Every-day Science: Volume 7. The Conquest of Time and Space

The passenger coach on this first train, the first of its kind ever constructed for the special purpose of carrying passengers, was remarkable for its simplicity. One writer described it as "a modest and uncouth-looking affair, made more for strength than for beauty. A row of seats ran along each side of the interior, and a long table was fixed in the centre, the access being by the doorway behind, like an omnibus. This vehicle was named the Experiment, and was the only carriage for passengers upon the road for some time."

About this time the now famous Liverpool and Manchester Railway was projected. It was elaborately planned and carried out at an enormous expense. The construction of the road-bed was given special attention, although as yet the question of what motive power should be used had not been decided. Most of the directors and engineers favored the use of horses. The few that were in favor of steam did not favor the use of locomotives, but a system that would now be called a relay-cable system. According to this plan the road of about thirty miles was to be divided into nineteen sections, over each of which a stationary steam-engine was to work a chain or cable. But when the board of engineers appointed to investigate the possibilities of this system reported on the matter, it was found that there were several vital defects in such a system. For example, should any one of the sections of cable break or become inoperative, the entire line would have to stand idle; and furthermore, the cost of building and maintaining these nineteen stations offered serious financial obstacles.

It is an interesting fact that until the report of this board was made "not a single professional man of eminence could be found who preferred the locomotive over the fixed engine, George Stephenson only excepted." But with the glaring defects of the cable road, and the enormous cost of maintenance impressed upon the directors, the idea of the locomotive became at once more attractive, and the performance of Stephenson's locomotive was more carefully investigated. The upshot of these investigations was the offer of a prize of £500 for a locomotive that, on a certain day would perform certain duties named under the eight following headings:—

1. The engine must effectually consume its own smoke.

2. The engine, if of six tons' weight, must be able to draw, day by day, twenty tons' weight, including the tender, and water-tank, at ten miles an hour, with a pressure of steam upon the boiler not exceeding fifty pounds to the square inch.

3. The boiler must have two safety-valves, neither of which must be fastened down, and one of them completely out of the control of the engineer.

4. The engine and boiler must be supported upon springs and rest on six wheels, the height of the whole not exceeding fifteen feet to the top of the chimney.

5. The engine with water must not weigh more than six tons, but an engine of less weight would be preferred although drawing a proportionately less load behind it; if of only four and one-half tons it might be put on four wheels.

6. A mercurial gauge must be affixed to the machine, showing the steam pressure about forty-five pounds to the square inch.

7. The engine must be delivered, complete and ready for trial, at the Liverpool end of the railway, not later than October 1, 1829.

8. The price of the engine must not exceed £550.

What strikes one as most peculiar in this set of requirements and specifications is the first clause—that of the engine consuming its own smoke; for even at the present time this is considered a difficult problem. But this was not so considered by the inventors of that time, their great stumbling-block being the high speed required. Ten miles an hour struck most of them as absurd and out of the question.

One eminent person, who was to become later one of England's leading engineers, stated publicly that "if it proved to be possible to make a locomotive go ten miles an hour, he would undertake to eat a stewed engine-wheel for his breakfast." It is not recorded whether or not this terrible threat was carried out.

But there was more than one engineer and engine-builder who took a more sanguine view of the prize offer. The firm of Braithwait & Ericsson signified its intention of competing, with a locomotive that they named the Novelty. Another firm entered the contest with an engine called the Sans-pareil; still another firm entered the Perseverance; and George Stephenson was on hand with the now-famous Rocket.

In the series of trials that followed, the Sans-pareil and the Perseverance were so clearly outclassed by the other two competing locomotives that they need not be considered here; but the Novelty and the Rocket were close competitors. The Novelty, indeed, made such a good showing, and afterwards proved to be such a good locomotive, that although it lost the contest, many competent judges have since regarded it as equal to the Rocket, if not superior, in principle. Be that as it may, later experiments proved conclusively that the cause of failure on the final day of the prize contest was due to defects in workmanship rather than to defective principle of construction.

The Novelty has been described as having the appearance of "a milk-can set in the rear end of a wagon, with a little smokestack in front looking like a high dashboard." It carried its supply of fuel and water in the "wagon-box" part of the engine frame, in front of the boiler, so that it required no tender. On its first trial, running without any load, it reached a speed of twenty-four miles an hour—a speed more than double the "stewed engine-wheel" limit. But at each subsequent trial, although it hauled loads for short distances, some part of its machinery became disabled, so that it was necessarily regarded as inferior to its more stable rival, the Rocket.

The Sans-pareil was considerably over the maximum weight and according to a strict interpretation of the stipulations, should not have been allowed to contest; but although this question of over-weight was waived by the judges, and the engine given a fair trial, it showed such a capacity for consuming fuel without any corresponding ability to perform work, that it was decided inferior to the Novelty and the Rocket. The Perseverance was clearly outclassed by all the other competing engines, as its maximum speed was only five or six miles an hour.

The most consistent performer, and the final prize-winner, as everyone knows, was Stephenson's Rocket, the direct ancestor of all modern locomotives. The boiler of this locomotive was horizontal, as in modern locomotives, cylindrical, and had flat ends. It was six feet in length and a little over three feet in diameter. The upper half of the boiler was used as a reservoir for steam, the lower half being filled with water and having copper pipes running through it. The fire-box, two feet wide and three feet high, was placed immediately behind the boiler. Just above this, and on each side, were the cylinders, two in number, acting obliquely downward on the two front wheels of the engine, the piston-rod connecting with the driver by a bar pinned to the outside of the wheel, as in modern American locomotives.

The engine with its load of water weighed a trifle over four tons—seemingly little more than a toy-locomotive, as compared with the modern monsters more than thirty times that weight. But for its size the little Rocket was a marvelous performer, even as judged by recent standards. On the first day of the contests over the two miles of trial tracks, it covered twelve miles in considerably less than an hour, shuttling back and forth over the road. The next day, as none of the other engines was in condition to exhibit, Stephenson offered to satisfy the curiosity of the great crowd that had gathered—a crowd that contained representatives from all over the world—by an unofficial trial of the Rocket. He coupled the little engine to a car, loaded on thirty-six passengers, and took them for a spin over the road at the rate of from twenty-six to thirty miles an hour.

The following day some of the competing locomotives were still unable to exhibit, and again the Rocket was given a semi-official trial. Hauling a car loaded with thirteen tons' weight, it ran back and forth over the two-mile road, covering thirty-five miles in one hour and forty-eight minutes including stoppages. The maximum velocity attained was about twenty-nine miles an hour. As this performance was duplicated on the day of the official trial, the Rocket was declared the winner, and awarded the prize.

Naturally there were many minor defects in the construction of this first locomotive, although most of them were too trivial and unimportant to affect the excellence of the machine as a whole. But it had one serious defect: the inclination of the cylinders caused the entire machine to rise and fall on its springs at every double stroke, producing great unsteadiness when running at any considerable speed. This was corrected a few months later by the suggestion of Timothy Hackworth, who drew plans for a locomotive having horizontal cylinders to be used on the Stockton & Darlington Railway. His plans were submitted to Stephenson, who constructed an engine from them called the Globe, which differed from the Rocket in having the cylinders not only horizontal, but placed on the inside of the wheels. A little later Stephenson built the Planet on much the same lines as the Globe, and this engine became the model for engine builders the world over. It is an interesting fact that American engineers adopted, and still cling to, Stephenson's original plan of having the cylinders act on rods attached to the outside of the wheels as in the Rocket, while English engineers have always built their locomotives with the cylinders on the inside, as arranged on the Planet.

Since the time of the Planet the general shape and arrangement of most locomotives has remained unchanged. In America the inclemencies of the climate compelled the invention of the cab; and it was here also that the bell, whistle, pilot, and sand-box were first introduced. But by 1850 the present type of locomotive had been produced; and although constant modifications are being introduced, the general appearance of the locomotive remains the same, the difference being mostly in the bulk.

IMPROVEMENTS IN LOCOMOTIVES IN RECENT YEARS

During the closing years of the nineteenth century the general improvements in the rolling-stock of railroads, and the constantly increasing demand for faster passenger service, stimulated manufacturers to attempt numerous improvements as well as many changes in the size of the more recent types of locomotives. In a general way these changes may be summarized as follows: A great increase in the size and weight, with increased speed and tractive power; the use of larger boilers with thicker shells; the substitution of steel for cast-iron in certain parts of the locomotive, thereby greatly increasing the strength; and finally, the economizing of steam by compounding.

There is no way of determining the exact amount of increase in the weight of engines during the last decade, but the figures of some of the great manufacturing establishments will give a fair idea of this increase in a general way. In one of these establishments the average weight of a locomotive turned out ten years ago was 92,000 pounds for the engine alone, without the tender. At the present time the engines being manufactured by the same firm average 129,000 pounds, an increase of 37,000 pounds, or something over forty per cent. This average weight, however, gives but an inadequate conception of the size of the largest locomotives now being manufactured. The "hundred-ton" engine has become a commonplace. In 1909 a locomotive weighing, with its tenders, 300 tons was manufactured for passenger traffic on the Santa Fé lines.

In America there seems to be no limit to the sizes that may be reached; or at least up to the present time this limit has not been attained. In England and several of the Continental countries a great difficulty has been found to exist in the unlimited size of locomotives, in the fact that the bridges and tunnels of these railroads are, almost without exception, so low that any very great vertical increase in the size of the engine is out of the question without reconstructing many miles of bridges and tunnels at an enormous cost.

The increased demand for greater speed has also caused a marked increase in the amount of steam pressure per square inch in the boilers. In 1870 the average was about 130 pounds; by 1890 this had been increased to about 160 pounds; while at the present time steam is used frequently at a pressure of 225 pounds. Naturally this increase in pressure compels the use of heavier steel boiler plates. In 1890 the usual thickness of the steel sheets was one-half inch; but at the present time it is no unusual thing to use plates seven-eighths of an inch in thickness.

But probably the most important improvement in locomotive construction in recent years is the introduction of the compounding principle in the use of steam—a system whereby practically the entire energy of the steam is utilized, instead of a considerable portion of it being a dead loss, as in the older type of engine. As every one knows, the passage of the steam through a single cylinder of an engine does not exhaust its entire energy. In the compounding system this exhausted steam is made to pass through one or more cylinders after coming from the first, the energy of all these cylinders being utilized for the production of power.

The application of this principle of compounding is not new even in the field of locomotive construction. As early as 1846 patents for a compound locomotive were taken out in the United States, and such an engine built in 1867; but it is only since 1890 that compound locomotives have become popular in this country. In these compound locomotives the two cylinders are of unequal diameter, so proportioned "that the steam at high pressure in the smaller cylinder exerts upon the piston approximately the same force that is exerted by steam at a lower pressure in the larger cylinder. Steam is admitted first into the smaller cylinder, where it expends a portion of its initial energy, and then passes into the larger cylinder, where it performs an equal amount of work by exerting a diminished pressure upon a larger surface. This is the principle of compounding, the relative sizes and positions of the cylinders being varied according to the conditions to be met by the engine, or the ideas of the designer or builder, or of the purchaser. While in the marine and stationary engine the compound principle has been carried with success and economy to three and four stages of expansion in the use of steam, it has not been found practicable to go beyond two stages in compound locomotives."

In a pamphlet issued recently by one of the leading locomotive works of the country, some points of interest concerning the compound locomotive were stated concisely as follows:

"In stationary-engine practice the chief measure of the boiler efficiency is the economical consumption of coal. In most stationary engines the boilers are fired independently, and the draft is formed from causes entirely separate and beyond the control of the escape of steam from the cylinders. Hence any economy shown by the boilers must of necessity be separate and distinct from that which may be effected by the engine itself. In a locomotive, however, the amount of work depends entirely upon the weight on the driving wheels, the cylinder dimensions being proportioned to this weight, and, whether the locomotive is compound or single expansion, no larger boiler can be provided, after allowing for the wheels, frame and mechanism, than the total limit of weight permits. The heating surface and grate areas in both compound and single-expansion locomotives of the same class are practically the same, and the evaporative efficiency of both locomotives is chiefly determined by the action of the exhaust, which must be of sufficient intensity in both cases to generate the amount of steam necessary for utilizing to the best advantage the weight on the driving wheels. This is a feature that does not appear in any stationary engine, so that the compound locomotive cannot be judged by stationary standards, and the only true comparison to be made is between locomotives of similar construction and weight, equipped in one case with compound and in the other with single-expansion cylinders.

"No locomotive, compound or single-expansion, will haul more than its adhesion will allow. The weight on driving wheels is the limiting factor in the problem which confronts the locomotive engineer. Power can, of course, be increased by building a larger engine and augmenting this weight but in the present construction of tracks and bridges the limit of driving wheel load has almost been reached. Hence in modern locomotive practice the goal before the designer and engineer is to obtain maximum efficiency for the minimum weight admissible.

"It is not claimed for compound locomotives that a heavier train can be hauled at a given speed than with a single-expansion locomotive of similar weight and class; but the compound will, at very slow speed, on heavy grades, keep a train moving where a single-expansion will slip and stall. This is due to the pressure on the crank-pins of the compound being more uniform throughout the stroke than in the case of the single-expansion locomotive, and also to the fact that, when needed, live steam can be admitted to the low-pressure cylinders."

Of course, the principal reason for compounding the locomotive is to economize steam, and this is unquestionably accomplished; but nevertheless the comparative economy of compound and single-expansion locomotives was for some time a mooted question. Numerous tests have been made with these two classes of engines, and the widest ranges of differences were shown in many instances. In some cases the compounds seem to show a saving of some forty per cent. in fuel; but this is by no means a determinative factor in the daily use of an engine. It is found that repairs on the compound are more difficult to make, and consequently more expensive than on the single-expansion engines; but on the whole it is very generally conceded that the compound saves its owners from ten to twenty-five per cent. over the older type.

The rapid increase of the size, and consequent coal-consuming capacity, of the modern locomotive has added another problem to engineering—that of keeping the yawning maw of the fire-box supplied with coal. There is a limit to the amount of work that the fireman can do, and the great engines in use at present tax even the strongest fireman to the utmost. If the size or speed of locomotives is increased very materially in the future it will be necessary to have two men, instead of one, as firemen, or to use mechanical stokers, or to find some other kind of fuel. In point of fact the mechanical stoker has been recently tried with success, and this will probably help in solving the problem. But there is also the strong probability that the use of liquid fuel will become more and more popular. At the present time many locomotives in the West and Southwest, as well as in Europe and in Asia, have been equipped with burners for the consumption of crude petroleum. No modification in the construction of the locomotive is required for this change of fuel except some slight alteration in the arrangement of the brickwork of the fire-box, and the introduction of the burners. These, however, are simple arrangements that throw into the fire-box, a spray of steam and vaporized oil, which burns freely and generates an intense and steady heat. With this kind of fuel the fireman need not be considered, as the largest engine thus equipped may be "fired" with far less labor than is required on the smallest coal-burning, narrow-gauge locomotive.

THE WESTINGHOUSE AIR BRAKE

The application of steam as a motive power for running trains of cars solved one great problem; but it created another. The second one was the problem of how to stop the trains once they had started. On short trains made up of the light cars used at first, the hand brakes were sufficiently effective for practical purposes. But as trains were increased in length and weight and were run at high speeds, it became imperative to find some means of stopping such trains quickly and with certainty.

With a hand brake working on each pair of trucks, as on passenger coaches, it was possible to make reasonably quick stops when there were enough members of the train crew to work all the brakes simultaneously. But in practice it was found impossible to maintain this ideal condition. For emergency stops the brakemen were summoned by signals of the whistle given by the engineer, and there was necessarily some little interval of time after this signal before the most alert crew could begin the relatively slow process of applying the brakes.

The engineer himself could give valuable aid in stopping the train by reversing his engine, the locomotive acting as a brake to check the oncoming cars. But this check acted only at the forward part of the train, and being applied suddenly, caused the rear cars to rush against the forward cars with terrific force, sometimes driving in the bumpers and wrecking the train. Obviously an ideal system of brakes must be one that acted upon all the cars of the train simultaneously and under control of the engineer; and presently such a system was invented by Mr. George Westinghouse.

Other inventors had tried to produce a practical system of brakes, such as those using steam as a working force, or systems of hand-wound springs; but Mr. Westinghouse utilized compressed air, and from the first his brakes proved effective.

His first air brake, operated successfully in 1869, was the "straight air brake" type—one that has now been replaced almost universally by the automatic. In this brake system there was an air reservoir on the locomotive, and steam was used for making the compression. From this reservoir a line of gas pipe ran through the cab of the engine beneath the tender and under each car, the space between the cars being bridged by rubber tubes and easily-adjusted couplings. This line of pipe, called the train pipe, was connected near the centre of each car with a cylinder which contained a piston with a stem which acted upon the brake shoes by means of a series of levers and connecting rods.

In the cab, placed conveniently for the engineer, was a valve by means of which he could cause the compressed air to flow into the train pipe and thus act upon the brake cylinders of the cars. This could be done gradually for making a slow stop, or with full force as the case required, and the brakes could be released by turning the valve to a point which opened a vent and allowed the air to escape.

The effect of this invention was revolutionary. Stopping the train was no longer dependent upon manual labor applied intermittently at different points, but was placed entirely in the hands of the engineer who applied the required power almost simultaneously at all points along his line of cars. Thus the brakeman was relieved of one of his perilous tasks, which on freight trains took a heavy toll in loss of lives.

This relatively simple, and usually effective, system had two grave defects. The first of these lay in the fact that if there was a leak—even a very small one—anywhere along the line of the train pipe or the brake cylinders, the brakes would not work, the compressed air being exhausted into the atmosphere instead of acting on the brake cylinders. The common accident of having his train "break in two" rendered the engineer powerless to stop the cars, and disastrous "runaways" sometimes resulted. The second defect, which became more and more apparent as the length of trains was increased, was the impossibility of applying the air to the brakes of the rear cars as quickly as to those near the engine, since the compressed air could not travel the length of the train pipe instantaneously, on account of the frictional resistance.

These defects were quickly recognized by Mr. Westinghouse, and in 1876, seven years after he applied his first invention, he produced his automatic air brake which overcame them effectually. In this brake the train pipe and the air reservoir were retained as in the straight air brake system, but in addition each car was equipped with a storage reservoir of sufficient size to supply the brake cylinder. In place of the older arrangement in which the train pipe simply retained air at atmospheric pressure when not in use, the new system kept the air in the train pipe under a considerable pressure at all times when the brake was not in use. And, reversing the conditions of the straight air brake, the engineer in order to apply the brakes let out the air in the train pipe instead of forcing air into it, a "triple valve" on each car performing the work of operating the brake cylinder automatically.

The advantage of this system over the older one is obvious. Whereas the detachment of a portion of the train, or a leak in any part of the air brake system heretofore had left the engineer helpless, exactly the reverse condition was produced in the new system. Any leakage of air, either from a break or a defect, caused every brake on the entire train to be applied to the wheels and brought the train to a stop. Moreover, with the new system it was now possible to equip each car with a valve which would lessen the pressure of air in the train pipe so that the train could be brought to a stop by the trainmen in the rear or intermediate coaches as readily as by the engineer.

This system worked perfectly on passenger trains; but on long freight trains the resistance to the passage of the escaping air through the train tube was so great that if an emergency required the full force of the brake to be applied suddenly, the brakes of the rear cars did not come into use until several seconds after those of the forward cars. The result was that the momentum of the rear cars caused them to strike the forward cars with great violence. But Mr. Westinghouse overcame this defect by an ingenious use of the triple valve mechanism of each car, whereby the application of the emergency brake by the engineer caused the air in the train pipe on each car to be discharged simultaneously into the brake cylinder. In this manner the discharge of air not only allowed the brakes to act, but assisted them in doing so. This was only the case, however, when the emergency application of the brake was made, this system of venting on each car into the brake cylinder not being brought into play when ordinary stops were made. Thus the engineer in this quick-action automatic air brake has really two brakes at his command, one for making ordinary stops, the other for emergencies.

In 1891 a so-called high-speed air brake was perfected, this brake being really a modified quick-action automatic brake. This modification consists of the addition of an automatic pressure-reducing valve connected with each brake cylinder. In the high-speed air brake as applied when the train is running rapidly, the highest possible pressure is applied at once to the wheels, but this pressure is lessened by the automatic pressure-reducing valves as the speed diminishes. This method of applying the brakes is the most effective way of getting the full benefit of their stopping power. This high-speed brake, therefore, represents the highest perfection in train-stopping devices.

We have referred here specifically to the air brake as used on steam railroads. In another chapter the subject has been touched upon in connection with electric railroads. In such brakes the compression of the air is accomplished by electricity instead of steam, but the general principles involved are the same as those just described.

It should not be understood that the Westinghouse air brake was the only one, or the only type of brake, devised and brought to practical perfection. For a time a vacuum brake, which utilized atmospheric pressure, offered keen rivalry. But eventually the type of brake perfected by Mr. Westinghouse, modified in certain details in the various countries of Europe and America, gained precedence, which it still retains.

AUTOMATIC COUPLINGS

The perfection of the air brake removed one great source of danger that menaced the crews of freight trains. There still remained another almost as great, particularly in the matter of maiming its victims, when not actually killing them. This was the old method of coupling freight cars as practiced in America. There were few old-time trainmen, indeed, who could show a complete set of full length digits, the buffers of the old-fashioned couplings being responsible for the lost and shortened members.

The freight brakeman has to make scores of couplings on every trip. And he literally took his life in his hands upon each and every occasion of making a coupling by the old method.

This old form of couplings consisted of two buffers—one on each car—joined together by an iron link about fifteen inches long, a movable pin inserted at either end holding the link in place and thus joining the cars. When a coupling was to be made the brakeman raised the pin in the buffer of the stationary car and tilted it at an angle in the pin-hole at the top of the buffer so that, while it remained raised, the jar of the striking buffers at the moment of coupling caused it to fall into place and complete the coupling. The link was left hanging in the moving car which was being shunted in to be coupled; but in this position the projecting end was so low that it would miss the hole in the opposite buffer, and thus fail to make the coupling, unless raised and inserted just at the moment before the buffers came together.

This raising and inserting of the link was the dangerous part of making a coupling. It could only be done by the brakeman while standing between the cars. And he must raise the link, insert it, and remove his hand in a fraction of a second if the car was moving at a fair rate of speed, otherwise his fingers or hand would be caught between the buffers and crushed. And a crushed hand or arm meant subsequent amputation, for the force of the collision between the buffers crushed the bones beyond repair.

There was a way in which the coupling could be made whereby the hand was not endangered. This was by using a stick for raising and guiding the link into the buffer. Some railroads at first furnished sticks for this purpose. But no brakeman would stoop to use them. Had he done so he would have been hooted and jeered off the road by his train mates. And so his pride made him risk his limbs and his life, and fostered the recklessness of the old-time brakeman.

But in 1879 Mr. Eli Janney, of Pittsburg, patented an automatic car-coupler that was both simple and effective; and in 1887 the Master Car Builders' Association accepted this type of coupler. A little later the U. S. Government, influenced by the appalling loss of life among the brakemen, passed laws compelling all cars to be equipped with some form of automatic coupling device, and naturally the Janney coupling was the one adopted. In using this coupling the brakeman did not have to step into the dangerous position between the cars, either for making the coupling, or disconnecting the car. The act of coupling was done automatically, while the uncoupling was effected by the use of a lever operated from the side of the car.

A somewhat technical description of this coupling is as follows:

"The Janney coupling consists of a steel jaw fitted on one side with a knuckle or L-shaped lever turning on a vertical pin; this knuckle when being swung inward lifts a locking pin which subsequently drops and so prevents the return of the knuckle. An identical coupler is fitted to the end of the adjacent vehicle, and, so long as both or either of the knuckles are open when the vehicles come into contact, coupling will be effected; to uncouple, it is only necessary to raise either of the locking pins, by means of a chain or lever at the side of the vehicle. The knuckles have each a hole in them to permit of the use of the old link and pin coupler, when such a fitting is met with. At first, this coupling gave some trouble through the locking pins occasionally creeping upward, but in the larger model, which represents the later form, there is an automatic locking pawl that prevents this motion; owing, however, to the pawl being attached to the lifting shackle, it in no way interferes with the pin being raised when disconnecting."

Even before the invention of the Janney coupling a semi-automatic coupling device had been used extensively on passenger cars. But this device which in effect was that of two crooked fingers hooked together, allowed the ends of the coaches to swing and roll in a manner most disagreeable to many passengers. The Janney couplings corrected this, since these couplings in their improved form hold the ends of the cars as in a vice.

A COMPARISON—THE OLD AND THE NEW

Stephenson's locomotive and its tender, when loaded to full capacity with fuel and water, weighed seven and three-quarter tons. The locomotive itself was a trifle over seven feet long. In 1909 the Southern Pacific Railway purchased a Mallet Compound locomotive which, with its tender, weighs three hundred tons, or approximately forty times the weight of the little Rocket. This great locomotive is over sixty-seven feet long, or some nine times the length of the Rocket, and will haul more than twelve hundred tons back of the tender.

The cylinders of the Rocket were eight inches in diameter, with a seventeen inch stroke; the high-pressure cylinders of this Mallet locomotive are twenty-six inches in diameter, and the low-pressure cylinders are forty inches. But curiously enough the driving wheels of the two engines show little discrepancy, those of the Rocket being fifty-six inches in diameter, as against fifty-seven for those of the larger engine. The total heating surface of the Rocket was one hundred and thirty-eight square feet, that of the new locomotive 6,393 square feet. To heat this great surface oil is used for fuel, so that the task for the fireman is lighter than on many locomotives less than one-half the size.

On this locomotive there are two sets of cylinders driving two sets of driving wheels on each side, making a total of sixteen drivers in all. From the size of these drivers it is evident that the engine is designed for strength rather than speed, although of course relatively high speed can be attained if desired. On the section of road over which it operates there is a maximum grade of one hundred and sixteen feet per mile, and it was for negotiating such grades with full loads that the locomotive was designed.

V
FROM CART TO AUTOMOBILE

THE use of the wheel as a means of reducing friction dates from prehistoric times. The introduction of this device must have marked a veritable revolution in transportation, but unfortunately we have no means of knowing in what age or country the innovation was effected. We only know that the Chinese have used wheelbarrows and carts from time immemorial, and that sundry very ancient pictures and sculptures of the Egyptians and Babylonians prove that these peoples were entirely familiar with wheeled vehicles.

The earliest form of wheel was doubtless a solid disk, and such a wheel is still in use in many places in the East; but the wheels of the Assyrian chariot were spoked after the modern fashion, and provided with rims of metal. The introduction of the wagon spring, however, was a comparatively modern innovation. The use of springs very considerably reduces the resistance, thus adding to the efficiency of wheeled vehicles; but the reduction is not very obvious unless the roads are tolerably good, nor is it probable that the ancient nations could readily have measured the effect even had the idea of springs suggested itself.

As regards good roads, these are, to be sure, no modern invention, since the Romans had carried the art of road-building to a very high degree of perfection. The integrity of the Roman Empire depended very largely upon the highways that linked all parts of its circumference with the Imperial centre; and in a perfectly literal sense all its roads led to Rome. The Roman roadbed was constructed of several layers of stone, and it was one of the most resistant and permanent structures ever devised. As late as the sixteenth century of our era there were no roads worthy of the name in England except the remains of those constructed many centuries before by the Roman occupants. It was not until well toward the close of the eighteenth century that Macadam and Telford devised methods of road-making whereby broken stone and gravel, pounded to form a smooth surface, gave the modern world roadbeds that were in any way comparable to those early ones of the Romans.

This development of road-building corresponded, naturally enough, with an advance in the art of carriage building, and the increased popularity of stage coaches. We are told that about 1650 the average rate of speed of the stage wagons in England was only four miles an hour; whereas the stage coaches moved over the improved roadbeds of the nineteenth century at an average speed of about eight miles an hour, which was sometimes increased to eleven miles. After about the year 1836, however, the stage coach was rapidly displaced by the steam railway, and the interest in roadbeds somewhat abated until brought again prominently to public attention by the users of bicycles and automobiles.

THE DEVELOPMENT OF THE BICYCLE

It is rather surprising to learn that in point of time the automobile antedates the bicycle. Yet such, as we shall see in a moment, is the fact. Every one is aware, however, that the bicycle came into popularity at a time when the very existence of the automobile had been practically forgotten, and that subsequently it lost its popularity almost over night when the automobile came to its own. Viewing the subject retrospectively, perhaps the most singular thing is that both vehicles were so long delayed in making their way to public favor. There were, however, sundry very practical obstacles placed in the way of the larger vehicle; and the bicycle was not at first a device calculated to prove attractive to the average wayfarer.

The very earliest bicycle appears to have been the so-called hobby horse or dandy horse introduced about the year 1818 by Baron von Drais in France. It was a primitive vehicle, the user of which half rode and half ran, propulsion being effected simply by thrusting the feet against the ground. In effect the rider of the hobby horse ran with a stride greatly lengthened through the partial support afforded by the saddle, and with correspondingly increased speed. He could, of course, on occasion coast down hill or on a level surface when considerable momentum had been acquired, and supports for his feet were provided to facilitate this end. At first the machine promised to become popular, but it was soon ridiculed out of court.

Something like twenty years later—that is to say about the year 1840—a treadle-bicycle was invented by Kirkpatrick MacMillan, an English blacksmith. The machine did not become popular, however, and it was not until simple cranks were fitted to the front wheel of the bicycle that this form of vehicle came into anything like general use. This very simple expedient was first suggested, seemingly, by Pierre Lallament, a Frenchman, in 1866. His machine came to be known in England as the bone shaker, and doubtless it deserved its name, for as yet neither the wire suspension wheel nor the rubber tire had been invented. Both these improvements were quickly introduced, however; the suspension wheel by Mr. E. A. Cowper, in 1868. The first rubber tires, used about 1870, were solid, and it was not until 1888 that the Irishman, Mr. J. B. Dunlap, introduced the pneumatic tire. Meantime the geared bicycle, with which every one is nowadays familiar, had been introduced in 1879 by Mr. H. J. Lawson and brought to the familiar form of the "safety" in 1885 by Mr. Starley. The combination of low wheels geared to any desired speed with pneumatic tires was the finishing stroke.

The problem of making the bicycle a relatively speedy vehicle had indeed been solved by the use of a large wheel—sometimes sixty inches in diameter—operated by a simple crank after the manner of the early machine of Lallament; but while bicycles of this type attained a considerable measure of popularity, the danger of taking a "header" on encountering any obstacle in the road was one that seemed to the average person to out-measure the pleasure or benefit to be derived from rapid transit thus attained. The safety bicycle, however, practically eliminated this danger. It was, moreover, comparatively easy to balance; and not long after its introduction in perfected form, with pneumatic tires, it had made an appeal to which all the world responded. For a few years the safety bicycle was the most conspicuous of vehicles on every country road, and partisans of outdoor life believed that the health and stamina of the generation were to be increased immensely by the new vehicle.

Nor were these anticipations altogether visionary, as undoubtedly the bicycle did do much to improve the average health of nearly all classes of citizens. But its popularity was too suddenly acquired to be permanent, and at the very moment when it was most used, another vehicle was suddenly developed which was to lead to its practical abandonment by the great mass of people for whom it might have been supposed to afford a means of permanent recreation.