester and Sheffield Railway, deserves notice. She was built by Sharp Bros. and Co., from the designs of Mr. Beyer, their then chief engineer, but afterwards head of the well-known firm of locomotive builders, Beyer, Peacock and Co., of Manchester.

The “Atlas” commenced work in May, 1846, and during the succeeding 17 months she travelled 40,222 miles, with a coke consumption of 36.53lb. per mile, although engaged in hauling heavy goods trains. The engine had inside cylinders, 18in. diameter, 24in. stroke; the whole of the framing and bearings were inside the wheels; the boiler was 13ft. 6in. long and 3ft. 6in. diameter, and contained 175 brass tubes of 1⅝ in. external diameter; the wheels were cast-iron, 4ft. 6in. diameter; a copper fire-box was provided, its inside measurements being 3ft. 8in. long, 3ft. 3½in. wide, and 3ft. 4½in. from the fire-bars to the top. The water space around the fire-box was 3in., and a mid-feather, 4in. wide, divided the fire-box.

The cylinders were secured to each other by internal flanges, which formed the bottom of the smoke-box, and also the chief cross-stay between the frames. The valves were in one chest, located below the cylinders, and inclined towards each other. The weight of the valves was carried by spindles working through stuffing-boxes. The regulator was provided with two perforated discs, so that the steam was admitted very gradually, the volume increasing as the two sets of perforations came opposite each other.

The weight of the “Atlas” was 24 tons, and five other engines of exactly similar designs were supplied to the Manchester and Sheffield Railway.

Another engine of the same description was supplied to the Manchester and Birmingham Railway, and on October 3rd, 1836, “No. 30” hauled a train of 101 wagons, weighing 597 tons, from Longsight to Crewe, a distance of 29 miles, at the average speed of 13.7 miles an hour.

The mention of a powerful engine and a record train on one railway naturally suggests a better one on another line, so we have the “Essex” going “one better” than “No. 30.”

This time we have a load of 149 loaded wagons (probably equal to 890 tons), and forming a train nearly half a mile long. The “Essex” is also stated to have hauled a train of 192 empty trucks. The engine in question was built for the Eastern Union Railway by Stothart, Slaughter, and Co., Bristol, in 1847, and had wheels 4ft. 9in. diameter, cylinders 15in. by 24in. stroke, weight 22 tons.

In 1846, Stephenson and Co. supplied the South Eastern Railway with an engine called the “White Horse of Kent” (the “White Elephant of Newcastle” would have been a far more descriptive name). This engine probably exhibited the “long boiler” folly in a more marked manner than any other engine of that notorious class. She was 21ft. 10in. long, with a wheel base of only 10ft. 3¼in.! She had cylinders 15in. by 22in. stroke, 5ft. 6in. driving wheels, and weighed 18¾ tons. Gooch says this engine was so unsteady that it was necessary to be tied on to make experiments on the smoke-box temperature, and that the tubes were so long that one end of the engine was actually condensing the steam generated at the other end!

At this time Mr. T. R. Crampton turned his attention to locomotive construction, and patented a design of locomotive. He claimed for his design the following advantages—viz., a reduction of the rocking and vibrating motion, obtained by lowering the centre of gravity, and by locating the greater portion of the weight between the supports; an increased heating surface; and a superiority of arrangement of the working parts, the whole of which were placed immediately under the eye of the driver.

The first engine constructed on this principle was the “Namur” (Fig. 40), built under Crampton’s patent by Tulk and Ley, of the Lowcra Works, Whitehaven, for the Namur and Liège Railway.

The illustration shows that the chief peculiarity of the “Namur” was the position of the driving wheels, the axle of which was behind the fire-box, so that the axle extended across the foot-plate. One spring, formed of plates, also extended across the back of the fire-box, parallel with and above the driving axle, and acting upon it at the bearings.

The chimney was 6ft. 6in. high; the smoke-box was very narrow, being no wider than the diameter of the chimney; all the wheels had inside bearings; the cylinders were outside, and horizontal; the valve chests were on the outer side of the cylinders, so that the eccentrics were at the extreme ends of the axles, beyond the wheels, and quite exposed.

The boiler barrel was surmounted by an immense fluted dome, which was fitted with two lever safety valves, whilst a third one, of the spring pattern, was provided on the fire-box casing.

The following are the principal dimensions of the “Namur”:—

Diameter of driving wheels, 7ft.; diameter of leading and middle wheels, 3ft. 9in.; total wheel base, 13ft.; cylinders, 16in. diameter, 20in. stroke; number of tubes, 182—length 11ft., external diameter 2in.; fire-box, 4ft. 3in. long, 3ft. 5in. wide; area of fire-tube, 14ft. 6in.; heating surface: fire-box 62ft., tubes 927ft., total 989ft.

The engine was completed early in February, 1847, and previous to its exportation, it was tried for several weeks on the London and North Western Railway, running over 2,300 miles. All classes of traffic were hauled by the engine, and she gave general satisfaction. A speed of 75 miles an hour was attained between Willesden and Harrow, when running “light.” On another occasion, 50 miles an hour was attained on a trip from Camden Town to Wolverton with a coke train, weighing 50 tons, between Tring and Wolverton.

The “Namur” weighed 22 tons, of which 7½ tons were on the leading wheels, 4 tons on the centre wheels, and 10½ tons on the driving wheels.

The L. and N.W.R. were so satisfied with the “Namur” that Tulk and Ley were instructed to build a Crampton engine for that railway; and the “London” (Fig. 41) was produced in 1848 in response to this order. She was the first engine on the southern division of the L. and N.W.R. to have a name. The driving wheels were 8ft. diameter, the cylinders 18in. diameter and 20in. stroke. The boiler was oval in shape, its vertical diameter being 4ft. 8in., and its horizontal diameter 3ft. 10in. The heating surface was 1,350 sq. ft. The fire-box extended below the driving axle.

In April, 1847, Mr. D. Gooch’s famous broad-gauge express engine, “Iron Duke,” commenced to run. Fig. 42 represents an engine of this class. She was the first of a set of twenty-nine locomotives of almost similar construction, designed to work the Great Western express trains. The “Iron Duke” was an improvement on the celebrated “Great Western,” previously described; the most noticeable difference was the absence of the domed fire-box in the “Iron Duke.” The total mileage of this engine, up to October, 1871, when it was withdrawn from service, amounted to 607,412 miles. The best-known engine of the class is “Lord of the Isles,” built at Swindon in 1850, and exhibited at the International Exhibition, London, 1851; she commenced to run July, 1852, and continued in active service on the Great Western Railway for 29 years, during which time 789,300 miles were covered by the “Lord of the Isles.” This famous broad-gauge locomotive is still preserved by the Great Western Railway.

The next point in the evolution of the locomotive that deserves attention is the famous class of engines known as the “Jenny Lind” design.

Much has been written concerning these engines during recent years, and many uncorroborated and absurd statements have been made; but it was most clearly demonstrated that to Mr. David Joy was due the chief honour of designing the successful class of locomotive known far and near as “Jenny Linds.” Such a design was elaborated from the adoption of the best features of the several descriptions of locomotives then in use.

The first of the type of engine afterwards known as the “Jenny Lind” class was constructed for the London and Brighton Railway by E. B. Wilson and Co., Railway Foundry, Leeds, and was commenced building in November, 1846, and completed in May, 1847. The principal features of the engines may be summarised as follows:—Steam pressure 120lb. per square inch, inside bearings to driving and outside bearings to the leading and trailing wheels, outside frames, outside pumps located between the driving and trailing wheels, and worked by cranks fixed on the outside of the driving axles. The engine had a raised fire-box; the dome was fluted and had a square seating; the safety valve was enclosed within a fluted column, and fixed on the fire-box.

Polished mahogany lagging was used for both the boiler and fire-box, the same being secured by bright brass hoops. The tops of the safety valves and dome were bright copper. The first trip of the “Jenny Lind” was from Leeds to Wakefield and back. Ten engines of this class were supplied to the London and Brighton Railway, and were numbered 61 (Fig. 43) to 70. The principal dimensions were:—Driving wheels 6ft. diameter; leading and trailing wheels, 4ft. diameter; cylinders (inside), 15in. diameter, 20in. stroke; boiler, 11ft. long, 3ft. 8in. diameter; 124 tubes, 2in. diameter. A water space of 3in. was left between the inner and outer shells of the fire-box. Heating surface, tubes 700 sq. ft., fire-box 80 sq. ft.

It is significant to note that in the original description of the “Jenny Lind,” published in 1848, we are informed that “in establishing this class of engine Messrs. Wilson have studied less the introduction of dangerous novelties than the judicious combination of isolated examples of well-tried conveniences.” This statement exactly agrees with those recently made by Mr. Joy.

The great success of the “Jenny Lind” type caused Sharp Bros. and Co. to introduce a rival class of engines nicknamed “Jenny Sharps.”

The engines were provided with a mid-feather in the fire-box for the purpose of augmenting the heating surface. The principal dimensions of the “Jenny Sharps” were as follow:—Steam pressure, 80lb.; cylinders, 16in. diameter, 20in. stroke; driving wheels, 5ft. 6in. diameter; heating surface, tubes (of which there were 161, each 10ft. long and 2in. diameter) 847 sq. ft., fire-box, 72 sq. ft.; total, 919 sq. ft. Mr. Kirtley, the locomotive superintendent of the Midland Railway, arranged a trial between the rival “Jennies,” and the event came off on May 4th, 5th, and 6th, 1848.

Sharp’s engines were Nos. 60 and 61, and Wilson’s Nos. 26 and 27. The first trip was with a load of 64 tons, made up of nine carriages and two brake-vans, weighted with iron chairs to 64 tons.

Sharp’s No. 60 took the first train, the weight being, engine 21 tons 9 cwt., tender 12 tons 11 cwt., load 64 tons; total, 98 tons, or, including officials, etc., about 100 tons.

The journey was from Derby to Masborough, 40¼ miles, the line rising for the first 20 miles at about 1 in 330, and falling for the remainder of the distance at about the same rate. The weather was fine, the metals dry, and there was no wind.

William Huskinson drove the train, which left Darby at 3h. 39min. 5½ sec. p.m., and arrived at Masborough at 4.28 p.m. Among the passengers were Messrs. Kirtley, locomotive superintendent; Marlow, assistant locomotive superintendent; Harland, carriage superintendent; E. B. Wilson and Fenton, of the firm of E. B. Wilson and Co.; and T. R. Crampton.

The first 18 miles up the bank of 1 in 330 were covered in 25 minutes 12½ seconds, being at an average speed of nearly 43 miles an hour. Before starting, the water in the tender had been heated to nearly boiling point; 16 cwt. of coke were consumed, or 44.8lb. per mile; 10,290lb. of water were evaporated, equal to 5.7lb. of water to 1lb. of coke.

Wilson’s engine, No. 27, was next tried. She weighed 24 tons 1 cwt., and her tender, loaded, 15 tons 13 cwt., the total load with train thus being 103 tons 14 cwt. William Carter drove the train, which left Derby at 7h. 10min. 20sec., and arrived at Masborough at 7h. 56min. 42sec., the speed averaging 52 miles an hour. The first 18 miles were negotiated in 22 minutes. 44¾ seconds, or at nearly 47 miles an hour. Only 13 cwt. of coke was used, equalling 36.4lb. per mile.

The following table shows the working of the two engines up the bank to the seventeenth mile-post:—

Trials were then made with trains of 17 coaches, weighted to 99 tons 16 cwt. Twenty passengers were carried, including Captain Symmons, the Government Inspector. The gross load was 101 tons.

William Mould drove the Sharp engine, and William Barrow the Wilson engine (No. 26).

The coke consumption was—Sharp’s, 16 cwt., or 44.8lb. per mile; Wilson’s, 12 cwt., or 33.6lb. per mile.

Water evaporated—Sharp’s, 10,840lb., equal to 27.1lb. per mile, or 6lb. of water by 1lb. of coke; Wilson’s, 10,116lb., equal to 25.29lb. per mile, or 7.5lb. of water by 1lb. of coke.

The first 18 miles up the bank were covered in 26 minutes 19 seconds by the “Jenny Lind,” and in 27 minutes 55 seconds by the “Jenny Sharp.”

The tables show the speeds at which the posts were passed:—

Beyond the thirtieth mile-post Wilson’s engine, which had been considerably in advance, according to the time taken, began to lose ground, in consequence of the driver allowing the fire to get low, and upon arrival at Masborough he had scarcely sufficient steam to shunt the train.

Mr. Kirtley considered the trial unsatisfactory for this reason, and a second one was arranged for the next day, but with no more satisfactory result, as upon this occasion, after travelling a mile, a joint cover of one of the cylinders worked loose, consequently a great deal of steam escaped during the remaining 39 miles of the trip. We have given the real facts in connection with the original “Jenny Linds” at some length, for the purpose of placing on permanent record the details of these capital locomotives, and so prevent our readers and students of locomotive history generally from being misled by the absurdly inaccurate romances that have, for some obscure purpose, been recently circulated concerning the “Jenny Lind.” (Fig. 44.)

The original design of the locomotive now to be described is so singular that we are reminded of the extravagant examples of locomotive construction appertaining to 1830, or thereabouts, rather than to the year how under review. Yet, strange as it may appear, the “Cornwall” (Fig. 45) is still running express trains, although it must be confessed it has undergone a complete metamorphosis since it was built at Crewe in 1847. The engine in question was designed by Mr. F. Trevithick, son of the famous “father of the locomotive,” and was intended to be a narrow-gauge improvement on Gooch’s famous “Great Western,” as Trevithick wished to build a locomotive that would be able to attain a higher rate of speed than the renowned broad-gauge engine. To do this, he considered an increase of the diameter of the driving wheels a sine qua non. He therefore constructed the “Cornwall” with driving wheels 8ft. 6in. in diameter. His next proposition was that as 8ft. was then considered the limit of size for driving wheels on the broad-gauge, with the boiler above the driving axle, it was necessary to place the boiler below the driving axle with wheels 8ft. 6in. diameter on the narrow-gauge. And, therefore, Trevithick constructed the “Cornwall,” with underhung boilers, i.e., beneath the driving axle. The cylinders were outside, 17½in. diameter, with a stroke of 24in. The heating surface was 1,046 sq. ft. The locomotive was carried on eight wheels—a group of four leading wheels, the driving, and a single pair of trailing wheels. Weight of engine in working order, 27 tons. The “Cornwall” was very successful in attaining high rates of speed, and, indeed, far exceeded Trevithick’s expectations in this respect.

It has been stated that she attained a speed equal to 117 miles an hour down the Madeley Bank. Such a statement must be accepted with reserve—not that the bonâ fides of the engineer who made it are doubted, but rather because of the difficulty of obtaining correctly the exact speed of engines when travelling at a great rate, even when proper instruments are employed. We know that with an ordinary watch correct results are almost impossible, and an error of a second or two when calculating a quarter of a mile will make a very great difference when arriving at the approximate rates in miles per hour. However, be this as it may, it is generally acknowledged that the “Cornwall” attained speeds that may fairly be called phenomenally high.

On November 9th, 1847, the “Cornwall” was hauling a goods train from Liverpool, and upon rounding the curve near Winsford Station, ran into a coal train, the result being the death of the driver of the “Cornwall,” the engine being thrown across both lines, whilst the tender and trucks were projected over the engine, and did not come to a standstill for several yards.

The “Cornwall” was one of the features of the first International Exhibition (held in Hyde Park, London, in 1851). In 1862 Mr. J. Ramsbottom rebuilt the “Cornwall,” and placed her new boiler over the driving wheels. She was numbered “173,” and still works the three-quarter-of-an-hour express trains between Liverpool and Manchester. She completed her jubilee of active service last year, and is still running. The present number of the “Cornwall” is “3020,” and she is now only a six-wheeled engine.

McConnell made an experiment in counterbalancing a locomotive on the London and North Western Railway in 1848. The engine in question was the “Snake,” No. 175, built by Jones and Potts on Stephenson’s long boiler principle. McConnell’s plan was to provide a connecting-rod attached to a block working between slide bars, on the opposite side of the driving axle to that on which the piston, etc., were located. By this method he considered that, providing his extra rod-block, etc., weighed the same as the pistons and other reciprocating parts, he had attained a perfect method of counterbalancing. The result was a rude disillusion of the idea, and a complete wreckage of both the theory and the “Snake,” the engine breaking down on its first trip, after being fitted with this reciprocating counterbalance. The only result of such an addition to the “Snake” was an increase in the weight of the engine and an augmentation of the friction and axle strains.

In the spring of 1848 McConnell built an engine which he expected “to prove the most powerful narrow-gauge engine ever yet built.”

It had outside cylinders 18in. diameter, and 7ft. 6in. between centres. The driving wheels were 6ft. diameter, leading and trailing 3ft. 10in. The boiler was 4ft. 3in. external diameter, 12ft. 7in. long, and contained 190 tubes of 2in. diameter. Height of top of boiler from rail level, 7ft. 9in.

The fire-box was 5ft. 9¼in. wide, by 5ft. 5in. long, and of the same height. The wheel base was as follows:—Leading to driving, 6ft. 8in.; driving to trailing, 10ft. 6in.

Another combination design in locomotive practice is to be found in engine “No. 185,” delivered to the York, Newcastle, and Berwick Railway on October 3rd, 1848, by R. Stephenson and Co.

This engine had inside cylinders, but outside valve gearing and eccentrics. The cylinders were 16in. diameter, with 20in. stroke. The boiler was 3ft. 10in. diameter and 11ft. long; there were 174 tubes, 1⅞in. outside diameter, and 11ft. long; the heating surface being: tubes, 964 sq. ft.; fire-box, 82 sq. ft. The driving wheels were 6ft. 6in. diameter, the leading and trailing being 3ft. 9in. diameter. Inside bearings were provided for the driving wheels and outside bearings for the leading and trailing wheels. Inside and outside iron-plate frames, 1in. thick and 8in. deep, were provided. This engine weighed 22 tons in working order, and consumed 18lb. of coke per mile with express trains of four carriages. The peculiar feature of “No. 185” was the vertical valves, worked by eccentrics outside the driving wheels; the pumps were also worked off the same eccentrics, and were consequently outside, as in the “Jenny Lind” design. The exhaust ports were below the cylinders, the pipes from which united at the blast orifice.