Lives of George and Robert Stephenson by Samuel Smiles: Part 2: Chapter 5

Chapter V. The Locomotive Engine. George Stephenson begins its improvement.

The rapid increase in the coal-trade of the Tyne about the beginning of the present century had the effect of stimulating the ingenuity of mechanics, and encouraging them to devise improved methods of transporting the coal from the pits to the shipping-places. From our introductory chapter, it will have been observed that the improvements which had thus far been effected were confined almost entirely to the road. The railway wagons still continued to be drawn by horses. By improving and flattening the tramway, considerable economy in horse-power had been secured; but, unless some more effective method of mechanical traction could be devised, it was clear that railway improvement had almost reached its limits.

Notwithstanding Trevithick's comparatively successful experiment with the first railway locomotive on the Merthyr Tydvil tram-road in 1804, described in a former chapter, he seems to have taken no farther steps to bring his invention into notice.

He was probably discouraged by the breakage of the cast-iron plates, of which the road was formed, which were crushed under the load of his engine, and could not induce the owners of the line to relay it with better materials so as to give his locomotive a fair trial.

An imaginary difficulty, also, seems to have tended, among other obstacles, to prevent the adoption of the locomotive, viz., the idea that, if a heavy weight were placed behind the engine, the "grip" or "bite" of its smooth wheels upon the equally smooth iron rail must necessarily be so slight that they would whirl round upon it, and, consequently, that the machine would not make any progress. Hence Trevithick, in his patent, provided that the periphery of the driving-wheels should be made rough by the projection of bolts or cross-grooves, so that the adhesion of the wheels to the road might thereby be better secured.

Trevithick himself does not seem to have erected another engine, but we gather from the evidence given by Mr. Rastrick in the committee on the Liverpool and Manchester Bill in 1825, that ten or twelve years before that time he had made an engine for Trevithick after his patent, and that the engine was exhibited in London. "A circular railroad was laid down," said Mr. Rastrick, and it was stated that this engine was to run against a horse, and that which went a sufficient number of miles was to win. It is not known what afterward became of this engine.

There were, however, at a much earlier period, several wealthy and enterprising men, both in Yorkshire and Northumberland, who were willing to give the locomotive a fair trial; and had Trevithick but possessed the requisite tenacity of purpose had he not been too soon discouraged by partially successful experiments he might have risen to both fame and fortune, not only as the inventor of the locomotive, but as the practical introducer of railway locomotion.

One of Trevithick's early friends and admirers was Mr. Blackett, of Wylam. The Wylam wagonway is one of the oldest in the north of England. Down to the year 1807 it was formed of wooden spars or rails, laid down between the colliery at Wylam where old Robert Stephenson worked and the village of Lemington, some four miles down the Tyne, where the coals were loaded into keels or barges, and floated down past Newcastle, to be shipped for London. Each chaldron-wagon had a man in charge of it, and was originally drawn by one horse. The rate at which the wagons were hauled was so slow that only two journeys were performed by each man and horse in one day, and three on the day following. This primitive wagon-way passed, as before stated, close in front of the cottage in which George Stephenson was born, and one of the earliest sights which met his infant eyes was this wooden tram-road worked by horses.

Mr. Blackett was the first colliery owner in the North who took an active interest in the locomotive. He had witnessed the first performances of Trevithick's steam-carriage in London, and was so taken with the idea of its application to railway locomotion that he resolved to have an engine erected after the new patent for use upon his tram-way at Wylam. He accordingly obtained from Trevithick, in October, 1804, a plan of his engine, provided with "friction wheels," and employed Mr. John Whinfield, of Pipewellgate, Gateshead, to construct it at his foundry there. The engine was made under the superintendence of one John Steele, an ingenious mechanic, who had been in Wales, and worked under Trevithick in fitting the engine at Pen-y-darran. When the Gateshead locomotive was finished, a temporary way was laid down in the works, on which it was run backward and forward many times. For some reason or other, however it is said because the engine was too light for drawing the coal-trains it never left the works, but was dismounted from the wheels, and set to blow the cupola of the foundry, in which service it long continued to be employed.

Several years elapsed before Mr. Blackett took any farther steps to carry out his idea. The final abandonment of Trevithick's locomotive at Pen-y-darran perhaps contributed to deter him from proceeding farther; but he had the Wylam wooden tram-way taken up in 1808, and a plate-way of cast iron laid down instead a single line furnished with sidings to enable the laden wagons to pass the empty ones. The new iron road proved so much smoother than the old wooden one, that a single horse, instead of drawing one, was enabled to draw two, or even three laden wagons.

Although the locomotive seemed about to be lost sight of, it was not forgotten. In 1811, Mr. Blenkinsop, the manager of the Middleton Collieries, near Leeds, revived the idea of employing it in lieu of horses to haul the coals along his tram-way. Mr. Blenkinsop, in the patent which he took out for his proposed engine, followed in many respects the design of Trevithick; but, with the help of Matthew Murray, of Leeds, one of the most ingenious mechanics of his day, he introduced several important and valuable modifications. Thus he employed two cylinders of 8 in. diameter instead of one, as in Trevithick's engine. These cylinders were placed vertically, and immersed for more than half their length in the steam space of the boiler. The eduction pipes met in a single tube at the top, and threw the steam into the air. The boiler was cylindrical in form, but of cast iron.

It had one flue, the fire being at one end and the chimney at the other. The engine was supported on a carriage without springs, resting directly upon two pairs of wheels and axles unconnected with the working parts, and which merely served to carry the engine upon the rails. The motion was effected in this way: the piston-rods, by means of cross-heads, worked the connecting rods, which came down to two cranks on each side below the boiler, placed at right angles in order to pass their centres with certainty. These cranks worked two shafts fixed across the engine, on which were small-toothed wheels working into a larger one between them; and on the axis of this large wheel, outside the framing, were the driving-wheels, one of which was toothed, and worked into a rack on one side of the railway.

It will be observed that the principal new features in this engine were the two cylinders and the toothed wheel working into a rack-rail. Mr. Blenkinsop contrived the latter expedient in order to insure sufficient adhesion between the wheel and the road, supposing that smooth wheels and smooth rails would be insufficient for the purpose. Clumsy and slow though the engine was compared with modern locomotives, it was nevertheless a success.

It was the first engine that plied regularly upon any railway, doing useful work; and it continued so employed for more than twenty years. What was more, it was a commercial success, for its employment was found to be economical compared with horsepower. In a letter to Sir John Sinclair, Mr. Blenkinsop stated that his engine weighed five tons; consumed two thirds of a hundred weight of coals and fifty gallons of water per hour; drew twenty-seven wagons, weighing ninety-four tons, on a dead level, at three and a half miles an hour, or fifteen tons up an ascent of 2 in. in the yard; then when "lightly loaded" it travelled at a speed of ten miles an hour; that it did the work of sixteen horses in twelve hours; and that its cost was £400. Such was Mr. Blenkinsop's own account of the performances of his engine, which was for a long time regarded as one of the wonders of the neighbourhood.

The Messrs. Chapman, of Newcastle, in 1812 endeavoured to overcome the same fictitious difficulty of the want of adhesion between the wheel and the rail by patenting a locomotive to work along the road by means of a chain stretched from one end of it to the other. This chain was passed once round a grooved barrel-wheel under the centre of the engine, so that when the wheel turned, the locomotive, as it were, dragged itself along the railway. An engine constructed after this plan was tried on the Heaton Railway, near Newcastle; but it was so clumsy in action, there was so great a loss of power by friction, and it was found to be so expensive and difficult to keep in repair, that it was very soon abandoned. Another remarkable expedient was adopted by Mr. Brunton, of the Butterley Works, Derbyshire, who in 1813 patented his Mechanical Traveller, to go upon legs working alternately like those of a horse. But this engine never got beyond the experimental state, for, at its very first trial, the driver, to make sure of a good start, overloaded the safety-valve, when the boiler burst and killed a number of the bystanders, wounding many more. These, and other contrivances with the same object, projected about the same time, show that invention was busily at work, and that many minds were anxiously labouring to solve the problem of steam locomotion on railways.

Mr. Blackett, of Wylam, was encouraged by the success of Mr. Blenkinsop's experiment, and again he resolved to make a trial of the locomotive upon his wagon-way. Accordingly, in 1812, he ordered a second engine, which was so designed as to work with a toothed driving-wheel upon a rack-rail as at Leeds. This while he was living at Brussels in 1816, a canal to Charleroi was under consideration, on which he seized the opportunity of urging the superior merits of a railway.

When he returned to England in 1820, he wrote a book upon the subject, entitled, "Observations on a General Iron Railway," in which he strongly advocated the advantages of railways generally, giving as a frontispiece to the book an engraving of Blenkinsop's engine. And several years after the opening of the Liverpool and Manchester Railway we find Thomas Gray, true to his first love, urging in the "Mechanics' Magazine" the superiority of Blenkinsop's cogged wheel and rail over the smooth road and rail of the modern railway locomotive as constructed by Thomas Waters, of Gateshead, under the superintendence of Jonathan Foster, Mr. Blackett's principal engine-wright. It was a combination of Trevithick's and Blenkinsop's engines; but it was of a more awkward construction than either. Like Trevithick's, it had a single cylinder with a fly-wheel, which Blenkinsop had discarded. The boiler was of cast iron. Jonathan Foster described it to the author in 1854 as "a strange machine, with lots of pumps, cog-wheels, and plugs, requiring constant attention while at work." The weight of the whole was about six tons.

When finished, it was conveyed to Wylam on a wagon, and there mounted upon a wooden frame, supported by four pairs of wheels, which had been constructed for its reception. A barrel of water, placed on another frame upon wheels, was attached to it as a tender. After a great deal of labour, the cumbrous machine was got upon the road. At first it would not move an inch. Its maker, Tommy Waters, became impatient, and at length enraged, and, taking hold of the lever of the safety-valve, declared in his desperation that "either she or he should go." At length the machinery was set in motion, on which, as Jonathan Foster described to the author, "she flew all to pieces, and it was the biggest wonder i' the world that we were not all blewn up." The incompetent and useless engine was declared to be a failure; it was shortly after dismounted and sold; and Mr. Blackett's praiseworthy efforts thus far proved in vain.

He was still, however, desirous of testing the practicability of employing locomotive power in working the coal down to Lemington, and he determined on making yet another trial. He accordingly directed his engine-wright, Jonathan Foster, to proceed with the building of a third engine in the Wylam workshops.

This new locomotive had a single 8-inch cylinder, was provided with a fly-wheel like its predecessor, and the driving-wheel was cogged on one side to enable it to travel in the rack-rail laid along the road. The engine proved more successful than the former one, and it was found capable of dragging eight or nine loaded wagons, though at the rate of little more than a mile an hour, from the colliery to the shipping-place. It sometimes took six hours to perform the journey of five miles. Its weight was found too great for the road, and the cast-iron plates were constantly breaking. It was also very apt to get off the rack-rail, and then it stood still. The driver was one day asked how he got on. "Get on?" said he, "we don't get on; we only get off!" On such occasions, horses had to be sent out to drag the wagons as before, and others to haul the engine back to the workshops.

It was constantly getting out of order; its plugs, pumps, or cranks got wrong, and it was under repair as often as at work. At length it became so cranky that the horses were usually sent after it to drag it along when it gave up, and the workmen generally declared it to be a "perfect plague." Mr. Blackett did not obtain credit among his neighbours for these experiments. Many laughed at his machines, regarding them only in the light of crotchets frequently quoting the proverb of "a fool and his money are soon parted." Others regarded them as absurd innovations on the established method of hauling coal, and pronounced that they would "never answer." Notwithstanding, however, the comparative failure of the second locomotive, Mr. Blackett persevered with his experiments, he was zealously assisted by Jonathan Foster, the enginewright, and William Hedley, the viewer of the colliery, a highly ingenious person, who proved of great use in carrying out the experiments to a successful issue.

One of the chief causes of failure being the rack-rail, the idea occurred to Mr. Hedley that it might be possible to secure sufficient adhesion between the wheel and the rail by the mere weight of the engine, and he proceeded to make a series of experiments for the purpose of determining this problem. He had a frame placed on four wheels, and fitted up with windlasses attached by gearing to the several wheels. The frame having been properly weighted, six men were set to work the windlasses, when it was found that the adhesion of the smooth wheels on the smooth rails was quite sufficient to enable them to propel the machine without slipping. Having then found the proportion which the power bore to the weight, he demonstrated by successive experiments that the weight of the engine would of itself produce sufficient adhesion to enable it to draw upon a smooth railroad the requisite number of wagons in all kinds of weather. And thus was the fallacy which had heretofore prevailed on this subject completely exploded, and it was satisfactorily proved that rack-rails, toothed wheels, endless chains, and legs, were alike unnecessary for the efficient traction of loaded wagons upon a moderately level road. From this time forward, considerably less difficulty was experienced in working the coal-trains upon the Wylam tram-road.

At length the rack-rail was dispensed with. The road was laid with heavier rails; the working of the old engine was improved; and a new engine was shortly after built and placed upon the road, still on eight wheels, driven by seven rack-wheels working inside them with a wrought-iron boiler through which the flue was returned so as largely to increase the heating surface, and thus give increased power to the engine.

By the year 1825, the progress made on the Wylam Railroad was thus described by Mr. Mackenzie in his "History of Northumberland:" "A stranger," said he, "is struck with surprise and astonishment on seeing a locomotive engine moving majestically along the road at the rate of four or five miles an hour, drawing along from ten to fourteen loaded wagons, weighing about 2 ?? tons; and his surprise is increased on witnessing the extraordinary facility with which the engine is managed. This invention is a noble triumph of science." As may readily be imagined, the jets of steam from the piston, blowing off into the air at high pressure while the engine was in motion, caused considerable annoyance to horses passing along the Wylam road, at that time a public highway. The nuisance was felt to be almost intolerable, and a neighbouring gentleman threatened to have it put down. To diminish the noise as much as possible, Mr. Blackett gave orders that so soon as any horse, or vehicle drawn by horses, came in sight, the locomotive was to be stopped, and the frightful blast of the engine thus suspended until the passing animals had got out of sight. Much interruption was thus caused to the working of the railway, and it excited considerable dissatisfaction among the workmen.

The following plan was adopted to abate the nuisance: a reservoir was provided immediately behind the chimney into which the waste steam was thrown after it had performed its office in the cylinder, and from this reservoir the steam gradually escaped into the atmosphere without noise. This arrangement was devised with the express object of preventing a blast in the chimney, the value of which, as we shall subsequently find, was not detected until George Stephenson, adopting it with a preconceived design and purpose, demonstrated its importance and value as being, in fact, the very life-breath of the locomotive engine.

While Mr. Blackett was thus experimenting and building locomotives at Wylam, George Stephenson was anxiously studying the same subject at Killingworth. He was no sooner appointed engine-wright of the collieries than his attention was directed to the means of more economically hauling the coal from the pits to the river side. We have seen that one of the first important improvements which he made, after being placed in charge of the colliery machinery, was to apply the surplus power of a pumping steam-engine fixed underground, for the purpose of drawing the coals out of the deeper workings of the Killingworth mines, by which he succeeded in effecting a large reduction in the expenditure on manual and horse labour.

The coals, when brought above ground, had next to be laboriously dragged by means of horses to the shipping staiths on the Tyne, several miles distant. The adoption of a tram-road, it is true, had tended to facilitate their transit; nevertheless, the haulage was both tedious and expensive. With the view of economizing labour, Stephenson laid down inclined planes where the nature of the ground would admit of this expedient being adopted.

Thus a train of full wagons let down the incline by means of a rope running over wheels laid along the tram-road, the other end of which was attached to a tram of empty wagons placed at the bottom of the parallel road on the same incline, dragged them up by the simple power of gravity. But this applied only to a comparatively small part of the road. An economical method of working the coal-trains, instead of by means of horses the keep of which was at that time very costly, in consequence of the high price of corn was still a great desideratum,-and the best practical minds in the collieries were actively engaged in trying to solve the problem.

In the first place, Stephenson resolved to make himself thoroughly acquainted with what had already been done. Mr. Blackett's engines were working daily at Wylam, past the cottage where he had been born, and thither he frequently went to inspect the improvements made by Mr. Blackett from time to time both in the locomotive and in the plate-way along which it worked. Jonathan Foster informed us that, after one of these visits, Stephenson declared to him his conviction that a much more effective engine might be made, that should work more steadily and draw the load more effectively.

He had also the advantage, about the same time, of seeing one of Blenkinsop's Leeds engines, which was placed on the tramway leading from the collieries of Kenton and Coxlodge, on the 2d of September, 1813. This locomotive drew sixteen chaldron wagons, containing an aggregate weight of seventy tons, at the rate of about three miles an hour. George Stephenson and several of the Killingworth men were among the crowd of spectators that day; and after examining the engine and observing its performances, he remarked to his companions that "he thought he could make a better engine than that, to go upon legs." Probably he had heard of the invention of Brunton, whose patent had by this time been published, and proved the subject of much curious speculation in the colliery districts. Certain it is that, shortly after the inspection of the Coxlodge engine, he contemplated the construction of a new locomotive, which was to surpass all that had preceded it. He observed that those engines which had been constructed up to this time, however ingenious in their arrangements, were in a great measure practical failures. Mr. Blackett's was as yet both clumsy and expensive. Chapman's had been removed from the Heaton tram-way in 1812, and was regarded as a total failure. And the Blenkinsop engine at Coxlodge was found very unsteady and costly in its working; besides, it pulled the rails to pieces, the entire strain being upon the rack-rail on one side of the road. The boiler, however, having shortly blown up, there was an end of that engine, and the colliery owners did not feel encouraged to try any farther experiment.

An efficient and economical working locomotive engine, therefore, still remained to be invented, and to accomplish this object Stephenson now applied himself. Profiting by what his predecessors had done, warned by their failures and encouraged by their partial successes, he commenced his labours. There was still wanting the man who should accomplish for the locomotive what James Watt had done for the steam-engine, and combine in a complete form the best points in the separate plans of others, embodying with them such original inventions and adaptations of his own as to entitle him to the merit of inventing the working locomotive, as James Watt is to be regarded as the inventor of the working condensing engine. This was the great work upon which George Stephenson now entered, though probably without any adequate idea of the ultimate importance of his labours to society and civilization.

He proceeded to bring the subject of constructing a "Travelling Engine," as he then denominated the locomotive, under the notice of the lessees of the Killingworth Colliery, in the year 1813. Lord Ravensworth, the principal partner, had already formed a very favourable opinion of the new colliery, engine-wright from the improvements which he had effected in the colliery engines, both above and below ground; and, after considering the matter, and hearing Stephenson's explanations, he authorized him to proceed with the construction of a locomotive, though his lordship was by some called a fool for advancing money for such a purpose. "The first locomotive that I made," said Stephenson, many years after, when speaking of his early career at a public meeting in Newcastle, "was at Killingworth Colliery, and with Lord Ravensworth's money. Yes, Lord Havensworth and partners were the first to intrust me, thirty-two years since, with money to make a locomotive engine. I said to my friends, there was no limit to the speed of such an engine, if the works could be made to stand." Our enginewright had, however, many obstacles to encounter before he could get fairly to work with the erection of his locomotive. His chief difficulty was in finding workmen sufficiently skilled in mechanics and in the use of tools to follow his instructions and embody his designs in a practical shape. The tools then in use about the collieries were rude and clumsy, and there were no such facilities as now exist for turning out machinery of an entirely new character. Stephenson was under the necessity of working with such men and tools as were at his command, and he had in a great measure to train and instruct the workmen himself. The engine was built in the workshops at the West Moor, the leading mechanic being John Thirlwall, the colliery blacksmith, an excellent mechanic in his way, though quite new to the work now intrusted to him.

In this first locomotive constructed at Killingworth, Stephenson to some extent followed the plan of Blenkinsop's engine. The wrought-iron boiler was cylindrical, eight feet in length and thirty-four inches in diameter, with an internal flue-tube twenty inches wide passing through it. The engine had two vertical cylinders of eight inches diameter and two feet stroke let into the boiler, which worked the propelling gear with cross-heads and connecting-rods. The power of the two cylinders was combined by means of spur-wheels, which communicated the motive power to the wheels supporting the engine on the rail, instead of, as in Blenkinsop's engine, to cog-wheels which acted on the cogged rail independent of the four supporting wheels. The engine thus worked upon what is termed the second motion. The chimney was of wrought iron, round which was a chamber extending back to the feed-pumps, for the purpose of heating the water previous to its injection into the boiler. The engine had no springs, and was mounted on a wooden frame supported on four wheels. In order to neutralize as much as possible the jolts and shocks which such an engine would necessarily encounter from the obstacles and inequalities of the then very imperfect plateway, the water-barrel which served for a tender was fixed to the end of a lever and weighted, the other end of the lever being connected with the frame of the locomotive carriage. By this means the weight of the two was more equally distributed, though the contrivance did not by any means compensate for the total absence of springs.

The wheels of the locomotive were all smooth, Stephenson having satisfied himself by experiment that the adhesion between the wheels of a loaded engine and the rail would be sufficient for the purpose of traction. Robert Stephenson informed us that his father caused a number of workmen to mount upon the wheels of a wagon moderately loaded, and throw their entire weight upon the spokes on one side, when he found that the wagon could thus be easily propelled forward without the wheels slipping. This, together with other experiments, satisfied him, as it had already satisfied Mr. Hedley, of the expediency of adopting smooth wheels on his engine, and it was so made accordingly.

The engine was, after much labour and anxiety, and frequent alterations of parts, at length brought to completion, having been about ten months in hand. It was placed upon the Killingworth Railway on the 25th of July, 1814, and its powers were tried on the same day. On an ascending gradient of 1 in 450, the engine succeeded in drawing after it eight loaded carriages of thirty tons' weight at about four miles an hour; and for some time after it continued regularly at work.

Although a considerable advance upon previous locomotives, "Blucher" (as the engine was popularly called) was nevertheless a somewhat cumbrous and clumsy machine. The parts were huddled together. The boiler constituted the principal feature; and, being the foundation of the other parts, it was made to do duty not only as a generator of steam, but also as a basis for the fixings of the machinery and for the bearings of the wheels and axles. The want of springs was seriously felt; and the progress of the engine was a succession of jolts, causing considerable derangement to the machinery. The mode of communicating the motive power to the wheels by means of the spur-gear also caused frequent jerks, each cylinder alternately propelling or becoming propelled by the other, as the pressure of the one upon the wheels became greater or less than the pressure of the other; and, when the teeth of the cog-wheels became at all worn, a rattling noise was produced during the travelling of the engine.

As the principal test of the success of the locomotive was its economy as compared with horse-power, careful calculations were made with the view of ascertaining this important point. The result was, that it was found the working of the engine was at first barely economical; and at the end of the year the steam power and the horse-power were ascertained to be as nearly as possible upon a par in point of cost.

"We give the remainder of the history of George Stephenson's efforts to produce an economical working locomotive in the words of his son Robert, as communicated to the author in 1856, for the purposes of his father's "Life." –

"A few months of experience and careful observation upon the operation of this (his first) engine convinced my father that the complication arising out of the action of the two cylinders being combined by spur-wheels would prevent their coming into practical application. He then directed his attention to an entire change in the construction and mechanical arrangements, and in the following year took out a patent, dated February 28th, 1815, for an engine which combined in a remarkable degree the essential requisites of an economical locomotive that is to say, few parts, simplicity in their action, and great simplicity in the mode by which power was communicated to the wheels supporting the engine.

"This second engine consisted as before of two vertical cylinders, which communicated directly with each pair of the four wheels that supported the engine by a cross-head and a pair of connecting-rods; but, in attempting to establish a direct communication between the cylinders and the wheels that rolled upon the rails, considerable difficulties presented themselves. The ordinary joints could not be employed to unite the engine, which was a rigid mass, with the wheels rolling upon the irregular surface of the rails; for it was evident that the two rails of the line of railway could not always be maintained at the same level with respect to each other that one wheel at the end of the axle might be depressed into a part of the line which had subsided, while the other would be elevated. In such a position of the axle and wheels it was clear that a rigid communication between the cross-head and the wheels was impracticable. Hence it became necessary to form a joint at the top of the piston-rod where it united with the cross-head, so as to permit the cross-head always to preserve complete parallelism with the axle of the wheels with which it was in communication.

" In order to obtain the flexibility combined with direct action which was essential for insuring power and avoiding needless friction and jars from irregularities in the rail, my father employed the ' ball and socket' joint for effecting a union between the ends of the cross-heads where they united with the connecting-rods, and between the end of the connecting-rods where they were united with the crank-pins attached to each driving-wheel. By this arrangement the parallelism between the cross-head and the axle was at all times maintained, it being permitted to take place without producing jar or friction upon any part of the machine.

" The next important point was to combine each pair of wheels by some simple mechanism, instead of the cog-wheels which had formerly been used. My father began by inserting each axle into two cranks at right angles to each other, with rods communicating horizontally between them. An engine was made on this plan, and answered extremely well. But at that period (1815) the mechanical skill of the country was not equal to the task of forging cranked axles of the soundness and strength necessary to stand the jars incident to locomotive work; so my father was compelled to fall back upon a substitute which, though less simple and less efficient, was within the mechanical capabilities of the workmen of that day, either for construction or repair. He adopted a chain which rolled over indented wheels placed on the centre of each axle, and so arranged that the two pairs of wheels were effectually coupled and made to keep pace with each other. But these chains after a few years' use became stretched, and then the engines were liable to irregularity in their working, especially in changing from working back to forward again. Nevertheless, these engines continued in profitable use upon the Killingworth Colliery Railway for some years. Eventually the chain was laid aside, and the front and hind wheels were united by rods on the outside, instead of by rods and crank-ankles inside, as specified in the original patent; and this expedient completely answered the purpose required, without involving any expensive or difficult workmanship.

"Another important improvement was introduced in this engine. The eduction steam had hitherto been allowed to escape direct into the open atmosphere; but my father, having observed the great velocity with which the waste-steam escaped, compared with the velocity with which the smoke issued from the chimney of the same engine, thought that by conveying the eduction steam into the chimney, and there allowing it to escape in a vertical direction, its velocity would be imparted to the smoke from the engine, or to the ascending current of air in the chimney. The experiment was no sooner made than the power of the engine became more than doubled; combustion was stimulated, as it were, by a blast; consequently, the power of the boiler for generating steam was increased, and, in the same proportion, the useful duty of the engine was augmented.

"Thus, in 1815, my father had succeeded in manufacturing an engine which included the following important improvements on all previous attempts in the same direction: simple and direct communication between the cylinder and the wheels rolling upon the rails; joint adhesion of all the wheels, attained by the use of horizontal connecting-rods; and, finally, a beautiful method of exciting the combustion of fuel by employing the waste steam which had formerly been allowed uselessly to escape. It is, perhaps, not too much to say that this engine, as a mechanical contrivance, contained the germ of all that has since been effected. It may be regarded, in fact, as a type of the present locomotive engine.

"In describing my father's application of the waste steam for the purpose of increasing the intensity of combustion in the boiler, and thus increasing the power of the engine without adding to its weight, and while claiming for this engine the merit of being a type of all those which have been successfully devised since the commencement of the Liverpool and Manchester Railway, it is necessary to observe that the next great improvement in the same direction, the 'multitubular boiler,' which took place some years later, could never have been used without the help of that simple expedient, the steam-blast, by which power only the burning of coke was rendered possible.

" I can not pass over this last-named invention of my father's without remarking how slightly, as an original idea, it has been appreciated; and yet how small would be the comparative value of the locomotive engine of the present day without the application of that important invention!

"Engines constructed by my father in the year 1818 upon the principles just described are in use on the Killingworth Colliery Railway to this very day (1856), conveying, at the speed of perhaps five or six miles an hour, heavy coal-trains, probably as economically as any of the more perfect engines now in use.

"There was another remarkable piece of ingenuity in this machine, which was completed so many years before the possibility of steam-locomotion became an object of general commercial interest and Parliamentary inquiry. I have before observed that up to and after the year 1818 there was no such class of skilled mechanics, nor were there such machinery and tools for working in metals, as are now at the disposal of inventors and manufacturers. Among other difficulties of a similar character, it was not possible at that time to construct springs of sufficient strength to support the improved engines. The rails then used being extremely light, the roads became worn down by the traffic, and occasionally the whole weight of the engine, instead of being uniformly distributed over four wheels, was thrown almost diagonally upon two. In order to avoid the danger arising from such irregularities in the road, my father arranged the boiler so that it was supported upon the frame of the engine by four cylinders which opened into the interior of the boiler. These cylinders were occupied by pistons with rods, which passed downward and pressed upon the upper side of the axles. The cylinders, opening into the interior of the boiler, allowed the pressure of steam to be applied to the upper side of the piston, and that pressure being nearly equal to the support of one fourth of the weight of the engine, each axle, whatever might be its position, had the same amount of weight to bear, and consequently the entire weight was at all times nearly equally distributed among the wheels. This expedient was more necessary in this case, as the weight of the new locomotive engines far exceeded that of the carriages which had hitherto been used upon colliery railways, and therefore subjected the rails to much greater risk from breakage. And this mode of supporting the engine remained in use until the progress of spring-making had considerably advanced, when steel springs of sufficient strength superseded this highly ingenious mode of distributing the weight of the engine uniformly among the wheels."

The invention of the Steam-blast by George Stephenson in 1815 was fraught with the most important consequences to railway locomotion, and it is not saying too much to aver that the success of the locomotive has been in a great measure the result of its adoption. Without the steam-blast, by means of which the intensity of combustion is maintained at its highest point, producing a correspondingly rapid evolution of steam, high rates of speed could not have been kept up; the advantages of the multitubular boiler (afterward invented) could never have been fully tested; and locomotives might still have been dragging themselves unwieldily along at little more than five or six miles an hour.

As this invention has been the subject of considerable controversy, it becomes necessary to add a few words respecting it in this place. It has been claimed as the invention of Trevithick in 1804, of Hedley in 1814, of Goldsworthy Gurney in 1820, and of Timothy Hackworth in 1829. With respect to Trevithick, it appears that he discharged the waste steam into the chimney of his engine, but without any intention of thereby producing a blast; and that he attached no value to the expedient is sufficiently obvious from the fact that in 1815 he took out a patent for urging the fire by means of fanners, similar to a winnowing machine. The claim put forward on behalf of William Hedley, that he invented the blast-pipe for the Wylam engine, is sufficiently contradicted by the fact that the Wylam engine had no blast-pipe. "I remember the Wylam engine," Robert Stephenson wrote to the author in 1857, "and I am positive there was no blast-pipe." On the contrary, the Wylam engine embodied a contrivance for the express purpose of preventing a blast. This is clearly shown by the drawing and description of it contained in the first edition of Nicholas Wood's "Practical Treatise on Railroads," published in 1825. This evidence is all the more valuable for our purpose as it was published long before any controversy had arisen as to the authorship of the invention, and, indeed, before it was believed that any merit whatever belonged to it. And it is the more remarkable, as Nicholas Wood himself, who published the first practical work on railways, did not at that time approve of the steam-blast, and referred to the Wylam engine in illustration of how it might be prevented.

The following passage from Mr. Wood's book clearly describes the express object and purpose for which George Stephenson invented and applied the steam-blast in the Killingworth engines.

Describing their action, Mr. Wood says: "The steam is admitted to the top and bottom of the piston by means of a sliding valve, which, being moved up and down alternately, opens a communication between the top and bottom of the cylinder and the pipe that is open into the chimney and turns up within it. The steam, after performing its office within the cylinder, is thus thrown into the chimney, and the power with which it issues will be proportionate to the degree of elasticity; and the exit being directed upward, accelerates the velocity of the current of heated air accordingly.

And again, at another part of the book, he says: "There is another great objection urged against locomotives, which is, the noise that the steam makes in escaping into the chimney; this objection is very singular, as it is not the result of any inherent form in the organization of such engines, but an accidental circumstance. When the engines were first made, the steam escaped into the atmosphere, and made comparatively little noise; it was found difficult then to produce steam in sufficient quantity to keep the engine constantly working, or rather to obtain an adequate rapidity of current in the chimney to give sufficient intensity to the fire. To effect a greater rapidity, or to increase the draught of the chimney, Mr. Stephenson thought that by causing the steam to escape into the chimney through a pipe with its end turned upward, the velocity of the current would be accelerated, and such was the effect; but, in remedying one evil, another has been produced, which, though objectionable in some places, was not considered as objectionable on a private railroad. The tube through the boiler having been increased, there is now no longer any occasion for the action of the steam to assist the motion of the heated air in the chimney.

The steam thrown in this manner into the chimney acts as a trumpet, and certainly makes a very disagreeable noise. Nothing, however, is more easy to remedy, and the very act of remedying this defect will also be the means of economizing the fuel."

Mr. Wood then proceeds to show how the noise caused by the blast how, in fact, the blast itself, might be effectually prevented by adopting the expedient employed in the Wylam engine; which was, to send the exhaust steam, not into the chimney (where alone the blast could act with effect by stimulating the draught), but into a steam-reservoir provided for the purpose. His words are these: "Nothing more is wanted to destroy the noise than to cause the steam to expand itself into a reservoir, and then allow it to escape gradually to the atmosphere through the chimney. Upon the Wylam railroad the noise was made the subject of complaint by a neighbouring gentleman, and they adopted this mode, which had the effect above mentioned."

It is curious to find that Mr. Nicholas Wood continued to object to the use of the steam-blast down even to the time when the Liverpool and Manchester Railway Bill was before Parliament. In his evidence before the Committee on that Bill in 1825, he said: "Those engines [at Killingworth] puff very much, and the object is to get an increased draught in the chimney.

Now (by enlarging the flue-tube and giving it a double turn through the boiler) we have got a sufficiency of steam without it, and I have no doubt, by allowing the steam to exhaust itself in a reservoir, it would pass quietly into the chimney without that noise." In fact, Mr. Wood was still in favour of the arrangement adopted in the Wylam engine, by which the steam-blast had been got rid of altogether.

If these statements, made in Mr. Wood's book, be correct and they have never been disputed they render it perfectly clear that George Stephenson invented and applied the steam-blast for the express purpose of quickening combustion in the furnace by increasing the draught in the chimney. Although urged by Wood to abandon the blast, Stephenson continued to hold by it as one of the vital powers of the locomotive engine. It is quite true that in the early engines, with only a double flue passing through the boiler, run as they were at low speeds, the blast was of comparatively less importance. It was only when the improved passenger engine, fitted with the multi-tubular boiler, was required to be run at high speeds that the full merits of the blast were brought out; and in detecting its essential uses in this respect, and sharpening it for the purpose of increasing its action, the sagacity of Timothy Hackworth, of Darlington, is entitled to due recognition.

See Also

• Lives of George and Robert Stephenson by Samuel Smiles
• Lives of George and Robert Stephenson by Samuel Smiles: Part 2: Chapter 4
• Lives of George and Robert Stephenson by Samuel Smiles: Part 2: Chapter 6