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diff --git a/old/51242.txt b/old/51242.txt deleted file mode 100644 index df27b4a..0000000 --- a/old/51242.txt +++ /dev/null @@ -1,3705 +0,0 @@ -Project Gutenberg's Electricity in Locomotion, by Adam Gowens Whyte - -This eBook is for the use of anyone anywhere at no cost and with -almost no restrictions whatsoever. You may copy it, give it away or -re-use it under the terms of the Project Gutenberg License included -with this eBook or online at www.gutenberg.org/license - - -Title: Electricity in Locomotion - An Account of its Mechanism, its Achievements, and its Prospects - -Author: Adam Gowens Whyte - -Release Date: February 17, 2016 [EBook #51242] - -Language: English - -Character set encoding: ASCII - -*** START OF THIS PROJECT GUTENBERG EBOOK ELECTRICITY IN LOCOMOTION *** - - - - -Produced by WebRover, Chris Curnow, Haragos Pal and the -Online Distributed Proofreading Team at http://www.pgdp.net -(This file was produced from images generously made -available by The Internet Archive) - - - - - - - - - - The Cambridge Manuals of Science and - Literature - - - ELECTRICITY IN LOCOMOTION - - - - - - - CAMBRIDGE UNIVERSITY PRESS - London: FETTER LANE, E.C. - C. F. CLAY, MANAGER - - [Illustration] - - Edinburgh: 100, PRINCES STREET - London: H. K. LEWIS, 136, GOWER STREET, W.C. - Berlin: A. ASHER AND CO. - Leipzig: F. A. BROCKHAUS - New York: G. P. PUTNAM'S SONS - Bombay and Calcutta: MACMILLAN AND CO., LTD. - - - _All rights reserved_ - - - - - - - - ELECTRICITY IN - LOCOMOTION - - AN ACCOUNT OF - ITS MECHANISM, - ITS ACHIEVEMENTS, AND - ITS PROSPECTS - - BY - - ADAM GOWANS WHYTE, B.Sc. - - Editor of _Electrical Industries_ - and _Electrics_ - - - Cambridge: - at the University Press - 1911 - - - - - - TO - EMILE GARCKE - - -_With the exception of the coat of arms at the foot, the design on -the title page is a reproduction of one used by the earliest known -Cambridge printer, John Siberch, 1521._ - - - - - PREFACE - - -In the following pages an attempt is made to give a clear picture of -the part which electricity has taken and will continue to take in the -development of locomotion. - -Some of the aspects of electric traction are highly technical; others -are purely financial. It is impossible to understand the achievements -and possibilities of electricity in locomotion without a certain amount -of discussion of both these points of view; but it is not necessary to -go deeply into either in order to catch some of the enthusiasm which -inspires the electrical engineer in his efforts to extend electric -traction everywhere on road and rail. The hopes of electrical conquest -extend, indeed, to locomotion on the sea and in the air as well as on -the land. At the root of these hopes there lies a firm faith in the -superior economies and flexibility of electricity as a mode of motion. - -In the explanations which are given of electric tramways, electric -railways, electric automobiles, electric propulsion on ships, and the -other phases of electric traction, nothing but the most elementary -knowledge of electricity is presupposed. A certain amount of technical -description is unavoidable, but I have restricted it as far as possible -to essential matters which throw light upon the meaning of the various -systems of electric traction and explain the economic and physical -reasons for their adoption. - -Anyone who glances over the history of electric traction will be struck -by the absence of outstanding names. There is no man who occupies the -same position in the sphere of electric locomotion as Watt does in the -world of steam, or Stephenson in the world of railways. As a pioneer, -Dr. Wernher von Siemens perhaps deserves more honour than any other. -But the leading ideas embodied in electric traction systems were -contributed by engineers who worked in the general field of electrical -engineering; and they have been applied and developed by a numerous -band of men who have added one brick of experience and ingenuity to -another until the imposing structure was made visible to the world. - -Nevertheless, I hope the story as told briefly in the following -chapters will not be found devoid of human interest. It has the -advantage, at any rate, of the attraction which anything pertaining -to electricity holds for all sections of the public. This attraction -deepens upon closer acquaintance with the mechanism and the history of -electricity in action; and if any of the descriptions and forecasts are -found to be prejudiced in favour of a single instrument of locomotion, -the fault may be considered to rest with the spell which electricity -throws upon everyone who is concerned in any way with its applications -in the service of man. - -I have to acknowledge the kind assistance of Mr. Frank Broadbent, -M.I.E.E., in looking over the proofs of this volume. - - A. G. W. - - _21 April 1911_ - - - - - CONTENTS - - - PAGE - - PREFACE vi - - CHAP. - - I. The Wheel and the Public 1 - - II. Early Tramroads and Railways 4 - - III. The Birth of Electric Traction 12 - - IV. The Essential Advantages of Electric Traction on - Tramways 19 - - V. The Mechanism of an Electric Tramcar: the Overhead - System 29 - - VI. Conduit and Surface-Contact Tramway Systems 37 - - VII. The Backwardness of Electric Traction in Great Britain 46 - - VIII. Electric Tramway Stagnation. The Trolley Omnibus 55 - - IX. Regenerative Control 67 - - X. Accumulator Electric Traction. The Electric Automobile 70 - - XI. Petrol-Electric Vehicles and main Marine Propulsion by - Electricity 82 - - XII. The Pioneer Electric Railways 92 - - XIII. Electric Railways from the Engineering Point of View 107 - - XIV. Electric Traction on Main Line Railways 116 - - XV. Curiosities of Electric Traction 124 - - XVI. The Future 138 - - INDEX 142 - - - - - CHAPTER I - - THE WHEEL AND THE PUBLIC - - -One of the greatest of unknown men of genius was the inventor of the -wheel. Probably--as in the case of most inventions--he shares the -credit with others who prepared the way for him by discovering that -heavy weights could be more easily rolled than dragged. But, whatever -the origin of the wheel and axle, the combination was so admirable that -it remained unchanged in its essential features for centuries and still -forms the primary element in locomotion. - -Some of the earliest forms of vehicle can be found co-existing with -the very latest. In Oporto, for instance, there are electric tramways, -but there are also ox wagons which seem to belong to the childhood of -the world. The wheels are rigidly fixed to rotating axles (the oldest -known arrangement) and the supports of both the front and the back -axles are rigidly fixed to the wagon. The result is that the vehicle -cannot 'steer' and must be dragged round corners. Some time ago the -authorities, realising at last that this dragging was ruinous to the -road surfaces, made a regulation that all wagons should have their -front axles pivoted. This attempt at improvement caused more agitation -than the Revolution itself. The owners of wagons argued--with perfect -justice--that the rigid wagon had served for innumerable generations; -and they refused, in the face of fines, to make the change. Their -resistance was so general and so dogged that the law became a dead -letter, and the people reverted with great content to the ancient -system which divided the business of local transport between yoked oxen -and women who had been trained from girlhood to carry heavy loads upon -their heads. - -This example of conservatism, though extreme, is characteristic of -the attitude of the general public towards innovations in locomotion. -Until mechanical power came to be used, there was--for many -centuries--nothing which could be described as a radical innovation in -transport. Roads were multiplied and improved; some advance was made -in the design and construction of carriages; and the organisation of -posting and stage-coach services was developed. But little more was -done. Compared with these superficial changes, the idea of using steam -power on the highway or on a railroad was so drastic a change that -it roused tremendous opposition. The railway companies fought this -opposition and overcame it, but the use of steam carriages on ordinary -roads was postponed until the appearance of the petrol motor encouraged -a movement--once more against strong prejudice--for the repeal of the -legislation which restricted the use of mechanically-propelled vehicles -on the roads. In a similar way horse tramways were violently attacked; -and their conversion to electric traction was opposed by a determined -minority in every town. More recently, there was a vigorous agitation -against the substitution of motor omnibuses for horse omnibuses in -London and elsewhere. - -To some extent this recurrent opposition was reasonable enough. The -new forms of locomotion had dangers of their own; they were generally -noisy and sometimes dirty; and occasionally, as in the case of early -tramways, they were a nuisance to existing traffic. But it may be noted -that electricity claims to provide a means of locomotion not only more -rapid and more efficient (in most cases) than any other, but free from -many of the drawbacks which gave conservatism an excuse for opposing -the introduction of steam and other forms of locomotion. - -In the following pages I hope to give a clear account of the -achievements of electricity in the field of locomotion and also to -indicate some of its more immediate potentialities. - - - - - CHAPTER II - - EARLY TRAMROADS AND RAILWAYS - - -It has sometimes been remarked, by unfriendly critics, that tramways -are an apology for bad roads. That is to say, if road surfaces were -perfect, there would be no need to lay rails in order to allow vehicles -to run easily. - -Although this view of the case may be no better than a quarter-truth, -it is justified to the extent that tramways were, as a matter of fact, -the outcome of an attempt to escape from bad road surfaces. In the -early days of mining, coals were taken by horsedrawn wagons from the -pits to the harbours. The passage and re-passage of heavy vehicles on -the same roadway led to the formation of deep ruts; and the first step -towards both the tramway and the railway was taken when logs of wood or -'trams' were laid in the ruts to facilitate transport. - -The next step was to make the upper surface of the log round and the -rims of the wheels hollow, so that they fitted over the rails and kept -the wagons on the track. Owing to the upper part of the rails wearing -away quickly, thin plates of iron were in some cases nailed to them. -This improvement led to the adoption of a cast-iron rail, fastened to -wooden sleepers. - -The earliest cast-iron railway was laid down before the middle of the -eighteenth century, about one hundred years after the first wooden -'tram-ways.' Half a century later we find the first rail-and-wheel -combination as we know it on modern tramways and railways, where the -wheel carries an inner flange and runs upon the head of a narrow metal -rail. This is the form which experience has proved to be best adapted -for safety, speed, and economy in power. The improvements made since -the beginning of the nineteenth century have been in matters of detail. - -Many miles of colliery tramroads were in existence when--at the -beginning of the nineteenth century--the idea of using the steam engine -in place of the horse was taken up by engineers. They were concerned -at first solely with the carriage of coal; the idea of conveying -passengers arose at a later date, after the steam automobile had -been tried and abandoned for the time being. George Stephenson, for -instance, ran his first locomotives on colliery tramroads; and the -first railway--between Stockton and Darlington--was used for passengers -merely as an afterthought. It was, in fact, designed to be a tramroad -for the use of the public in general transport by horse traction. - -The most curious feature of this stage in the evolution of locomotion -was that, although Stephenson's locomotives had been at work for -several years and although several schemes of iron roads had been -projected, very few people had any conception of the development -awaiting the locomotive and iron road in combination. They did not even -appreciate the proved fact that the locomotive was a more efficient -means of transport than the horse. An immense amount of pioneering work -had to be done before the impression of a new era could be borne in -upon the public mind. These were the days when the _Quarterly Review_ -backed 'old Father Thames against the Woolwich Railway for any sum' and -when a witness before a Parliamentary Committee (on the Liverpool and -Manchester Railway Bill, in 1825) thought himself safe in suggesting -that a steam locomotive could not start against a gale of wind. - -When these prejudices were overcome, many years had to pass before -the objections of landowners and citizens were worn down. Railway -engineers spent most of their time in a form of diplomatic warfare with -opponents to their schemes; huge sums--part of which still lingers in -the capital accounts of railway companies--were spent in Parliamentary -proceedings over Railway Bills. This barren process had to be repeated -when electric traction made its appearance; but happily the electrical -fight was not upon quite so extensive a scale, nor was the period -of preparation followed by anything comparable to the Railway Mania -of 1845, when the public made up for its early contempt of railway -enterprise by tumbling over itself to get shares in some of the most -crazy schemes which were ever put into shape by unscrupulous company -promoters. - -The early history of the steam railway is interesting in connection -with electrical locomotion for two reasons. It shows that the railroad -proper evolved out of the tramroad or 'light railway,' as it would -now be called--a type of line which is specially suited to electrical -operation. It also includes a controversy between three modes of -traction; and this controversy forms a very good introduction to -a discussion of the reasons why electricity is so economical in -locomotion. - -These three modes were (1) stationary engines: (2) locomotives: (3) the -device known as the 'atmospheric railway.' - -In both the first and third, engine houses were placed close to the -line at convenient intervals. In the first, each steam engine operated -an endless rope to which the train of carriages was attached. The -system is still in use for colliery working and is also employed (in -an improved form, of course) for funicular railways. George Stephenson -himself employed it to assist locomotives up heavy gradients. In the -atmospheric railway the stationary engines were used to exhaust the -air from a length of cast-iron piping laid close to the railway. The -principle is the same as that of the 'pneumatic tube' which the Post -Office uses for sending papers over short distances. The papers are -placed in a cylinder which fits the interior of the tube; and when the -air is exhausted from the tube in front of the cylinder, the pressure -of the air behind it drives the cylinder forward. - -Nowadays it is difficult to realise that such a system was seriously -proposed for railway work and actually adopted by an engineer of such -eminence as Brunel. But in point of fact it was recommended by two -Board of Trade experts in 1842 and by a Select Committee appointed in -1845 to consider several Bills for atmospheric railways. It was tried -at Dalkey and Croydon, and it was installed under Brunel's supervision -on a six-mile line in Devon. The carrier in the tube was connected -to the train through a longitudinal slit at the top of the tube. The -slit was closed by a leather flap, except when momentarily lifted by -the passage of the train. A great deal of ingenuity was exhausted in -attempting to make this 'longitudinal valve' efficient, but it was -found that heat, moisture, and frost made the leather deteriorate so -rapidly as to render it hopelessly ineffective in a short time. After a -series of misfortunes the atmospheric railway became a mere curiosity -in the history of invention. - -Stephenson was right in regarding the atmospheric railway as 'only -the fixed engine and ropes over again, in another form.' He was also -right in his belief that the steam locomotive was more economical -than either of its rivals. But the stationary engine idea had the -germ of an even sounder principle than that of the locomotive. Both -in electric tramways and electric railways the power is obtained from -stationary engines. The main difference between the electric system -and the old rope and atmospheric systems lies in the superior economy -with which the power is conveyed electrically to the trains. There are -other important differences; but the essential point is that both rope -traction and pneumatic propulsion wasted so much power between the -engine and the train that their other advantages were annulled, and it -was found cheaper to put the engine on wheels and make it drag itself -as well as the train. - -Brunel's reasons for his faith in the atmospheric railway are well -worth quoting for the light they throw indirectly upon the advantages -of electric traction. He argued that stationary power, if freed from -incumbrances such as the friction and dead weight of a rope, was -superior to locomotive power, on the following grounds: - -(_a_) A given amount of power may be supplied by a stationary engine at -a less cost than if supplied by a locomotive. - -(_b_) The dead weight of a locomotive forms a large proportion of the -whole travelling load, and thus inherently involves a proportionate -waste of power--a waste which is enhanced by the steepness of the -gradients and the speed of the trains. - -Experience has proved the soundness of these principles. There has -been a steady improvement in the power and efficiency of locomotives, -but progress has reached a point at which further increases in speed -and accelerating power (a very important matter) are not attainable -without a prohibitive increase in the consumption of coal and a costly -strengthening of the railway track to stand the strain of heavier -engines pounding along at very high speeds. Electric traction, which is -a reversion in part to the stationary engine system, offers a means of -escape from the limitations of the locomotive. - -There is still some doubt in the minds of railway engineers whether -electric traction is really superior to the steam locomotive on the -main railway lines, where distances are great and train loads heavy. -But the superiority is admitted on suburban lines and also on tramways, -where electricity has almost completely supplanted both horse and steam -traction. If Brunel had foreseen how economical electricity would be in -the transmission of power between engine and train, he would have felt -still more confident in his defence of the stationary engine. - - - - - CHAPTER III - - THE BIRTH OF ELECTRIC TRACTION - - -The story of electric traction really begins in the laboratory -of Faraday. He was the first to produce mechanical rotation by -electrical means; and, although he had no practical end in view, his -investigations produced the germ of the commercial dynamo and thence of -the commercial electric motor. - -That germ, however, took about half a century to develop. It is true -that in 1837 (about ten years after Faraday's discovery) Robert -Davidson experimented with an electric locomotive on the Edinburgh -and Glasgow Railway; it is also true that Jacobi, two years later, -propelled a boat on the Neva with electric power. But these early -attempts were not on a commercial scale. Not only was the motor a -crude contrivance, but the method of producing the electric power was -hopelessly extravagant. - -At that period the 'primary battery'--similar in character to those -still used for laboratory purposes, ringing electric bells, and so -on--was the best available source of electricity. Such batteries -generate current by the chemical consumption of zinc. In order to -obtain sufficient power to move a boat, a large number of batteries had -to be coupled together. They were expensive in first cost, expensive in -the zinc which was their 'fuel'; and they became rapidly exhausted. - - [Illustration: =DYNAMO= =MOTOR= - Fig. 1. Diagram to illustrate the essential identity of the dynamo - and the motor. The dynamo generates electricity when the armature or - group of coils is forcibly revolved close to magnets, thus converting - mechanical energy into electrical energy. The motor causes its - armature to revolve forcibly when current is supplied to it from the - dynamo. Thus the motor converts electrical energy into mechanical - energy.] - -The essential step towards the commercial plane was taken when an -efficient means was devised for transforming mechanical into electrical -energy on a large scale. The first 'dynamo-electric' machines, invented -about the middle of last century, were merely hand machines. Their -power was limited by the strength of the permanent magnets employed in -their construction; and although an increase in power was obtained by -multiplying the number of magnets and driving by steam power, it was -not sufficient for commercial purposes. In 1867 electro-magnets were -first employed by Siemens and Wheatstone; and from this application -there was developed a machine whose power as a generator of electricity -was limited only by its size and the speed at which it was run. - -It is unnecessary for our present purpose to enter into the technical -details of the modern electric generator and the modern electric motor. -The principles underlying them are quite simple, although the theory -of their design and the practice of their construction and operation -are almost a science in themselves. A dynamo or electric generator is a -machine for transforming mechanical into electrical energy; an electric -motor is a machine for transforming electrical energy into mechanical -energy. If, therefore, we place an electric motor upon a vehicle and -supply it continuously with current from a dynamo, the motor will -rotate and can be used to propel the vehicle. That is the essential -mechanism of electric traction. - -The simplicity of the arrangement is enhanced by the fact that the -dynamo and the motor are virtually the same machine. In the dynamo, a -cylindrical 'armature' of coils is forced to rotate close to the poles -of electro-magnets; the energy exerted in turning the armature against -the influence of the electro-magnets is transformed into the energy of -electric currents in the coils of the armature. In the motor, which -also consists of an armature close to the poles of electro-magnets, the -process is reversed. When a current is passed through the coils of the -armature, the reaction between these currents and the electro-magnets -causes the armature to revolve. - -This reversibility of the dynamo was, according to a story frequently -repeated, first discovered quite by accident. In a Paris exhibition a -number of Gramme dynamos--or dynamo-electric machines, as they were -then called--were being separately connected to lamps and other devices -for showing the effect of electric currents; and when one was started -up it was found that another was being _driven_ at a rapid rate. -Investigation showed that the second one had been coupled up to the -first by mistake and was therefore being worked as a motor by it. - -This was in the year 1879; and the story of the incident served to -draw general attention to the discovery of a new and efficient means -of transmitting power. Engineers recognised that in the steam-driven -dynamo they had the means of producing powerful electric currents, -while in the electric motor, connected by wires to the dynamo, they -had the means of reproducing the power in mechanical form at a -distance. There were, of course, losses of energy in the process. -A certain percentage was lost in the dynamo itself, some in the -transmitting wires, and some in the motor. But the all-round efficiency -of the arrangement was much higher than that of any other system of -transmitting power from one point to another several miles distant. - -In order to apply this system to propelling vehicles it was only -necessary to devise a continuous connection between the motor on the -vehicle and the stationary dynamo. This was done on the first electric -railway by means of a 'third rail,' substantially in the same way as -is now familiar on underground and other electric lines. The third -rail was a metal conductor supported on insulators and connected to -the dynamo. The vehicle or car was furnished with a metal brush or -skate which rubbed along the third rail as the car moved forward. The -current thus collected was led through the motor (which drove the axle -of the car through toothed wheels) and thence to the track rails, which -conveyed the current back to the dynamo and so completed the electrical -circuit. Messrs Siemens and Halske exhibited the first electric railway -of this type at the Berlin Industrial Exhibition of 1879. - -Another method of collecting the current was tried soon afterwards -and formed the direct forerunner of the electric tramway on the now -standard 'overhead' system. The disadvantage of the third rail system -is that it involves an exposed 'live' conductor close to the ground. -It is therefore quite unsuited for use on streets. Consequently the -next step towards the electric tramway was to carry the electrical -conductors overhead by supporting them on poles erected at the side of -the track. The first installation of this kind was laid down at the -Paris Exhibition of 1881. In that case the conductor was an iron tube -with a slot along its lower side; and inside the tube was a 'boat' -which slid along and was connected to the car by means of a flexible -wire. A second tube, also with a boat and connecting wire, was provided -to carry the return current. We shall see later how this arrangement -evolved into the familiar 'trolley' system. - -The mention of a slotted tube recalls the atmospheric system and, -in so doing, emphasises the superiority of the electric system in -simplicity, flexibility, reliability, and economy. Brunel's faith in -the advantages of stationary engines and the transmission of power -therefrom to moving trains would have been justified by the event if -the pneumatic system of power transmission had been as practicable as -the electric system. But there is an obvious contrast between the huge -pipe of the atmospheric railway, with its impossible 'longitudinal -valve,' and the small tube of the first overhead electric line or the -third rail of the first electric railway. There is also a pathetic -contrast between the prolonged struggles which Brunel and the inventors -of the atmospheric system underwent before they were forced to -acknowledge failure, and the rapid ease with which electric traction -entered into its kingdom when the commercial dynamo and motor were -first produced. The intrinsic difficulties which electric traction -engineers had to meet were not serious. Designers passed, step by -step, from the model electric railway at the Berlin Exhibition to -public lines on a larger scale, and from the model electric overhead -tramway to the 'street railway' or tramway which gradually supplanted -the horse tramway. Each step consisted in an extension of the distance -covered and an increase in the power required, coincident with a -gradual improvement in the details of motors, dynamos, and transmission -equipment. - - - - - CHAPTER IV - - THE ESSENTIAL ADVANTAGES OF ELECTRIC TRACTION ON TRAMWAYS - - -A railway journal once committed itself to the statement that horse -traction was superior to electric traction on roads because the horse -possessed the 'vital principle' of energy in its constitution. - -It is distinctly curious to find an authority on locomotion describing -the essential drawback of horse traction as its distinguishing -advantage. The 'vital principle,' unfortunately, needs food and rest -to maintain it not only during working hours but during the hours of -inactivity as well. In actual practice four horses out of every five in -a tramway stud are in the stables while the fifth is at work. Moreover, -the same stud has to be kept up, at a practically uniform cost, whether -the daily traffic be light or heavy. Thirdly, the 'vital principle' has -only a limited number of years during which--apart from sickness and -disease--it is effective for traction purposes. - - [Illustration: Fig. 2. A typical electric tramway on the overhead - system.--The trolley standard carries the wires for supplying current - to the cars on both the up and down tracks. The driver has his left - hand on the controller handle and his right hand on the brake handle. - (Photograph reproduced by courtesy of Dick, Kerr and Company, - Limited.)] - -Another disadvantage is that the pull which a horse can actually -exercise on a car is strictly limited and is only a small fraction of -the total power represented by the fodder which the horse consumes. -The strain upon a horse in starting a car or omnibus is so great that -a 'lover of animals' used to supply London omnibuses with appeals to -passengers not to stop the omnibus more often than was necessary, -especially on an incline. This was a recognition of the fact that the -horse cannot cope easily with the heavy strain at starting, and that he -requires assistance on heavy gradients. - -It was not surprising, therefore, that on horse tramway systems -the speed was low, the cars of limited capacity, and the fares -comparatively high. The shortness of the journey which a tramway horse -was able to cover without fatigue also tended to limit the length of -routes. - -On all these points electric traction was soon found to be distinctly -superior to horse traction. It was more economical in power; it was -able to maintain higher speeds with larger and more commodious cars; -and there was no narrow limit to the length of routes or the gradients -which could be surmounted. Consequently electric traction offered the -public an improved service at lower fares. - -The whole of the power-producing plant for a typical electric -tramway system is concentrated at a generating station placed (if -possible) near the centre of the system. From this station runs a -network of electric mains to feed the lines with current at convenient -points. This concentration is a benefit on several grounds. A large -generating equipment is cheaper in first cost than a multitude of small -power-producing plants, and it is much more economical in operation. -If every car had its own power equipment, that equipment would need to -be powerful enough to haul itself and the loaded car up the steepest -gradient on the route. That is to say, the sum of the car capacities -would be equal to the sum of the maximum demands. But when the power -is obtained from a single stationary source we do away with the dead -weight of the power equipment on the car, and secure the very vital -advantage that the capacity of the stationary source need not be so -great as the sum of the maximum demands. In actual working it never -happens that all the cars are full of passengers and ascending the -steepest gradients simultaneously. While some are running up-hill, -others are going down-hill; while some are full, others are half full -or almost empty. The result is that the total demand for power at any -time is always very much less than the total of the maximum demands -made by each car; and the capacity of the generating station need be -sufficient to cope only with the smaller amount. - -This advantage reduces the expenditure necessary upon boilers, -engines, and dynamos at the tramway generating station. And it is -enhanced by two valuable capabilities of the electric motor. The first -is its power of taking a heavy overload for a limited period without -injury. There is no difficulty about making an electric motor, whose -normal capacity is 20 horse power, give 40 horse power momentarily, 30 -horse power for several minutes, and 25 horse power during the best -part of an hour. Applied to tramway work, this advantage means that the -rated capacity of the motor equipment of a car may be less than what -is required to haul a loaded car at an adequate speed up the steepest -gradient on the system. Such maximum demands, which only occur at -intervals with each car, can be met by the readiness of the electric -motor for overwork. The motors may therefore be reduced in size, saving -money in first cost and in the current consumed. - -The second valuable peculiarity of the electric motor is that it gives -its 'maximum torque' at starting. That is to say, it exercises the -highest propulsive effort at the precise moment when it is required. -When horses are employed, they have to endure an abnormal strain in -overcoming the inertia of a stationary vehicle; everyone must have -noticed how horses have to struggle to start a car which they can keep -going at an easy trot once it has got up speed. The electric motor--to -use an apparent paradox--gives this abnormal pull as part of its normal -action. As the inertia of the car is gradually overcome, the speed of -rotation of the motor increases and its torque decreases, automatically -and precisely in accordance with the demands of the case. - -The starting torque of a motor is such an emphatic phenomenon that -the driver of an electric car may, if he is careless and switches the -current on too suddenly, jerk any standing passenger off his feet, even -though the total weight of the car may be ten tons or more. Properly -employed, however, the electric motor gives an even and _rapid_ -acceleration. - -This is a far more important point in tramway economics than it -appears to be at first sight. The superiority of the electric tramway -over the horse tramway depends less upon higher speed than upon the -fact that less time is wasted in stopping to pick up and set down -passengers. Time is the vital element in all transport, and it is -especially vital in connection with tramways, which have to stop -with great frequency. If the time which elapses between putting on -the brakes at each stop and getting up to full speed again can be -materially shortened, then the average speed of the tramway journey can -be materially raised. It is easy, by means of powerful brakes, to bring -a car to rest quickly; the electric motor enables speed to be regained -quickly. In this way a high average speed may be maintained in spite of -numerous stops; and, with larger cars, the electric tramway is able to -handle a larger volume of traffic in a shorter space of time than the -horse tramway. - -The time lost in stopping is of so much consequence that, when electric -tramways were introduced, the old custom of stopping the cars at -any desired point was abandoned. Stopping places were arranged at -convenient points along the route, some of them being regular stops -and others optional at a signal from passengers desiring to alight or -to board the car. The public soon got used to walking a short distance -to a stopping place, although they did not, perhaps, appreciate how -much the collection of traffic at a reduced number of points tended to -improve the general tramway service. - -A high average speed with numerous stops was, however, only one of -the improvements which the public derived from electric traction. -Tramway passengers expect to find a car not only at a convenient point -but within a convenient period of waiting. With electric traction -the service became much more frequent than with horse traction. It -is quite possible to run a horse tramway service profitably with -cars at intervals of fifteen to thirty minutes, if the passengers -are patient enough to wait and fill each vehicle. But with electric -traction the main item is the cost of the standing equipment--the -power house, mains, and overhead lines--and unless that equipment is -adequately utilised the revenue will not cover the standing charges. -A fifteen-minute service is, generally speaking, the lowest economic -limit on an electric tramway. Every tramway manager tries to attract -sufficient passengers for a more frequent service; and, as a matter -of fact, it was found that where there was sufficient population the -provision of a frequent and rapid service encouraged tramway travelling -so much that cars had to be run at far shorter intervals than had been -customary on horse tramways. - -The increase of traffic brought with it the demand for larger as well -as speedier cars with a shorter 'headway' or interval between one car -and another. The capacity of a horse car is limited by the fact that it -is not convenient to harness more than two horses to a single vehicle. -But with electric cars there is no extraneous limitation to carrying -capacity. Large double-decked cars with seats for seventy passengers -are now quite common. In America it is a frequent practice to attach -'trailers' to the cars, making a short tramway train. Experiments have -recently been arranged on similar lines in London, for the handling of -the heavy traffic at rush hours. These instances show that electric -tramway capacity is flexible and may be adjusted to the density and the -fluctuating character of the demand. - -Finally, it falls to be noted that the power consumed by a tramcar -is, roughly, proportional to the useful work which the car performs. -As already mentioned, it costs about as much to work a horse tramway -when the cars are empty as when they are full, since the main item is -the maintenance of the 'vital principle' of a certain number of horses -independently of the traffic. But with electric traction the motors -require less power when the cars are running light. And less current -for the motors means less current generated at the power station--that -is to say, less steam, less oil, less coal, less wear and tear. If more -current is demanded, it is because more passengers are being carried -and more revenue earned. - -Reviewing the subject broadly, it is apparent that the adoption of -electric traction on a tramway is not so much a step in advance as -a beneficent revolution. The higher speeds with more frequent, more -comfortable, and more commodious cars have created a volume of traffic -far beyond what could have been handled with horse traction. The change -also led to a great increase in the length of tramway routes and to -the construction of new tramway systems. In 1898, when the electric -tramway movement began in earnest, there were 1064 miles of tramway in -the United Kingdom. Now there are 2562 miles, and the number of tramway -passengers is more than double the total of third class passengers on -the whole system of British railways. The number of tramway passengers -carried during 1909-10 (the last period covered by the published -official returns) was equal to about 62 times the estimated population -of the United Kingdom. - -While the traffic has multiplied in this remarkable fashion, there -has been a heavy reduction in the fares charged. This has been made -possible by the economical features of electric traction. In the -old days a horse tramway had to spend about L80 to earn L100; an -electric tramway need spend only about L60. With this reduction in -the proportion of expenses to receipts, and with the greater volume -of business, it became feasible to stimulate traffic still further -by giving passengers much longer distances for their money. In fact, -electric traction proved so economical that people began to imagine -that there was no limit to the reductions which might be made with -financial safety. However, there is plenty of evidence that a limit -exists. In many cases it has been touched, if not passed, but the -public continues to clamour for all sorts of concessions. These demands -are a great compliment to electric traction, but they are a decided -embarrassment to the tramway manager who believes in a reasonable -margin between his total expenses and his total revenue. - - - - - CHAPTER V - - THE MECHANISM OF AN ELECTRIC TRAMCAR: THE OVERHEAD SYSTEM - - -A rough idea has already been given of the elementary mechanism of -electric traction--the combination of generating station, of cars -fitted with electric motors, and of a sliding contact between the two. -It is in connection with the sliding contact that the ingenuity of -tramway engineers has been mainly exercised. Three distinct solutions -were evolved for tramway work, giving rise to three systems--(1) -the overhead or trolley system; (2) the conduit system; and (3) the -surface-contact system. - -The first system is now almost universal in the United Kingdom. -Part of the London system is equipped on the conduit system; and -the tramways at Lincoln and Wolverhampton are constructed on the -surface-contact system. Beyond these cases the trolley holds the field. -In the United States and on the Continent there is a larger proportion -of conduit work, but from a practical point of view it would hardly -be necessary to mention either conduit or surface-contact if it were -not for the great engineering interest which they possess and for the -controversies to which they have given rise. - - [Illustration: Fig. 3. Diagrammatic illustration of the general - arrangement of an electric tramway on the overhead system. At the - foot is shown the generating station which supplies alternating - current at high-pressure (for economy in transmission) to a - sub-station where it is 'transformed' to low pressure and 'converted' - in a motor-generator to continuous current for distribution to the - trolley wire from which each car takes its current. The course of - the current through the trolley pole and controller and thence to - the motors and back by the rails is indicated by arrows.] - -The overhead system has conquered because it is cheapest in first cost, -cheapest to maintain, most economical in current, and most reliable in -action. Later developments in surface-contact traction have run it very -close on some of these points, but have not--for reasons which will be -explained--affected the established position of the overhead system. - -In its essential features the overhead system has not altered very much -from the experimental line erected at the Paris Exhibition of 1881. The -slotted tube has been replaced by a solid copper wire; and the 'boat' -sliding within it has been replaced by a wheel or a bow pressed against -the lower side of the wire by means of a pivoted arm controlled by -springs. The sliding bow is common on the Continent, but it has been -adopted on only one British tramway--that at Sheerness. Its use for -electric traction on railways will be mentioned later, but as far as -British tramways are concerned the bow is the exception which proves -the trolley wheel rule. - -The function of the trolley wheel is to collect current from the wire -along which it rolls. This current passes through insulated wires down -the trolley arm to the controller, which the driver of the car operates -by means of a handle. The controller, which is really a series of -electrical resistances, is analogous to a water tap. By its means the -current may be completely shut off from the motors, or allowed to flow -in varying degree as required by the speed of the car. In starting a -car, the driver moves the controller handle notch by notch, so as to -get a uniform rise in speed until the full current is allowed to pass -through the motors. With such a mechanism, supplemented by brakes, the -driver has the movements of the car under control. - -In a four-wheeled car, each axle is driven by a motor. In a bogie car -(one with a set of four wheels at each end) the axles of the larger -wheels of the bogie are each driven by a motor; but not directly. -Considerations of space make it necessary to keep the motor as small -as possible, but if a motor is to be small and also powerful it must -rotate at a high speed. On the tramcar, therefore, the motor drives a -small toothed wheel which drives a large toothed wheel fixed to the -axle, thus effecting a reduction of speed between the motor and the -wheel. - -The same considerations of space join with others in making two motors -on each car the general rule. And the use of two motors enabled the -tramway engineer to introduce a refinement into the method of control. -This refinement is known as the 'series-parallel system.' One of its -objects is to give a large 'starting torque' and so enable the car -to gain speed quickly. When the current is first switched on by the -controller it passes through the motors in tandem or in 'series,' -thus dividing the pressure of the current (analogous to a 'head' of -water) between them. The starting torque of a tramway motor (or the -turning moment which it exerts when current is first passed through -it) is dependent on the current but independent of the pressure. Thus -the tandem or 'series' arrangement, which passes the full current -through each motor, gives the maximum starting torque without an -undue consumption of current. After the car is well started, the next -movement of the controller puts the motors in 'parallel,' opening up -two paths for the current instead of one, so that each motor receives -the full pressure. The practical result is that there is a very rapid -acceleration at starting, with marked economy in current. If the motors -were kept in 'parallel' right through, twice as much current would be -required to get the same starting torque. It will be seen later how -valuable this arrangement for getting a rapid start, without excessive -current consumption, may be in improving the physical and economic -conditions of a tramway or train service. - -After having passed through the motors and done its work, the current -is led to the wheels of the car and returns by way of the rails, -which are linked together by copper bonds so as to form a continuous -conductor. The passage of the current from the wheel to the rail is -indicated by sparks when the rails are rough or very dry and dirty. -Although the rails, like the overhead wires, are thus carrying current, -there is no danger of shock from them, as the electrical pressure -in them is only a few volts, at the outside, while the pressure in -the overhead wires is 500 volts. It is this difference of pressure -which--like the 'head' of water in a turbine--supplies the motive power -for the car. - -Each car on a tramway system may thus be regarded as a bridge which -completes an electrical circuit. When the driver moves his controller, -current flows from the generating station at a high pressure, passes -through the controller, operates the motors, and returns to the -generating station at a low pressure. This typical circuit is completed -through every car, so that the demand on the generating station at -any moment is the sum of the demands of the cars at that moment. The -business of the engineer at the generating station is to maintain the -electrical pressure in the overhead wire at the normal level of 500 -volts; and in order to do this on an ordinary tramway system it is -found convenient to divide the overhead wire into half-mile sections, -each of which has a separate main or 'feeder' from the generating -station. The passenger can detect the change from one section to -another by the click of the trolley wheel across the gap which -insulates one half-mile section from another. At the same spot he can -see the short square 'feeder-pillar' at the roadside (containing the -switches by which current can be turned off from that section) and the -cables which pass along the arm of the trolley standard and terminate -in the overhead wire. - -On an extensive tramway system the power-supply arrangements become -more complicated. The central generating station remains the primary -source of power, but sub-stations are erected at convenient points -between the central station and the outskirts of the tramway area. -These sub-stations are secondary stations for the distribution of -electricity. They receive power at extra-high pressure (5000 volts or -more) from the central station; they contain special machinery for -reducing the pressure to 500 volts for distribution to the various -tramway feeders. The object of this arrangement is partly technical -but mainly economical. Electric power can be transmitted at a lower -cost in mains and with less loss of energy at high pressures than at -low. Consequently when the termini of tramway routes are several miles -from the generating centre, greater all-round efficiency is secured -by transmitting current at high pressure to a number of well selected -sub-stations. - - [Illustration: Fig. 4. Photograph of a car on a conduit section of - the London County Council tramways. The centre line on the vacant - track indicates the slot rail through which the 'plough' on the car - passes to make contact with the conductors in the underground conduit. - (Photograph reproduced by courtesy of Dick, Kerr and Company, Ltd.)] - - - - - CHAPTER VI - - CONDUIT AND SURFACE-CONTACT TRAMWAY SYSTEMS - - -Roughly speaking, the arrangements for generating electricity, -distributing it, and utilising it on the car, remain the same in -conduit tramways and surface-contact tramways as on the overhead -system. The differences between the three systems are, as already -indicated, confined to the means of collecting the current for each car. - -Both the conduit and the surface-contact system were suggested as a -means of escape from the main objection to the overhead system--the -exposure of 'live' wires in the street. The cable tramway, with its -concrete trough and slot, gave an obvious hint. There would be no -difficulty, apparently, in carrying wires on insulators in the trough -or conduit, and utilising the slot for a 'plough' which would slide -along inside the conduit, keeping contact with the wires, and so -conveying the current to the car. - -This was tried for the first time in Blackpool, where--in 1884--a -length of conduit tramway was laid along the front street of the town. -The conditions could hardly have been less favourable for the system, -as the sea frequently washed over the roadway, flooding the conduit -with water and sand. Further, the conduit was so shallow that children -were able to get at the conductors with their metal spades. As the -conduit carried the return wire, the effect of a metallic contact -between the two conductors was to cause a 'short circuit,' with very -entertaining fireworks but with no amusing results for the tramway -engineer. After a heroic trial, the system had to be abandoned. - -Bournemouth was the next British town to adopt the conduit. It did so -as a token of its exceptional civic pride. Three times, in fact, the -Bournemouth Corporation declared that it did not want tramways of any -kind whatever within its gates. And when the pressure of public opinion -forced its consent, the arrangement was made that no overhead wires -should appear in the central district of the town. Several miles of -conduit tramway were therefore constructed (the trolley system being -used for the outer tramway routes); and as by that time a good deal of -experience had been gained in conduit work both in America and on the -Continent, the contractors were able to give the Corporation a conduit -system built to endure. At first the Corporation was reconciled to the -fact that the conduit sections had cost about twice as much per mile as -the trolley lines, but as years went on, and as the financial results -of the system continued to prove unsatisfactory, the Corporation's -contentment became modified. An examination of the accounts showed that -the conduit sections could be reconstructed on the overhead system at a -cost equal to the annual expense of maintaining these sections in good -working order. Since the public had got used to the overhead wires on -the other sections, and since they had not got used to owning tramways -which produced a heavy loss, the decision was made to abandon the -conduit system altogether. - -In London the conduit system was adopted by the London County Council -for various reasons. One was that the Council felt that London ought -to have the best, the very best, and nothing but the best. Another -was that the streets were so congested with traffic, lamp standards, -telegraph and telephone poles, and other obstructions, that trolley -wires and trolley standards would be a great nuisance and a serious -danger. Aesthetic reasons were also advanced, but it is difficult to -realise that they had much weight in connection with the majority of -metropolitan streets. Trolley wires were, in fact, freely erected in -suburban streets where there was a certain amount of beauty worth -preserving. - -The main underlying reason, no doubt, was the feeling that London could -afford the most costly system. In any ordinary city (and perhaps in -London as well) the conduit must be regarded as a luxury. It involves -a continuous road excavation so deep that a great deal of incidental -work has frequently to be done in moving gas, water, and drain pipes -out of the way. The conduit itself is a thick channel of concrete, -strengthened at intervals of a few feet with heavy cast iron 'yokes' -which support the 'rails' forming the lips of the slot through which -the 'plough' of the car passes. Elaborate arrangements have to be -made for draining the conduit, as any accumulation of mud or water -in contact with the conductors, or the special insulators supporting -them, would be fatal to the working of the system. And in practice -the ordinary drainage has to be assisted by continual scraping of the -conduit with special brushes and by repeated flushing during the hours -when the cars are not running. Heavy rains and snowstorms are therefore -liable to upset the working of the system; and the tramway manager has -to employ quite an army of men simply to keep the conduit in working -order. - -Trouble is also apt to be caused by purely mechanical means. On -one occasion a child's hoop fell through the slot and caused a short -circuit. As the ordinary scrapers slipped over the hoop, its presence -was not detected for a considerable time, during which the tramway -service was at a standstill. Altogether there is a greater liability to -interruption on the conduit system than on the overhead system. - - [Illustration: Fig. 5. The upper portion of the illustration shows a - section of a typical conduit system of electric tramway traction. - This section is taken at one of the cast-iron 'yokes' which support - the rails forming the slot through which the 'plough' passes from - the car to make contact with the conductor rails. - - The lower illustration gives a longitudinal and transverse section of - the 'G-B.' system of surface-contact tramway traction. The rope-like - cable carries the current and is supported on insulators. When the - collector on the car covers the stud, the action of the magnet draws - the lower part of the stud into contact with the cable, thus supplying - current to the car. After the car has passed, the lower part of the - stud rises by the action of a spring and, breaking contact with the - 'live' cable, becomes dead. (In actual practice contact would be made - under the conditions shown in the left-hand diagram.)] - -Experience of these drawbacks led the London County Council to seek -an alternative to the conduit when constructing electric lines in the -north of London. Many of the borough councils, following the County -Council's own previous arguments, would not listen to the suggestion -of the overhead system; and a freshly-elected Council, pledged to a -policy of economy, determined to try the surface-contact system. How -this trial gave rise to a violent political controversy, leading to -the abandonment of the project and culminating in important libel -actions, forms a picturesque story which need not be told in detail -here. Its main interest lies, for the moment, in the emphasis which the -incidents give to a characteristic of the surface-contact system--its -sensitiveness to minute alterations in detail. - -The surface-contact or 'stud' system is really a modification of the -conduit system. It has, in fact, been called the 'closed conduit.' -The electric wires are again placed in a channel or pipe underground, -but instead of being accessible through a slot, contact can be made -with them only through metal studs placed at intervals flush with the -roadway. By special electro-mechanical devices in the stud and on the -car, the stud is brought into contact with the 'live' underground wire -only when the car is over it. That is to say, the studs covered and -protected by the car will be 'live' and supplying power to the car -through a sliding brush or 'skate,' while those not so protected will -be 'dead' and therefore of no danger to the public. - -An immense amount of ingenuity has been expended by many engineers in -devising studs to act with absolute certainty under all conditions. -In the laboratory or the workshop, and even on an experimental track, -it was simple enough to arrange a mechanism which would 'make' and -'break' contact with admirable regularity. But when it came to putting -the mechanism down on an ordinary roadway, to be covered with mud, -pounded by heavy traffic, and subjected to the action of damp, frost, -heat, and all sorts of unexpected influences, much less satisfactory -results were obtained. Time and again the hopes of engineers were -dashed by a succession of petty troubles--some of them obscure, most -of them unforeseen. The weak points in nearly all the systems were the -insulation of electrical parts and the road construction work. Lack -of simplicity and rigidity led to the introduction of moisture and to -the shifting of parts so that studs jammed and remained 'alive' after -the car had passed over them. But even after the practical elimination -of these troubles the success of the surface-contact system seemed as -sensitive as the system itself. - -One system was tried at Torquay, and discontinued after a protracted -trial on a large scale. Another system--the Lorain system--was -installed at Wolverhampton and is still in operation, but without -imitators. A third system--the Griffiths-Bedell or G-B. system--was -installed in 1905 at Lincoln, with satisfactory results. It was the -G-B. system which was offered to the metropolitan borough councils as -an alternative to the conduit and the trolley. A trial section was -laid down in 1898 in the Bow Road, and a certain amount of trouble was -experienced with live studs and with various parts of the equipment. -Owing to the stud system having been suggested by the Moderate Party, -the experimental difficulties were extensively advertised by members -of the Progressive Party, who condemned the system as dangerous and -unworkable. Public feeling was worked up to such a pitch that, in the -face of expert advice in favour of the system in a somewhat modified -form, the Council decided to abandon the experiment. Libel actions by -the owners of the 'G-B.' patents followed, part of the plaintiffs' case -being that the system as laid down was altered in a number of small but -vitally important details by the Council's officers and was therefore -not the 'G-B.' system proper. - -The results with the 'G-B.' system at Lincoln prove that it is -possible to construct surface-contact tramways at a cost about 10 per -cent. more than that of trolley tramways, and to operate them, safely -and with reliability, at a cost not appreciably more than the general -working expenses of an overhead line. But this proof has not only been -enfeebled for the special reasons just described, but it came at a time -when the public had got quite accustomed to the trolley and also when -most towns had already been equipped with electric traction. Ten or -fifteen years earlier, such a proof might have changed the course of -tramway development; now it can have no great material effect. - -The upshot of the contest between the three systems has, therefore, -been the survival of the one which was most despised at the outset. - - - - - CHAPTER VII - - THE BACKWARDNESS OF ELECTRIC TRACTION IN GREAT BRITAIN - - -Popular objections to the overhead system are not, of course, quite -dead. Every tramway proposal in districts where the trolley has not -already penetrated is still opposed on the ground of disfigurement -and danger. This opposition serves as an index to the severity of the -struggle which the advocates of the trolley system had to encounter -before they made it almost universal in large cities. But the dislike -of the public for a questionable novelty was not the sole reason why -electric tramway enterprise was backward in Great Britain. - -It is not strictly accurate to say that electric tramway _enterprise_ -was backward. The enterprise was there, in spirit, but circumstances -were very much against it. Tramway schemes are controlled by special -legislation which was passed before electric traction was contemplated; -and this legislation has not been amended in any material degree to -suit the altered conditions brought about by the use of electricity. - -The Tramways Act, 1870--which is the master Act of the situation--was -framed at a time of reaction against public monopolies. Before that -time, gas, water, railway, and other companies had been granted -statutory powers in perpetuity; and when a local authority wanted to -take the supply of gas or water into its own hands, it had to buy the -existing undertakings at the valuation put upon them by the owners -themselves. There were frequent complaints about excessive purchase -terms, and also about extortionate rates charged by the monopolist -companies. Consequently, when horse tramways came on the scene, the -legislature determined to put the new 'monopoly' on quite a different -basis. The Tramways Act provided, first, that no application for -tramway powers would be so much as considered if it did not gain the -consent of the local authorities interested; second, that the period -of tenure should be limited to twenty-one years; and third, that the -local authorities should have the option, at the end of the period or -at seven-year intervals afterwards, of buying the tramway undertaking -at the 'then value' of the plant (rails, horses, cars, depots, etc.) -without any allowance for compulsory purchase, goodwill, future profits -or any other consideration whatsoever. - -This Act was passed with the very best of intentions. It had the -advantage of substituting, for the costly and clumsy procedure by -Private Bill, the simple and cheap process of applying to the Board -of Trade for a 'Provisional Order' which would acquire the full -force of an Act when ratified (in a more or less automatic way) by -Parliament. But in spite of its good intentions it proved a serious -stumbling-block, especially when electric traction was proposed. - -The effect of the limited tenure system, with compulsory expropriation -on what were called 'scrap-iron' terms, was to make the companies very -reluctant to spend one penny more than was absolutely necessary during -the concluding years. Capital expenditure on improvements in equipment -was regarded as out of the question, since there was not sufficient -time to recoup the difference between first cost and the 'then value' -at the purchase period. Money was grudged for the upkeep of track, the -repair and painting of cars, and the hundred and one items of expense -which are essential to a well-conducted tramway. System after system -fell into a state of shabby gentility, hoarding money against its -inevitable end. - -This was the condition when, in the middle eighties, electric traction -was suggested. The public, suffering from the decay of the tramway -service, but not realising that the cause lay with an Act devised for -the public benefit, expected the tramway companies to adopt the new -mode of propulsion. But as the conversion to electric working involved -track-work costing several thousands of pounds per mile, and new cars -costing several hundreds each, together with a large generating plant -and new car depots, the change was commercially impossible to companies -which were forced to retain their old horse equipment in order to -realise something for the shareholders in the day of expropriation. -From these causes there arose a demand that the municipalities should -take over the tramway systems and do what the companies appeared too -slow to undertake. - -Thus a strong impetus was given to municipal tramway enterprise. But -this impetus did not remove the causes of delay. The local authorities -had good economic reasons for waiting until the existing tramway leases -ran out and so enabled purchase to be made upon the most advantageous -terms. They were also obliged to move very cautiously in adopting so -radical and so novel a change as electric traction. Municipalities are -not speculative traders, who are ready to take risks after a rapid -expert investigation of a new policy. Further, no municipality likes to -accept the decision of another as valid for its own district. - -The consequence was that each municipality thought it necessary to -get its own expert report on the subject and, in many cases, to send -its own deputation to inspect Continental tramway systems. These -preliminary studies, with debates in Council chambers and newspaper -columns, with public meetings of encouragement or protest, and with the -erection of experimental lines, took up so much time that little of a -substantial nature was done until several years after engineers were -ready and willing to carry out the conversion of large systems of horse -tramways to electric working. - -The municipalities, however, were not the only forces at work. Towards -the year 1896, when a large number of tramway leases were running out, -a considerable amount of business was done by private capital in buying -up horse tramways with a view to conversion and also to extension far -beyond the limits of the existing routes. The essential condition of -the success of such enterprise was, of course, the renewal of the -tenure of the tramways for at least another twenty-one years. Here--and -in the accompanying applications for extensions of route--the true -inwardness of the Tramways Act was shown. Everything was in the hands -of the local authorities. They had only to withhold their consent, and -nothing could be done. And this power of veto enabled them to drive any -bargain they pleased with the promoters of tramway schemes. - -Most electric tramway proposals covered the areas of several local -authorities, so that negotiations had to be entered into with each in -turn. The municipalities, being the guardians of the public interests, -considered it their duty to impose the heaviest conditions which -the promoters could be induced to accept, rather than abandon the -enterprise. It was a case of Hobson's choice in every parish. In some -instances direct payments for wayleaves were demanded. In others the -promoters were forced to bear the cost of street widenings and other -'public improvements' which were not always necessary for tramway -purposes. In nearly every town the fares and stages were determined by -the local authority--on the strength of the veto, not on commercial -principles. The cost of construction was frequently increased by -onerous conditions regarding the standard of overhead wire and track -work. Under the Tramways Act, tramway companies were compelled to -maintain the roadway between the rails and also outside for a space of -eighteen inches--a provision which was sensible enough when horses were -used. But the condition was not only enforced within these statutory -limits when the promoters were about to use a form of traction which -spared the road surface; it was extended in numerous cases to an -obligation to pave the entire roadway and to maintain it--often with -expensive wood paving where macadam had previously been considered -quite good enough for the traffic. - -One effect of this state of affairs was delay. The preliminary -negotiations with local authorities--the interviews with mayors, -aldermen, councillors, town clerks, and borough surveyors, to say -nothing of the 'frontagers' along the line of route--usually occupied -far more time than the actual construction of the tramways. They were -also much more troublesome, since it was within the power of a single -local authority in a central position to 'hold up' a complete scheme, -while most districts had strong local patriotism and wanted a municipal -system to themselves. Very little is known by the general public of -the anxiety, difficulty, and expense attending such negotiations -with local bodies divided into parties or cliques and furnished with -an absolute power of veto. Looking back on the history of electric -traction, it really seems extraordinary that engineers and financiers -had the patience to undertake this work and carry it through. Their -reward, as will be seen, was not great in a pecuniary sense; and, as -regards reputation, they are generally accused of being extravagant, -avaricious, and wanting in enterprise. - -The ultimate effect was that the actual cost of electric tramways -exceeded the estimates prepared on the basis of Continental and -American experience. The more prolonged and difficult the negotiations -preliminary to a scheme became, the greater the expense. And the -conditions imposed by local authorities as the price of their consent -loaded the capital account of electric tramway undertakings with items -which had no direct concern with the tramway. The Board of Trade -assisted the increase in cost by prescribing a standard of construction -which was higher than that allowed in other countries. The net result -has been that while electric tramways were expected to cost about L9500 -per mile, they have actually cost over L12,000 per mile. - -The revenue side of the account has also been affected by the power -of veto. A local authority has no hesitation in imposing low fares -and long stages (with high wages and short hours for employees) upon -a tramway company seeking its consent. The standard usually adopted -is that of large urban systems with dense traffic, so that systems in -scattered districts are often unfairly treated. In municipal systems -themselves the fares are apt to be determined by the promises of -councillors at election times rather than by the simple consideration -of a fair price for improved traffic facilities. Workmen's fares, for -instance, are a dead loss on practically every tramway system. Every -now and again there is an agitation for halfpenny fares, for the -extension of stages, for cheap rates for school children, for free -transport for the blind, and so on. A leading municipal tramway manager -once remarked that it was almost impossible for men in his position to -resist the pressure for such concessions, especially at local election -periods. The chairman of the Highways Committee of the London County -Council recently stated that never a day passes without some appeal for -concessions in tramway fares. - -Most of the large urban systems are under municipal control, and -therefore they have the rates in reserve, as well as the most -favourable traffic conditions, to encourage them in giving the public -more and more for less money. But the tramway companies, working for -the greater part in less thickly populated areas, with no extraneous -means of making up losses, are put in a difficult position when similar -concessions are forced upon them. The upshot is that the average return -on the capital of electric traction companies amounts to only 3.41 per -cent. Better profits were, in fact, made in the horse tramway days; and -the electric traction industry is a fine example of the way in which -the enterprise of engineers and capitalists may bring little comfort -to themselves but enormous benefit to the public, which shows its -gratitude by asking for greater blessings at their expense. - - - - - CHAPTER VIII - - ELECTRIC TRAMWAY STAGNATION. THE TROLLEY OMNIBUS - - -The revenue of a tramway is built up of pennies; and a minute increase -in the average earnings per passenger will therefore have a large -effect on the total receipts. For instance, it was calculated (in -1907) that an increase of one-tenth of a penny in the average fare on -the sixty systems under the control of the British Electric Traction -Company would mean an increase of over L200,000 in the revenue. -Similarly, a fractional decrease in one of the operating expenses--say, -the cost of electric current--might transform a shaky undertaking into -a sound one. Tramway finance, in fact, is a question of infinitesimals. - -So long as fares are determined by arbitrary conditions, little can -be done to increase the revenue on an electric tramway system. Such -matters as the weather and the extent of building operations have far -more influence on tramway traffic than anything the tramway manager can -do to assist it. Apart from the development of parcels traffic, his -best opportunities lie in the skilful adjustment of the service to the -varying needs of the public, so that the 'rush' hours find an adequate -supply of cars, while the quieter hours find no 'waste car mileage' -in the form of empty cars. He can also do a good deal in the way of -inducing the drivers not to waste current. By putting an electricity -meter on each car it is possible to check the current consumption and, -by a system of bonuses, to encourage the economical driver. There -are many other directions in which small financial leakages may be -arrested, giving an aggregate saving which is well worth the trouble. - - [Illustration: Fig. 6. Photograph of an electric trolley omnibus - built by the Railless Electric Traction Company Ltd. in 1909 and - operated at Hendon for experimental purposes. Later cars built by - this company are of a lighter and simpler design, but the illustration - shows clearly the arrangement of a double trolley for supplying - current to a vehicle which 'steers' like an ordinary motor omnibus.] - -The fact remains, however, that on the whole the electric tramway -business depends upon too narrow a margin between costs and receipts. -The recognition of this fact, coupled with the legislative difficulties -already described, led to the practical cessation of tramway -development in Great Britain at a point far short of what was once -expected. At one stage, no doubt, people were a little too enthusiastic -about electric traction. They imagined that electric traction would -create profitable traffic along the most deserted of side streets. -Acting on that theory, municipalities constructed--or forced tramway -companies to construct--lines along roads which could never supply -enough traffic to justify the expenditure involved. The interest on -capital and other standing charges for an electric tramway route are so -substantial that a certain minimum of traffic density must exist before -any profit at all can be earned. - -However, after every allowance is made for such local excesses of -enthusiasm, the under-developed condition of electric traction in -Great Britain remains conspicuous enough. A sensible relaxation of -legislative restrictions would go a long way to improve matters--if, -that is to say, financiers could be induced to re-enter a field in -which they have had many disappointments. - -Great hopes of improvement were entertained when the Light Railways -Act, 1896, was passed. The primary object of this Act was to encourage -the building of cheap railways for agricultural and fishery purposes, -but it was drafted on lines broad enough to include electric tramways. -Arrangements were made for State and local contributions to the cost of -such schemes, in cases where subsidies appeared to be justifiable. The -procedure in obtaining powers was made as simple and as economical as -possible. Applications for 'Light Railway Orders' had to be made to the -Light Railway Commission, one of whose members then arranged to hold a -local inquiry into the proposal. If sanctioned, the scheme was passed -on to the Board of Trade for approval, and the Order, if confirmed, -thus secured the validity of a Private Act of Parliament. - -Nothing was said in this Act about the consent of local authorities, or -about limited tenure, or about expropriation upon scrap-iron terms. But -the Light Railway Commissioners chose to interpret the Act in terms of -the Tramways Act, with the result that, when there was any opposition -on the part of local authorities, the tramway promoter using the Light -Railways Act was not much better off than before. He had to face a new -difficulty in a clause of the Light Railways Act, which provided that -when the proposed light railway was of sufficient magnitude and in such -a position that it offered competition with an existing railway, the -scheme should be submitted to Parliament as a Private Bill--that is to -say, should face the most costly and cumbersome procedure of all. - -The Light Railways Act thus proved a great disappointment. Its failure -to afford relief seems to have taken away the tramway promoter's last -hope of genuine legislative betterment. He has resigned himself to -things as they are; and the utmost he does is to assert, when occasion -offers, that there are many districts which might enjoy the benefits -of electric traction if means were provided for bringing every scheme -directly before an independent tribunal for consideration on its merits -alone; if arrangements were made for obtaining wayleaves and land on -favourable terms, and if he were allowed to construct and equip the -line on a less costly basis than the Board of Trade now demands, even -in rural districts. - -Pending that revolution, tramway authorities are seeking to develop a -cheaper means of electric traction than the tramway. At the present -stage, urban tramways have spread through suburbs towards villages -and small towns which are anxious for better transport facilities -but have not sufficient population to justify a tramway extension. -Inter-urban tramway systems--those connecting towns with a network of -lines--are also adjacent to such minor centres of traffic. From time -to time attempts have been made to meet the demand by means of petrol -omnibuses, but they have rarely been successful--partly, no doubt, -owing to the difficulty of working a limited petrol omnibus service -economically at the extremities of an electric tramway system. - -The latest solution of the problem is the 'trackless trolley' or, more -correctly, the 'trolley omnibus.' In the 1911 session over a dozen -tramway authorities applied for powers to use this device; and, if the -financial results of the first attempts are successful, there will -probably be a considerable growth in this type of electric traction. - -The trolley omnibus is a hybrid between the trolley tramcar and the -omnibus. It is akin to the first, because it derives its power from -an overhead wire through a flexible trolley pole. It is akin to the -second, because it does not run on rails but is fitted with solid -rubber tyres and uses the surface of the road in the usual way. - -Roughly speaking, its electrical equipment is similar to that of -a tramcar. The trolley pole conveys the electric current to the -controller, which admits it to motors geared on to the back axles. -There are, however, one or two important differences. The absence of a -rail which might act as a return conductor necessitates the provision -of a second overhead wire and a second trolley-pole to connect with it. -Thus the electrical circuit is from the power station, along the first -overhead wire, down the first trolley-pole, through the controller and -motors, up the second trolley-pole, and back by the second overhead -wire to the power station. Owing to the vehicle being a steerable -one, the trolley-poles have to be specially designed to give plenty -of free play sideways. The vehicle itself is similar in appearance to -a single-decked motor omnibus, and it runs on solid rubber tyres or -spring wheels. - -The first thing which strikes one about the trolley omnibus in -comparison with the electric tramcar is the cheapness in first cost. -All the expense of concrete foundations, heavy rails, and granite -paving is avoided. On ordinary roads the overhead construction is -much less costly, as a single line of poles supporting two wires is -sufficient for the up and down services. Estimates show that the -equipment of a mile of roadway on this system will cost only from -one-fourth to one-third of the corresponding tramway system. Following -on this economy there is the saving in the cost of maintenance and -repairs--a serious item on the ordinary tramway. In actual working, the -system has the advantage that the vehicles can steer past slow-going -traffic, thus avoiding the delay caused on tramway systems through -carts having to draw out, away from the track, when overtaken by cars. -This steering or 'overtaking' power enables a trolley omnibus service -to be maintained without obstruction on a narrow roadway which would -be badly congested by tramcars running on a rigid track. When there -is only one pair of wires, two trolley omnibuses may pass each other -(whether going in the same or opposite directions) by the simple -process of pulling down the trolley poles of one car and swinging -them out of the way for a few seconds. On a single-line tramway it is -necessary to provide loops at intervals for crossing purposes and also -to arrange the service so that cars arrive at the loops simultaneously. - -The other side of the picture is shown when we come to look into the -costs of working. - -No matter how good the road surface may be or how excellent the design -of the wheel, the tractive effort required for a trolley omnibus -must be relatively greater than that required for a tramcar. Nothing -demands a lower tractive effort than a steel wheel running on a steel -rail. Consequently the trolley omnibus takes more power per ton moved -than the tramcar. When the road surface is wet or uneven, or muddy -or loose, this difference is of course multiplied. Another addition -to the working cost is produced by the tyres, which, if of rubber, -may wear away at the rate of 1-1/2_d._ or 2_d._ per mile per vehicle. -Owing to the uniform control of speed afforded by the electric system, -there is less jerking at starting or stopping than is general with a -petrol-driven omnibus; but in spite of that advantage, tyre wear on a -trolley omnibus must remain an important item. Something must also be -allowed for the effect of vibration upon the car body and electrical -equipment--an effect which is of course much less pronounced when a -vehicle runs on rails. - -The balance between these advantages and disadvantages is not easy -to strike, even on a general basis. And it varies so much under local -conditions that tramway engineers debated a long time before they -decided in certain cases to try the trolley omnibus in extending their -traffic facilities. All they had to go upon was the experience gained -on certain Continental routes, where trolley omnibuses have been -running for several years. That experience encouraged the hope that -trolley omnibuses might be a profitable means of developing traffic in -conjunction with a tramway system, and along routes which would not -provide sufficient business for a regular tramway. - -The simultaneous adoption of the trolley omnibus on a number of tramway -'feeders' gave rise to an impression that tramway authorities had -discovered the wheel-on-rail system to be less efficient than the -tyre-on-road system. As a general proposition, nothing could be further -from the truth. Tramway authorities have adopted the new system in -certain cases where the possible traffic is comparatively small, not -as a substitute for tramways, but as an alternative to self-propelled -omnibuses. The carrying capacity of a trolley omnibus is about twenty, -while that of a tramcar is frequently as high as seventy. The speed of -a tramcar runs up to twenty miles an hour, while twelve miles an hour -is as much as is comfortable (to say the least) with a vehicle running -with solid tyres on an ordinary road. - -Therefore, where large volumes of traffic have to be handled swiftly, -the tramway will remain. But where a twenty-minute or half-hourly -service of small vehicles is sufficient for the available passengers, -a system which is much cheaper in first cost is clearly more suitable, -even though it may not reach the standard of economy in working set by -the large urban tramway. That is to say, the choice between the two -systems depends entirely upon local circumstances. - - [Illustration: Fig. 7. The 'auto-trolley' system of electric traction - applied to the haulage of goods in a German quarry. (From _Electrical - Industries_.)] - -As an emphasis upon this statement, it is significant that many -tramway engineers regard the trolley omnibus merely as the forerunner -of a tramway. For this reason they favour the adoption of the -particular trolley omnibus system where the overhead equipment is -adaptable with trifling changes to tramway purposes. They argue that, -in the case of a village of a few thousand inhabitants, situated a mile -or so beyond the terminus of a tramway route, a trolley omnibus service -will not only be sufficient for the existing traffic, but will show -whether the traffic is likely to increase (through the stimulation of -building enterprise) up to the point where it would make the laying of -rails worth while. When that point is reached, the rails will be laid -and the trolley omnibus vehicles put on some other route which is at -one and the same time a tramway 'feeder' and a tramway 'feeler.' - - - - - CHAPTER IX - - REGENERATIVE CONTROL - - -Before going on to discuss the 'accumulator' or 'storage battery' -system of electric traction, reference should be made to an invention -which holds the germ of great economies in electric traction. This -invention is known under the name of 'regenerative control.' - -It has already been explained that the dynamo is reversible--that is -to say, a dynamo may act as a motor, or a motor as a dynamo. This fact -is usefully applied in braking tramcars. When a car has gained speed, -its momentum represents a certain amount of stored energy. In stopping -the car, this energy has to be absorbed or dissipated in some way or -other. One method is to utilise the friction of brake blocks on the -wheels, or of skids on the rails themselves. With the electric car, -however, it is possible to absorb the energy by making it drive the -motors as if they were dynamos. The moving car drives the wheels, which -in turn drive the motors; and the current so generated may either be -absorbed in electrical 'resistances' or led to electro-magnets which -are so placed that they exercise a retarding pull on the rails. In any -of these cases a car which is being stopped, or is being 'held back' -by the brakes when going down-hill, is wasting power. It is clear, -therefore, that a great deal of power could be saved if the current -generated by the motors in retarding could be pumped back, as it were, -into the electrical circuit. - -This is the problem of 'regeneration' which has fascinated many -electrical engineers. The practical difficulties underlying it are very -great; and perhaps the only man to get within measurable distance of -surmounting them was Mr J. S. Raworth, whose system of regenerative -control was tried on a number of tramway systems and installed on the -Rawstenstall tramways in 1909. It cannot be said with confidence that -all the difficulties have been overcome; on the other hand, it would -be rash to say that they are insurmountable. Mr Raworth, at any rate, -retains his faith in ultimate victory; and the theoretical beauty of -the system is so complete that it is bound to retain its fascination. - -The practical result of regeneration is to eliminate the effect of -hills. A regenerative car in descending a hill gives back to the -generating station some of the excess energy required to take it up the -hill. In the same way each car, in coming to a standstill, gives back a -portion of the energy required to start it. A regenerative tramway may -thus be represented, from the energy point of view, as one in which all -the cars are running at normal speeds on level roads. - -Incidentally the regenerative system gives a very perfect control -of the speed of the car on all gradients, owing to the regeneration -which begins automatically when the motors start 'coasting.' It is a -power-saver and a brake in one; and its efficacy as a means of control -is so great that, if its incidental drawbacks could be avoided, it -would be worth adopting for this purpose alone, both on electric -tramways and on electric railways. - - - - - CHAPTER X - - ACCUMULATOR ELECTRIC TRACTION. THE ELECTRIC AUTOMOBILE - - -The use of the accumulator or storage battery in electric traction -affords a very good example of how a means of propulsion may fail -in one set of circumstances and contrive to succeed in another. Its -history serves to remind us that the problem of cheap transport is -really a group of problems, each one of which demands a particular -solution. - -The accumulator is a device for storing electrical energy in the form -of chemical energy. Its action depends upon the effect of currents of -electricity on lead plates in a bath of sulphuric acid. The passage -of the current through the battery produces chemical changes which -enable the battery to give out current when required. As the battery -may remain 'charged' for several days, and may be discharged slowly -or quickly, it provides a means of 'storing' electrical energy. In -practice, and under favourable conditions, the efficiency of the -storage battery is about 80 per cent. That is to say, there is a loss -of about 20 per cent. in the process of conversion and re-conversion. - - [Illustration: Fig. 8. A modern electric automobile.--The electric - battery is placed under the front half of the car, and the motors - drive the back axle through chains. (British Electric Automobile Co., - Ltd.)] - -Great hopes were once entertained of accumulator traction on tramways. -The storage battery offered a means of escape from all the difficulty -and expense of carrying electric mains overhead or underground. -By fitting each car with a storage battery, it could be made an -independent self-contained locomotive, capable of running a certain -number of miles until the battery was approaching exhaustion. By -providing centres where the batteries could be re-charged--or, to save -time, replaced by batteries previously charged--a continuous service -could be maintained on a tramway system. - -The advantages of accumulator traction, apart from the saving in -first cost, are the absence of obstruction and danger from overhead -wires, and of the risk of a general stoppage of the service when the -current at the generating station fails from any accidental cause. -When accumulators are used, the conversion of a horse tramway to an -electric tramway becomes a very simple matter. All that is required -is to erect a generating station and provide each car with a storage -battery and electrical equipment. This equipment, it may be mentioned, -is substantially the same as with ordinary electric cars. The current -flows from the accumulator through the controller and the motors back -to the accumulator. - -Many trials were made with this system in the early days of electric -traction, but there are no survivals. The failures were due in part to -weaknesses in the batteries and to the difficulty of handling them with -proper care under the rough and ready conditions of tramway service. -The main cause, however, was the inherent drawback of all locomotive -systems--the fact that the tractor has to haul its own dead weight in -addition to the weight of the car and passengers. Lead being one of -the heaviest of metals, this dead weight was a very serious item on -accumulator tramcars. It proved to be a fatal item when the attempt -was made to run large cars on heavy gradients. The rush of current -demanded in starting such cars up-hill was in itself too severe a tax -on the delicate structure of the batteries. In practice, moreover, -the necessity of bringing each car back to the depot for re-charging, -after a limited journey, proved very troublesome. The more extensive -the system and the more frequent the service, the more troublesome this -necessity became. Even the most enthusiastic advocate of the storage -battery was at last forced to admit that it was not applicable to a -system of transport, which demanded comparatively high speeds with -large cars on all gradients and over a range of several miles from the -centre of power. - -After the admitted failure of accumulator tramways, the storage -battery was for some time used only on river launches and small -private vehicles. The conditions in both cases--and especially in the -former--are very favourable to its operation. On a river launch the -weight of the battery is not a serious item, as it serves to some -extent in the place of ballast. Launches, moreover, are generally -required for trips of a limited number of miles up and down the river -from the boathouse or charging station of the owner. In contrast with -the tramway, there is no demand for rapid acceleration at starting -or for abnormal power at intervals. The batteries discharge slowly -and fairly evenly, and are not subjected to serious vibration. The -electrical equipment is extremely simple, as the motor is fixed on to -the propeller shaft and operated by a controller on the deck close to -the steering wheel. - -However, if economy were the only consideration, it is doubtful whether -the electric launch would have survived against the competition of -steam and petrol launches. It has survived because the simplicity of -the equipment, its silent running, and the absence of heat, smoke and -fumes, make it the ideal thing for river work. The hire of an electric -launch on the Thames costs more than that of a steam launch, but -plenty of people are willing to pay the additional charge to avoid the -drawbacks of steam propulsion on a small vessel. - -Similar considerations underlie the extensive use of electric -broughams in cities. Such vehicles are required only for travel within -a restricted area and on streets where the gradients are seldom -severe. Their carrying capacity is generally limited to two or four -passengers, so that the batteries do not require to be unduly heavy. A -maximum speed of 12 miles an hour is quite sufficient for city streets; -and with careful treatment the batteries can be very economically -used and will not deteriorate nearly so rapidly as they would under -tramway conditions. Considerations of economy, on the other hand, -do not weigh very heavily with the class of people who use private -electric broughams. They are prepared to pay for the best available; -and the electric brougham, with its noiselessness, its easy running, -its absence of smell or other nuisance, is regarded as the ideal which -other modes of city transport must do their best to approach. - -In London a certain amount of business has been done for some years -in hiring electric broughams for various periods on terms which -include current, maintenance, garage facilities, driver's wages, and -all other charges. The convenience of such an arrangement to the -hirer need not be emphasised, since what is wanted in this case is a -vehicle which is always ready at a telephone call. But the system has -another important advantage, which bears upon the economic prospects -of accumulator traction. By retaining the vehicles under its control -the hiring company not only centralises the arrangements for storing -and re-charging, but it is able to take care that the batteries are -properly treated. Just as the success of the surface-contact system -depends on minutiae of design, so the success of accumulator traction -depends upon minutiae of treatment. Carelessness in driving the -vehicles and in handling the batteries at the garage may transform -a perfectly satisfactory mode of city transport into an extravagant -nuisance. Consequently the success of this class of business depends -upon an organisation which permits of constant supervision over every -vehicle and every driver. - -A good deal of ingenuity has been exercised upon the electrical -equipment of broughams; and it is probable that further improvements -will be made. In some cases the front axle is driven by the motor; in -some cases the back axle. The earliest cars used toothed-wheel gearing -in order to reduce the speed of the small fast-running motor. Improved -types on this principle still exist, but there are some interesting -forms in which the motors are placed right at the hub of the wheels and -effect speed reduction and control by electrical means, without any -intermediate gearing. - -In addition to these improvements, the storage battery itself has made -a distinct advance in design and construction. It is more efficient, -more durable, and more reliable now than ever it was before. The closer -attention given to its treatment tends in the same direction; and -the result is that storage-battery makers and engineers have a very -accurate knowledge of what the accumulator will do at a certain cost -under certain conditions. The conditions being the variable factors -in the problem, and being in large measure determinable by choice, it -is rather remarkable that the engineers and financiers should have -selected, at the outset, the very conditions which were least suited to -the peculiarities of the accumulator. - -The attempt to adapt battery traction to tramway work is a conspicuous -case in point, but it is not perhaps so conspicuous in the public -memory as the efforts to organise electric cab and electric omnibus -services in London and elsewhere. These efforts have been made so often -and failed so regularly that they have made it difficult to obtain -capital for any form of electric battery propulsion. - -The electric omnibus has many of the drawbacks of the storage-battery -tramcar, but they are not so serious in the case of an urban service, -adequately met by small cars running at moderate speeds on short routes -with moderate gradients. It is possible that if recent metropolitan -electric omnibus enterprises had been as happy in their finance as in -their engineering, they would have succeeded well enough. But even in -their engineering they had to meet great difficulties. They sought to -protect themselves against excessive costs by entering into maintenance -agreements with the makers of the batteries; and although the terms of -these agreements were satisfactory enough, their validity depended on -careful treatment of the batteries by the drivers of the cars--a matter -which it is rather difficult to guarantee. Moreover, the number of -omnibuses put on the road was so small that the garage costs and other -standing charges were proportionally very heavy. With a larger fleet -and with efficient organisation, much better results might have been -achieved in spite of the inherent difficulties of the situation. - -Although the electric cab has the advantage of being a smaller -vehicle and therefore more adapted to economical propulsion by -storage batteries, the conditions of the cab service are not at all -favourable to the system. The essential feature of a cab is that it -should be available anywhere, to go anywhere at a moment's notice. An -accumulator-driven vehicle, on the other hand, is tied by an invisible -cord to the charging station. Even if charging stations were multiplied -enormously, the electric cab would have no real freedom of action, -since several hours are required for the process of re-charging. We -have only to compare the limitations of the electric cab with the -freedom of the petrol cab (which can renew its supply of petrol in a -minute or two at any motor depot) to realise that the roving commission -is not at all suited to the former. - -In 1899 a very bold effort was made to establish an electric cab -service in London. To inaugurate the service a procession of the cabs -was formed, but it excited more ridicule than serious interest. The -clumsy appearance of the cabs was against them; and their behaviour -was not satisfactory enough--as to speed and reliability--to overcome -the first unfavourable impressions. They soon disappeared, to add -another failure to the long list of disappointments in connection with -accumulator traction. - -The private electric automobile remains, however, because it has been -organised under conditions which suit the peculiarities of the storage -battery. Its survival, in conjunction with the failure of a similar -means of transit for tramway, omnibus, and public cab services, has -pointed to another direction in which the electric automobile should -be a commercial possibility. That is, in connection with the local -distribution of goods from large stores and other centres. - -The United States have given a very distinct lead in this matter. In -New York, Chicago, Washington, and other large cities the electric -automobile for private use is highly developed and there is also an -extensive service of electric vehicles ranging in size from a small -parcels van to a large lorry capable of carrying loads up to several -tons. No doubt the local cost of other means of transport has something -to do with this American development, which has, moreover, been -strongly supported by the companies which supply electricity to the -public. But the fundamental reason lies in the special character of the -service demanded. - -The vans belonging to a large store all start from a certain point -and return to it after journeys of limited range. Owing to the period -occupied in loading up, and also to the pre-determined hours of most -of the deliveries, there is no difficulty about affording the time -required for re-charging the batteries, or in arranging each journey -so that the vehicle returns before the batteries are exhausted. With a -standardised fleet of vehicles, it is possible to remove the discharged -batteries and replace them with charged ones in a few minutes. The -whole arrangement, in fact, is like a private automobile garage, with -the advantage that the probable demand can be forecast with a somewhat -greater degree of certainty. - -Steam and petrol-driven wagons run most economically on long steady -journeys at fairly high speeds, and the electric automobile does not -attempt to compete with them on these lines. But it offers competition -within city limits for door-to-door delivery; and its prospects are -particularly good for light parcel service, where the horse is still -maintaining its position against the petrol vehicle. The advantages -of the electric vehicle in neatness and noiselessness will certainly -secure its success if the cost can be proved to be not appreciably -greater than that of its rivals. - -Apart from the necessity of careful organisation, the main essential -of success in electric automobile work is a supply of cheap -electricity. Owners of private electric launches have to pay anything -from 8_d._ to 2_s._ 6_d._ per unit for re-charging their batteries, but -these high prices are due to the intermittent character of the demand -and also (in some cases) to the cost of providing machinery to supply -current at special pressures for particular launches. An electric -automobile garage, situated close to a public generating station and -offering a larger and more regular demand, will of course obtain -current much cheaper. And it is possible that arrangements may be made -for supplying electricity to automobiles at a much lower rate even than -that customary for general power demands. In the metropolitan borough -of Marylebone, for instance, an electric garage may obtain current -during the small hours of the night at 1/2_d._ per unit, which is half -the standard rate for power purposes. This low price is offered because -there is otherwise practically no demand at all for electricity during -these hours. If, therefore, a garage arranges--and the arrangement is -quite feasible--to charge its batteries overnight, the power bill may -be divided by two. - -The electric automobile has been used to some extent as a touring car, -but although journeys up to 100 miles have been performed on a single -charge, the time occupied in re-charging, and the difficulty of finding -convenient charging stations, are fatal to any development in this -field. - - - - - CHAPTER XI - - PETROL-ELECTRIC VEHICLES AND MAIN MARINE PROPULSION BY ELECTRICITY - - -Between the petrol-driven vehicle and the electric automobile there is -an interesting series of links provided by 'petrol-electric' systems. - -At one end of the chain, electricity plays an important part in -supplying power to drive the car. At the other end, electrical -apparatus is introduced merely as a form of transmission gear between -the petrol engine and the driving axle. The reason for attempting -the petrol-electric combination will be most readily understood by -considering the latter arrangement first. - -The petrol engine is a high-speed engine, capable of working most -satisfactorily when it runs at a uniform rate with a constant load. -On the other hand, the speed of the driving axle of a car varies from -a very much lower speed down to zero. It is therefore necessary, when -driving a vehicle with a petrol engine, to arrange some forms of -variable speed-reducing transmission gear between the engine and the -driving axle. The problem is further complicated by the fact that the -petrol engine is irreversible, has practically no 'starting torque,' -and has a very slight overload capacity. It has to be started running -'light' and then switched on to a low gear which gives sufficient power -to overcome the inertia of the car. As the speed of the car rises, -there have to be successive changes of gear. These difficulties are, of -course, accentuated when dealing with the heavy weight of an omnibus. - - [Illustration: Fig. 9. Elevation and plan of a petrol-electric motor - omnibus equipped by W. A. Stevens, Ltd. Directly behind the front - wheels is the petrol engine, driving a dynamo through a flexible - coupling. The dynamo supplies current to the motor directly behind - it; and the motor drives the rear wheels through a cardan shaft. The - transmission of power between the engine and the shaft is electrical - at all speeds.] - -Practically all the troubles with petrol motor omnibuses have resided -in the gear; and even the most ardent enthusiast for the all-electric -faith must admit that the motor engineer has overcome these troubles -(in great part if not wholly) with remarkable skill and ingenuity. -But the complications of an adjustable mechanical bridge between a -high-speed engine and a varying low-speed axle are so great that -an electrical bridge was proposed as a substitute. By coupling the -engine direct to a dynamo and by using the current so generated to -drive variable-speed motors geared to the driving axle, the electrical -engineer hoped to get better working results from the petrol motor than -could be obtained with any mechanical transmission gear. - -The most conspicuous advantage, apart from the quietness of running -at all speeds, lies in the ease and smoothness with which the -petrol-electric motor can start and gain speed. In this respect the -combination system is practically on the same level as (or even -superior to) the electric tramcar or the electric automobile. There -is an entire absence of the jerks and jarring noises which usually -accompany the starting of a motor omnibus. The same facility of control -is of advantage in adjusting speed to suit the other traffic on the -road, and also in negotiating hills. - -In one class of petrol-electric vehicles the electric transmission gear -is continuously used. In another, it is used at all speeds except the -highest, when the engine is coupled directly (by a magnetic clutch) -to a mechanical driving gear. In a third class the arrangement is -more complicated, as it involves the use of storage batteries as an -auxiliary to the power provided directly by the petrol engine. The -Fischer type of petrol-electric vehicle uses electric transmission -solely and has a fairly large battery to supplement the engine-produced -current when steep hills are being negotiated. At ordinary speeds on -level roads the surplus power produced by the engine goes to charge the -battery. - -The 'Automixte' type is peculiar in using the mechanical transmission -gear all the time. The dynamo coupled to the engine supplies current to -a small battery when surplus power is available; the same dynamo may -be driven as a motor by current from the battery when such assistance -is wanted at starting or on steep hills. The electric part of the -equipment thus acts first as a generator and then as a motor, the -change taking place automatically. - -These different petrol-electric devices are very attractive from the -engineering point of view, but at the present time it is uncertain -whether they will realise the hopes of their inventors. The additional -weight of the electric equipment is against them; and in some cases -there appears to be a lower all-round efficiency. So that the -motor-omnibus world, as a whole, continues to fix its faith upon the -improved forms of mechanical transmission. - -The underlying idea of the petrol-electric system has, however, been -suggested for marine propulsion with a somewhat better prospect of -success. - -There is a partial analogy between the conditions of motor omnibus -working and of ship propulsion with turbines. The steam turbine -is, like the petrol engine, essentially a high-speed machine. The -screw propeller, on the other hand, works most efficiently at low -speeds. Therefore the marine engineer has to try and find some -common denominator between an engine which runs most efficiently -at high speeds and a propeller which is at its best when revolving -comparatively slowly. - - [Illustration: Fig. 10. Diagrammatic section of a steamship which - has been 'converted' from the ordinary method of propulsion to the - 'Paragon' system of electric main marine propulsion. The reciprocating - engine has been replaced by a steam turbine, coupled direct to an - electric generator which supplies current to a motor attached to the - propeller shaft. The tests carried out with this vessel will indicate - the advantages of the electric method of propulsion even with the - usual long length of shaft. The vessel has a gross tonnage of 1241, - and its speed is 9 knots. The engines replaced ran at 78 revolutions - per minute and gave 500 brake horse power. The turbine now installed - runs at 2500 r.p.m., and develops 630 brake horse power. (Illustration - reproduced by courtesy of _The Electrician_.)] - -The gulf between the two has been narrowed by the improved design -of propellers. Some engineers assert that continued improvements will -bridge the gulf completely. Others have sought the solution in the -same way as the motor engineer--by the use of mechanical change-speed -gears. The suggestion has also been made to employ hydraulic gear as -an intermediary; and in some recent vessels reciprocating engines with -comparatively low-speed turbines driven by exhaust steam have been -adopted. - -In the electric system the turbine is coupled direct to an electric -generator and may run continuously at the highest economical speed. -The propeller shaft may be quite short and is driven by a slow speed -motor connected by cables to the generator. Various arrangements for -controlling the supply of current to the motor (with appropriate -design of generator and motor) have been devised by Mr Durtnall, Mr -Mavor, and other workers in this field; but whatever the details of -these arrangements may be, they all give a wide range of speed both -ahead and astern. The direct drive with the steam turbine has really -only one speed--full speed ahead; and as the turbine is irreversible, -'astern' turbines have to be installed in addition. These limitations -and complications are removed entirely when electrical transmission is -adopted. - -Moreover, the electric system can be so arranged that the control gear -may be operated from the bridge itself. The facility in manoeuvring is, -in fact, so marked that it would recommend electric marine propulsion -even if that system offered no advantages on the score of economy -in weight, space, and steam consumption over the existing systems. -The steam turbine, it may be noted, has been adopted so far only in -high-speed vessels; and it is generally recognised that its extension -to vessels which run at 12 or 16 knots depends upon its adaptation to -slow-speed propellers. Advocates of electric marine propulsion claim -that they hold the most efficient solution of this problem. - -It may also be pointed out that a considerable section of marine -engineers look forward to the use of internal combustion engines -(driven by oil or gas) on board ship. For naval purposes especially -it would be a great advantage to do away with funnels and so leave -the decks more free for gun mountings. As internal combustion engines -are irreversible, the electric system offers a means of escape from a -fundamental drawback to their use at sea. Here again the perfection of -manoeuvring power, especially with twin screws (either of which may -be controlled from the bridge through a wide range of speed ahead or -astern), gives the electric system a strong claim for consideration by -the naval authorities. - -It is hardly necessary, except as a matter of curiosity, to refer to -the suggestions made, from time to time, of accumulator-driven ocean -steamships. Some wonderful pictures have been published of large -vessels with tons of ballast in the form of storage batteries. They are -likely to remain in this ideal condition, for although the driving of a -large vessel by stored electricity is quite possible, it is also about -the most expensive method which has ever been proposed. - -Electric power from storage batteries has been used as an auxiliary -in the propulsion and manoeuvring of submarines. In aerial navigation -electricity has so far been employed to a very limited extent. Small -airships have been designed to carry electric accumulators connected -with various motor-driven propellers for raising, lowering, going -ahead or astern, and steering. The switches which control the passage -of the current to these propellers are connected with a wireless -telegraph receiver, so that each operation may be started or stopped -by a particular ether wave or series of waves. Demonstrations of such -'wireless-controlled' airships have been given in theatres; their -field of usefulness, if any, is in connection with war on land or sea. -Whether they will have any better fate than other devices for dropping -bombs over the enemy's camps or ships remains to be seen. - -One inventor has, I believe, suggested a means of direct electrical -propulsion for aeroplanes, the current being derived from a -petrol-driven generator and carried to motors attached to propellers so -arranged as to give certain advantages in stability and manoeuvring. -As yet, however, the probability of electricity being applied to -locomotion in the air as well as on land and on sea is somewhat remote. - - - - - CHAPTER XII - - THE PIONEER ELECTRIC RAILWAYS - - -Electric tramways have reached a period of middle age in which they -are more concerned about their internal economy than the prospect of -enterprise in new directions. Such development as they feel capable -of making under present legislative conditions is only by proxy and -tentatively, with the aid of the trolley omnibus. - -Electric railways, however, have still many worlds to conquer. They -are now in much the same position as electric tramways held about the -year 1896. That is to say, they have already given practical proof of -their capabilities and enabled engineers to point out the directions -along which they are certain to develop. In the railway world there -is a growing conviction that the adoption of electric traction on all -suburban and inter-urban railways must be simply a matter of time. For -main line traffic the possibilities of using electricity are as yet -only an article of faith among electrical engineers. - -Although the earliest experiments in electric traction were made in -the railway form, the first electric lines could hardly be regarded -as railways in the ordinary sense. They were really light railways, -in which the traffic conditions approximated to those of tramways. -The routes were short, the cars small, and the traffic of modest -dimensions. They contained the germ of both the tramway and the -railway; but, in the case of the railway, many years of technical -development had to pass before the problem of applying electricity -to the handling of large masses of traffic under standard railway -conditions was solved. - -The fact that the first electric railway in the United Kingdom was -constructed at the Giant's Causeway (in 1883) is significant. The -Giant's Causeway is one of the few places in our islands where water -power is available close to a district with a demand for traffic -facilities. In 1885 another electric railway deriving its energy from -water-driven turbines was built between Bessbrook and Newry. At that -period it was considered that waterfalls provided the only really -feasible source of cheap electricity on a large scale. Even yet the -impression survives that electric power stations using steam cannot -produce current so cheaply as those which 'harness' waterfalls. Many -people, in fact, are inclined to attribute the comparative backwardness -of electrical development in Great Britain, not to legislative -conditions, but to the lack of large waterfalls. - -There might have been more active progress in the pioneering days -if the presence of water power at convenient points had encouraged -electrical engineers to repeat the experiments at Portrush and -Bessbrook. But at an early stage in electrical history it became clear -to engineers that coal was just as feasible a source of cheap power -as water. The idea that a waterfall provides power 'for nothing' -is one of those superficial conceptions which make the hardiest of -fallacies. To 'harness' a waterfall requires a heavy expenditure of -capital on conduits, pipe-lines, dams, and other works. The interest -upon that capital is a heavy item, apart from the cost of maintenance -and repairs. Waterfalls are situated in mountainous country, generally -remote from the centres of industry; the water-power station, -therefore, has to face the cost of transmission mains and the loss -of energy involved in conveying the power to the place where it is -wanted. Further, waterfalls and the adjacent ground belong either to -individuals or to the State; and payment is generally exacted for the -right to use them. - -All these items have to be covered in the price charged for current to -the public or to railway undertakings. Nature may provide the 'head' of -water 'free,' but man has to spend money in utilising it, just as he -has to do in mining and in obtaining heat from the coal which is also -provided 'free.' Anything which is obtained 'for nothing' is generally -worth nothing. - -The full economies of generating electricity by steam power are -not, however, realised until business is done on a large scale. As -the first essential of a successful electric railway is a plentiful -supply of cheap power, development from the experimental stage of -Portrush had to wait until engineers mastered the art of producing -electricity from large generators. They gained the necessary experience -with electric tramways and in electric lighting. We have seen how, -as regards tramways, legislation delayed and hampered progress. A -similar cause was at work in connection with electric lighting. In -1882 an Act was passed regulating electric lighting on lines modelled -upon the principles of the Tramways Act, 1870. Capitalists declined -to work under this Act; and it was not until after 1888, when the -Act was amended, that any money could be found in Great Britain for -electric lighting schemes. This delay was a serious handicap not -only to electric lighting but to the business of British electrical -manufacturing, as there was, comparatively speaking, no demand for -electrical plant for over six years. Meanwhile, matters had been -advancing on normal lines in other countries; and when the demand came -at last, the manufacturers on the Continent and in America were the -only ones organised and ready to meet it. - -These points must be touched upon in order to understand why so long -a period elapsed between the pioneer electric railways and the real -electric railway movement as we know it to-day. They also serve to -explain the prominent part which American and German firms took in -electrical developments here. Engineering and legislative conditions -combined to retard electric railway enterprise so that it did not begin -to take firm root in Great Britain until about 1890, and did not attain -to any conspicuous growth until the beginning of the twentieth century. - -Until after 1890 the only electric railways in Great Britain taking -power from steam dynamos were those at Brighton Beach, Ryde Pier -(Isle of Wight) and Southend Pier, opened in 1883, 1886 and 1890 -respectively. These were all, of course, of short length. The Brighton -Beach railway, designed and constructed by Mr Magnus Volk, was a unique -piece of work. The rails were laid on heavy concrete blocks below -high-water mark; and the cars were platforms raised on a light iron -structure. Power was conveyed to the cars from wires hung on posts like -the standards of a tramway on the trolley system. The unusual sensation -of travelling over the water was enjoyed by hundreds of people until -the difficulty of maintaining the track (owing to the erosive action of -the waves) led to the railway being abandoned and another line of more -ordinary character being laid on the level of the undercliff roadway. - -The first indication of the genuine electric railway movement was given -in 1893, when the Liverpool Overhead Railway was opened. This line was -constructed to afford communication along the line of docks fringing -the Mersey. The track was carried on a continuous bridge in order to -avoid obstruction between the docks and the streets behind; and being -overhead, there were serious disadvantages attached to the use of steam -locomotives. Electric locomotives were therefore employed. - -In this case, it should be noted, electricity was not adopted because -it was more economical or efficient than steam. The reason lay with -the peculiar situation of the railway. A similar reason decided -the promoters of the City and South London Railway to try electric -locomotives on their line. This railway, which was opened in 1890, was -the first deep level or 'tube' railway in the world. Moreover, it was -constructed and equipped throughout by British engineers, and at a time -when the art of tunnelling was much less advanced than it is now. In -the later and more imposing development of tube railways in London, -the foresight and enterprise displayed by the pioneers of the City and -South London Railway are apt to be overlooked. It was, however, the -success of the original line from the Monument to Clapham which made -it possible to raise capital for the Central London Railway (opened -in 1900) and for the extensive tube railway system organised by the -Underground Electric Railways Company of London. - -On a deep-level railway, steam is, of course, out of the question. Even -on the old 'Underground,' built close to the surface and furnished with -frequent openings at the stations, and by means of ventilating shafts, -the atmospheric conditions were abominable. The sulphurous fumes were -indeed recommended for asthma and other complaints, but on a tube -railway they would have been sufficient to cure every human ailment. -Therefore the choice lay between electric traction and haulage by -cables, compressed air, or some other innocuous system. Within these -limits electricity was chosen on its merits. - -The first railway in Great Britain to undertake conversion was one -in which both the physical and economic troubles were exceptionally -serious. The Mersey Railway is little more than a tunnel under the -river, and it is distinguished by heavy gradients and by the continuous -necessity of pumping out the water which drains into it. With steam -traction the difficulty of ventilating the tunnel was an added trouble. -Owing to these various causes the working expenses were abnormally -heavy, and led ultimately to a receivership. Electric traction was -adopted as the only possible cure. The pumping and ventilation -arrangements were both reorganised for electric power; and the trains -were equipped with electric traction on the 'multiple-unit' system, an -arrangement--to be described in the next chapter--which is well suited -to the economical handling of steep gradients. The practical result was -a great increase in traffic, with a marked decrease in the proportion -of expenses to receipts. - -No other British railways, happily, were in so desperate a condition -as the Mersey line, but all of them were, at the end of last century, -feeling the effect of certain disquieting tendencies. These tendencies -were most marked in connection with suburban and short-distance -inter-urban traffic, which is quite distinct in character from the -main-line traffic. We talk glibly enough of railway traffic as if -it were a unity, but it is clear that very different considerations -govern the traffic on a main line between, say, London and Glasgow, -and those which control the traffic on London suburban routes or on a -railway connecting the adjacent towns of the Potteries. Some railways -have to deal with all three classes at the same time and occasionally -on the same lines of rails. Electric traction has, so far, made itself -felt only where the suburban or similar inter-urban traffic has been -separable from the main line traffic. - -The growth which took place in suburban traffic before and after -the end of the century ought to have brought increased prosperity -to the railway companies, but it did not always do so. Competition -between the various companies led to a reduction in fares; Parliament, -by establishing workmen's fares, forced the companies to carry an -ever-increasing number of passengers at a loss, or at least without -profit; wages tended to increase and hours of working to decrease--both -affecting the cost of operation; rates and taxes became heavier and -heavier with the growth of municipal expenditure; and a higher standard -of comfort and efficiency was demanded by the public. In some instances -the situation was aggravated by the competition of electric tramways -along routes parallel to the railways. This competition was limited to -point-to-point traffic, its maximum range being about three miles; but -it was a grievance against which the railway companies protested very -loudly, especially when the tramways were owned by local authorities to -which the railways paid large sums in rates. - -The general effect of all these factors was to reduce the margin of -profit on which the railways were working. We have seen, in the case of -tramways, how easy it is for a slight change in a frequently-recurring -expense to have a serious effect in the aggregate. Railways are in -much the same position; and the various influences at work upon the -suburban traffic brought them face to face with the importance, if not -the necessity, of finding some means of dealing with larger volumes -of traffic on a basis more economical than that provided by steam -locomotives. - -This means they found in electric traction; but it may be noted that -even railway engineers took some time to realise exactly what electric -traction offered them. They were looking for something to reduce -their annual expenses; and when they made calculations about electric -traction they found that, when the expense of providing the electrical -equipment was taken into account, the total cost of hauling the trains -electrically on the existing schedule might be greater instead of less -than the cost of steam haulage. They were therefore inclined to look -upon the economic benefits of electric traction as an illusion. - -In course of time, however, it came to be recognised that the function -of electricity is not to act like a blue pencil on the debit side of -the revenue account. Its essential purpose is to increase the volume of -traffic. From the public point of view this is very much more valuable. -Passengers are not directly concerned with means of reducing working -expenses, but they are closely interested in the improvement of the -frequency and speed of the service. The adoption of electricity on -suburban lines has really been dictated by the demand for increased -facilities. At the 'rush' hours of the morning and evening, when -the great tide of workers flows and ebbs, the capacity of the steam -lines was taxed to the utmost. And with the growth of population the -difficulty of running sufficiently frequent trains became almost -insuperable. - -Apart from these particular necessities, the general features of -railway economics point to the supreme advantage of increasing the -volume of traffic in every possible way. In a railway, as in a tramway, -the preponderating item is the cost of construction and maintenance; -and unless a certain minimum of traffic is carried, the most economical -working in the world will not secure a profit. The standing charges -fall upon the idle hours as well as upon the busy; for every minute -that a line of rails stands empty there is a loss of money. Railway -progress depends upon reducing the proportion of idle hours; and that -can only be done where there is scope for the growth of traffic, and -where there is means--such as electric traction--of dealing with that -growth on an economical basis. - -In the succeeding chapter it is explained how electric traction -enables a more frequent service to be run with advantage even on -systems which were worked to the maximum limit possible under steam -conditions. But in the meantime it will be interesting to trace the -effect itself on a railway which soon followed the Mersey Railway in -making the change from steam to electricity--the Metropolitan District -Railway. - - [Illustration: Fig. 11. An electric train on the Metropolitan District - Railway, equipped by the British Thomson Houston Company. The front - and rear cars and one intermediate car are equipped with electric - motors, all controlled from the 'cab' at the end of the train. The - controller handle may be seen close to the nearest window of the first - car. The rail immediately in front of the foot of the guard is the - conductor rail which conveys the current to the train. The rail - between the track rails carries the return current.] - -Throughout the steam age the finance of the District Railway Company -was as unattractive as the physical conditions of the railway itself. -No dividend was ever paid on the ordinary shares; and even with the -growth of London there was little prospect of any dividend ever being -paid. When--about ten years ago--the late Mr C. T. Yerkes came over -from America and obtained a controlling interest in the District -Railway Company with a view to converting it to electric traction, he -was regarded as a philanthropic enthusiast. Many of the shareholders -themselves were reluctant to give their assent to the change; they -preferred to bear the ills they knew than fly to others which might be -introduced by an American financier. - -But Mr Yerkes and those who worked with him had something more in -view than the improvement of traffic on the District Railway. They -acquired control of several tube railway schemes and obtained powers -for new lines, so as to organise a comprehensive system of underground -electric transport in London. They had sufficient faith in the traffic -possibilities of London to find the enormous capital required to -construct these tube railways and also to convert the whole District -Railway to electric traction. The constructional work occupied several -years; and after the lines were opened one by one, arrangements had to -be developed for through-bookings among the various lines and between -them all and the existing underground railways like the Central London -Railway, the Metropolitan Railway (closely linked with the Metropolitan -District) and the City and South London Railway. A systematic attempt -was also made to develop the travelling habit in London by persistent -advertising of the railway services and by increasing the frequency -and rapidity of the trains. From these points of view the organisation -of the network of lines comprehensively known by the title of -'Underground' is certainly unsurpassed. - -The difficulties which had to be overcome in this great work were -enormous, but there has been no break in the thread of progress. -The 'tubes' are paying dividends which, though modest, are an -encouragement to further developments. The finance of the District -Railway has lost its element of chronic despair. Considered as a -whole, the results prove that where there is the potentiality of large -traffic, electricity is the instrument which must be applied. During -the steam days, the most crowded part of the District Railway (the -'Inner Circle') carried a maximum of 16 trains per hour. With electric -traction that figure has been raised to 40 trains per hour. And the -remarkable thing is that with each increase in the service the traffic -grows. Many people welcomed the electrification of the District as a -measure of relief from the overcrowding on the steam trains during the -busy hours. But with a service of trains more than doubled in frequency -and also increased in capacity per train, overcrowding continues and -the 'straphanger' has become an established institution. - -It may be accepted as substantially proved that, on suburban and -inter-urban railways in populous districts, electric traction is a -means of increasing traffic and diminishing the proportion of working -costs. Moreover, these results have been achieved in conjunction with -substantial reductions in fares and with marked improvements in the -comfort of travelling. - -The engineering aspect of these changes has now to be considered. - - - - - CHAPTER XIII - - ELECTRIC RAILWAYS FROM THE ENGINEERING POINT OF VIEW - - -When electric railways were first considered, the natural tendency -of engineers was to follow the existing model and merely substitute -electric locomotives for steam locomotives. In point of fact, however, -the engineering method now adopted is an evolution from the tramway -model, not from that of the typical railway. - -A certain advantage was, of course, to be gained by replacing steam -locomotives by electric ones. The greater 'starting torque' of the -electric locomotive enables it to get a train up to full speed more -quickly; and the capacity of the electric motor for taking heavy -overloads assists the electric train in surmounting heavy gradients. -Some advantage was also gained by producing all the power at a central -source, instead of having a large number of steam locomotives, which -are really power stations on wheels. But the electric locomotive had -still to be made heavy enough to get sufficient grip of the rails; -it had to haul its own dead weight; and it had to be made powerful -enough to tackle a full-sized train on the steepest gradient with its -complement of passengers, although the general demand upon it might be -considerably less than that maximum. - -The electric locomotive, in short, was an advance upon the steam -locomotive, but it did not get past the essential drawbacks of the -locomotive system. A locomotive is most economical when hauling full -trains for long distances at a uniform speed; it is essentially a -long-distance machine. The first demand for electrification came, -however, from suburban railways, where the stations are close together -and where, therefore, the speed is constantly varying from zero up to -a maximum and back to zero again. The traffic also fluctuates between -extreme limits; and there is obvious waste in having to run heavy -locomotives and trains backwards and forwards during the slack hours. -There was therefore a demand for some method of propulsion which would -enable the length of trains and the consumption of power to be adjusted -more closely to the variations in the traffic. - -A step in the right direction was taken when the locomotive equipment -was placed on a car, thus utilising the weight of the passengers to -increase the adhesion on the rails. But the full advantages of electric -traction were not realised until what is known as the 'multiple-unit' -system was adopted. - -The idea underlying this system is quite simple. If, instead of -concentrating the motive power on a single locomotive or driving -unit, we distribute it among the cars forming a train, we get the -multiple-unit system. An electric tramcar and a trailer attached -to another tramcar and trailer, with a third tramcar behind, would -form a model for a multiple-unit train. By connecting the electrical -equipments on the three tramcars--front, middle, and rear--it would be -possible to control the train from either end or from the middle. - -This is the principle upon which all the electric railways in Great -Britain are now worked, with the exception of the City and South London -Railway, where locomotives are still used and where the trains are -comparatively short and light. - -It will be seen that each multiple-unit train is readily divisible. A -single motor car may be run, or a car with one or two trailers, or a -long train made up of as many motor cars and trailers as the platforms -will accommodate. And whether the trains are long or short, the power -absorbed is in proportion to the length of the train and the load of -passengers. By this simple means power is economised, and the railway -engineer is able to reduce the proportion of idle rolling stock. - -The adjustment of the length of trains to the fluctuations of the -service is made easier by the absence, in the multiple-unit system, -of the necessity of shunting at the termini. As a multiple-unit train -can be controlled from either end, a more frequent as well as a more -flexible service can be run. With steam traction the number of trains -which may enter or leave a terminus is limited by the time occupied in -shunting and by the necessity of leaving lines of rails free for that -operation. With an electric train on the multiple-unit system, no more -time is lost than the few seconds necessary for the driver to walk from -the front of the train to the rear, which then becomes the 'front.' -No lines have to be kept open for shunting locomotives, so that the -available accommodation for trains is considerably increased. Some of -the London railway companies have spent enormous sums in enlarging -their terminal accommodation and have found that it is still inadequate -to the demands of the 'rush' traffic. Electric traction therefore -offers them an improvement of enormous value without the expenditure of -a penny on station alterations. - -The crowning advantage of electric traction lies, however, in the more -rapid acceleration which it affords. We have already seen how important -this item is on tramways. It is still more important on suburban -railways, where a high average speed, in spite of frequent stops, is a -vital matter. - -On the District Railway the rate of acceleration in the old steam -days was about 6 inches per second per second. It was, in fact, so -low that the trains could not reach a fair speed before the brakes -had to be applied to bring the train to a stop at the next station. -With electric traction the rate of acceleration has risen to about -18 inches per second per second. On the Liverpool Overhead Railway a -rate of 36 inches per second per second was reached in certain tests. -Heavy starting currents are, of course, necessary to bring a train from -rest to full speed at such a rapid rate, but it is quite possible for -the electrical engineer, without being unduly extravagant in current, -to accelerate a train more quickly than the passengers would find -comfortable. - -The practical result of rapid acceleration (combined with rapid -braking) is not only to give a higher average speed but also to enable -a more frequent service to be run. Owing to the block system on -railways it is impossible for trains to follow each other closely in -the manner of tramcars; and it is therefore of cardinal importance that -no train should occupy a block for one second more than is necessary. -Rapid acceleration becomes all the more important in this respect -because of the difficulty of setting down and picking up passengers -quickly. This difficulty is overcome in part by using saloon carriages -with middle and end doors, in place of compartment carriages. At first -the District Railway tried to help matters by operating these doors -pneumatically, but the mechanism became unpopular after a number of -late-comers had been pinched by closing doors. The management has -reverted to hand operation; and it has probably achieved more by -educating the public to move quickly than it would have gained with its -too-perfect mechanical system. - -London travellers have become so accustomed to entering and leaving -trains quickly that it is possible for an observer to distinguish -strangers by their slower movements on an underground railway. Thus -the passenger, as well as the service, has been 'speeded-up.' The more -frequent service of trains with a higher average speed would not have -been possible, however, without an improvement upon the old methods of -signalling. There is no need to dwell upon the weakness of the human -element in railway signalling; and it will be clear even to the layman -that the strain of handling traffic with a headway of one minute and a -half, or less, would be more than men could stand. Automatic signalling -had therefore to be adopted to obviate the risk of disaster. - -Each train, as it leaves a block or section, 'clears' the signals -for that block; and when any train attempts to enter a block against -signals, the current is automatically switched off and the brakes -applied. The system is so perfect that, in spite of the enormous -traffic worked under it, there has been no failure and no accident. -It is, of course, costly to install; and its cost can be justified -(financially) only when the traffic is very heavy--that is to say, when -the conditions make it almost a necessity. - -The supply of electric power to electric railways is organised on -practically the same lines as in the case of tramways. That is to say, -current is generated at a central station, transmitted at high pressure -to various sub-stations, and supplied from there at working pressure -through 'feeders' to each section of the system. In the case of the -'Underground' system, most of the power is taken from a single huge -electric station at Chelsea. Current from that station drives trains as -far west as Wimbledon, Hounslow, and Ealing, as far north as Highgate -and Golder's Green, and as far east as Barking. - -This is a magnificent example of the concentration which gives -economy. If each of the underground railways forming the system had -erected its own generating station, the total initial outlay, on -land, buildings, and machinery, would have been greater, and the -cost of current would have been higher, owing to the smaller output -and the more irregular demand which a single railway affords. The -ideal electric power station is one which is constructed with the -largest generating units and produces current at its maximum capacity -throughout the twenty-four hours of each day. The Chelsea power station -is nearer the ideal than a smaller one supplying a short railway could -be. And a station of the latter class is, it may be noted, nearer the -ideal than the arrangements on a steam railway, where the sources of -power are scattered in hundreds of locomotives. - -The concentration of power is therefore one of the many factors which -have enabled electric railways to give a vastly improved service at -lower fares. - -With two exceptions--to be considered in the next chapter--the electric -railways of Great Britain are constructed on the 'third-rail' system. -They are thus a reversion to--or, rather, a survival of--the original -type adopted by Siemens in 1879. The 'third-rail' is carried on -insulators a few inches outside the track rail; and the motor cars are -provided with a 'brush' or 'shoe' which slides along it and collects -the current. In the centre of the track there is generally a second -insulated rail to carry the return current, as it is more convenient, -under railway conditions, to have a conductor independent of the track -rails than to follow the tramway plan of using the rails 'bonded' -together. In stations and at crossings the third or 'live' rail is -protected by a wooden board in order to reduce the risk of shock to -anyone falling on the line or walking upon it. The board is placed high -enough over the rail to allow the shoe to pass freely. - -As regards the motor equipment on the cars, tramway models have been -followed very closely. The 'series-parallel' system of control is again -adopted in order to get the high starting torque which gives rapid -acceleration with moderate current consumption. The course of the -current is again from the live rail, through the controller, through -the motors, and thence to the return rail. The controller itself is -more or less on the tramway principle; and the main modification in -it is the arrangement which enables all the motors on a multiple-unit -train to be operated by a single controller. This is done by connecting -the controllers electrically and using electric power so that they all -work in unison. Some companies use, for this purpose, compressed air -controlled by electricity instead of electric power alone, but in both -cases the principle is essentially the same. - -Considered as a whole, the difference between a tramway and an electric -railway on the third-rail system is a difference in degree, not in -kind. The traffic is greater and the speeds higher, but both serve -the purposes of comparatively short-distance transit. Indeed, within -certain limits they compete with each other. - -There remains to be considered another type of British electric -railway which points the way to the extension of the new mode of -traction to main line railways. - - - - - CHAPTER XIV - - ELECTRIC TRACTION ON MAIN LINE RAILWAYS - - -On tramways, automobiles, and 'third-rail' lines, the electric current -used belongs to the type described as 'continuous' or 'direct,' -because the flow is always in the same direction. The other type -of current is known as 'alternating,' as it flows backwards and -forwards many times per second. There are several kinds of alternating -current--single-phase, two-phase, three-phase, and polyphase--each -produced from generators designed in a particular way. - -It is not possible to give any adequate account of these different -kinds of alternating current without going rather deeply into the -theory of electricity. The ultimate practical point is that in -transmitting alternating currents the circuits increase in number with -the phases. Thus, three-phase current requires three wires, two-phase -current three or four wires, and single-phase current a single circuit -like that of continuous current[1]. - - [Illustration: Fig. 12. Photograph of a train on the electrified - section of the London, Brighton and South Coast Railway. The overhead - wire is suspended from cables stretched between insulators, and - current is conveyed from it to the trains through a 'bow' which slides - along its lower side. The photograph is taken from the rear part of - the train. The front and rear cars are both equipped with electric - motors.] - -Where current has to be conveyed economically over long distances, it -is generally done in the form of alternating current at high pressure. -For instance, the transmission from a tramway power station to the -sub-stations is almost uniformly by three-phase current at, say, 5000 -volts. When it reaches the sub-station, it is 'transformed' down to -the working pressure of 500 volts and 'converted' from alternating to -continuous current by means of rotary machinery. The transforming is -done by a stationary piece of apparatus similar in principle to the -familiar induction coil. An induction coil takes current at a few volts -from a battery into its primary circuit and transforms it, by induction -in the secondary circuit, into current of high enough voltage to give a -long spark. A transformer can be designed to 'step-up' or 'step-down' -the pressure according to the requirements of the case. - -So much explanation is necessary to give some account of the -alternating current railways on the Continent and thence of the -single-phase system on the London, Brighton and South Coast Railway. -The Morecambe and Heysham section of the Midland Railway is also -equipped on the single-phase system. - -Most of the earliest electric railways on the Continent derived -their power from waterfalls and had to transmit it for a considerable -distance. Three-phase current at high pressure being adopted for this -purpose, the Continental engineers set to work to find some means of -utilising the high-pressure three-phase current directly. They did this -by carrying the three wires on poles alongside the railway track, and -using three 'bow' collectors (in place of trolley wheels) to convey -the current to transformers on the motor cars or locomotives. In these -transformers the current was brought down to working pressure and then -led to motors designed for three-phase current. - -An immense amount of technical ingenuity was exercised in developing -this system; and when the Metropolitan Railway decided to follow the -District in electrifying its lines, a three-phase system was proposed. -As the Metropolitan and Metropolitan District companies share the -working of the Inner Circle, it was necessary that both should adopt -the same system. The result was that the question between three-phase -and continuous current working had to go to arbitration. After a -long discussion of masses of technical evidence, Mr Lyttelton, the -arbitrator, decided that the direct current system was better suited to -the conditions of traffic on an underground railway in London. - -The wisdom of that decision will not be questioned now. Three-phase -motors do not give the rapid acceleration which is so urgently required -on suburban lines; there are complications in speed control; and -the necessity of having three overhead conductors is also a serious -drawback. For comparatively long-distance traffic with few stops, -however, the three-phase system is quite suitable. That is to say, it -is a possible solution of the main line problem. - -The great simplicity and flexibility of the power supply arrangements -in the case of alternating current traction encouraged engineers to -find something better adapted to ordinary railway conditions than the -three-phase motor. Their problem was to find an arrangement which -required one overhead conductor instead of three, and also provided -a motor with the high starting torque and easy speed control of the -continuous-current motor. After much theoretical and experimental -work, they found it in the single-phase system, using a motor which is -similar in many respects to the continuous-current motor but capable of -being operated by alternating current. - -On the advice of Mr Philip Dawson, the London, Brighton and South -Coast Railway Company decided to experiment with this system on the -double line connecting London Bridge and Victoria stations, about -9 miles long. Power is supplied to each track by a single overhead -conductor carrying current at 6000 volts. Transformers are placed on -the trains to bring the pressure down to 300 volts; the current is -then led through controllers to single-phase motors in much the usual -way. The reason for using so high a pressure on the overhead line is -not only economy in transmission. If lower pressures were used, the -heavy currents required for train propulsion would require a thicker -conductor and correspondingly heavier supports. At 6000 volts it is -possible for two double sliding bows to collect sufficient current -for a heavy train from a wire which is comparable in thickness to the -ordinary trolley wire of a tramway. - -The power distribution arrangements, it will be noticed, are very much -simpler than with continuous current on the third-rail system. There -are no sub-stations with rotary machinery. Power is supplied direct -from the generating station to the overhead line and is transformed -down by stationary plant on the train itself. Single-phase traction -represents, in fact, power transmission for railway purposes reduced to -its simplest elements. - -The overhead construction differs, however, in some important points -from the tramway standard. The supports, which are in both bridge and -bracket form, are stronger; the insulators are, owing to the much -higher pressure employed, more massive; and a different means of -suspension has been adopted. Each conductor is hung by links from two -steel cables stretched chain-wise between the supports. This method of -'catenary suspension' enables the bow to slide along the wire without -the jolts which are noticeable with a tramway trolley. Such smooth -running keeps the bow continuously at an even pressure on the wire--an -advantage which is of great importance at high speeds. The trains are -arranged on the multiple-unit system. - -The full financial results obtained on this railway have not so far -been made public; but it is sufficient for our purpose to note that -the Company, after more than a year's full trial, extended the system -to the Crystal Palace and to Croydon. Further extensions are, it -is understood, contemplated over the suburban lines to Sutton and -elsewhere; and in course of time the conversion of the main line to -Brighton will be undertaken. - -Here we touch upon the most interesting aspect of this demonstration of -electric traction on the single-phase system. The system was adopted -in the first instance because the third-rail system would lead to -complications and dangers which could not be permitted at crowded -railway termini shared by all kinds of traffic, suburban and main line. -But the advisers of the Company had also in view the possibility of -development beyond the range of suburban traffic. They therefore sought -a system which, while comparable to the third-rail continuous current -in the handling of suburban business, would be adaptable to main line -conditions, where infrequent stops and long runs at high speeds are the -rule. - -The adoption of electric traction on such a route as the Brighton -main line would be a benefit in several ways. It would lead to a -faster express service, as the high overload capacity of the electric -motor enables it to take small account of gradients. It would also -lead to a more frequent service, as the electric system is free from -the conditions which force a steam railway to try to concentrate -traffic on a limited number of long trains. Further, it would, by -reducing the time lost in stopping and starting, bring the average -speed of stopping trains much closer to that of express trains. All -these improvements--assisted, probably, by lower fares--should lead -to a great increase in the volume of traffic, thus reproducing the -characteristic results of electric traction on suburban lines. - -[Footnote 1: An admirable explanation of alternating currents will be -found in Mr Frank Broadbent's _Chats on Electricity_. (Werner Laurie, -1910.)] - - - - - CHAPTER XV - - CURIOSITIES OF ELECTRIC TRACTION - - -Like many other industries, electric traction has had its history -brightened and made picturesque by curiosities of invention. Locomotion -has, in fact, been a favourite field for the freak inventor; and some -of his efforts with electric cars have been as weird and as fatuous as -the most remarkable of perpetual motion devices. - -One of these electrical monstrosities was, indeed, a kind of -perpetual motion arrangement. It was invented about the year 1890 and -consisted of a car equipped with accumulators which supplied power to -a motor which drove a hydraulic pump, which in turn worked a dynamo -supplying current to motors driving the axles of the car, and also to -the accumulator for re-charging purposes. The inventor was so sure that -he had got the better of the law of the conservation of energy that he -provided his car with pointed ends, fitted with revolving fans to break -down the air-pressure, in order that a speed of 125 miles per hour -might be achieved. His name was Amen; and it provides a fitting comment -upon his scheme. - - [Illustration: Fig. 13. Illustration of Elberfeld-Barmen hanging - electric railway. From _The Electrical Industry_ (Books on Business), - published by Messrs Methuen.] - -Several electric flying-machine ideas found their way on to the patent -records. In 1893 a Frenchman registered a design for an air-ship with -a cigar-shaped body and electrically-driven propellers. There was, -however, more originality in an American idea that the progress of -trains on the overhead railway might be assisted by the action of -balloons in taking the weight of the cars off the rails. Curiously -enough, other original inventors tried to get the opposite effect, by -devising magnetic arrangements to increase the adhesion of the wheels -to the rails. - -More plausible forms of super-ingenuity have been exercised in -connection with established modes of electric traction. - -For the conduit system one inventor suggested a kind of reversion to -the 'continuous valve' of the old atmospheric railway. The slot of the -conduit was closed by a continuous series of springs which would be -opened in succession by the plough as it passed along. This arrangement -was actually tried on an experimental track in London. Another inventor -proposed a novel plan for keeping the conductor in a conduit free from -damp. The conductor was to be made hollow, so that hot air could be -pumped through it to dry off any accumulated moisture. - - [Illustration: Fig. 14. The Heilmann electric locomotive--a generating - station on wheels. The general arrangement of this locomotive should - be compared with that of the modern electric turbo-locomotive - described on p. 130 and illustrated in Fig. 15.] - -The most entertaining freak in connection with the trolley system -was a device to enable two lines of car to use a single trolley wire. -Cars going in one direction were to carry a double-ended inclined plane -which would lift the trolley wheels of passing cars off the wire and -let them slip back again. The only drawback to this arrangement was -that it would not work. - -Another inventor who was apparently impressed with the noise of trolley -wheels on the wires designed a trolley head fitted with a pneumatic -tyre. If he could have persuaded indiarubber to be anything but one of -the best of insulators, he would have been completely successful. - -One of the best known of electrical freaks--the Heilmann locomotive -(Fig. 14)--is a very good example of the way in which an invention may -be tried with enthusiasm, rejected with contumely, and revived at a -much later date in an improved and more promising form. The Heilmann -locomotive was practically a generating station on wheels. It carried -a boiler and engines, which drove a dynamo, the current from which was -led through controllers to motors coupled to the wheel axles. It was -an enormous affair, over 18 metres long and running on sixteen wheels; -extensive trials were made with it on the Western Railway of France in -the early nineties. Some advantage was gained in smoothness of running, -ease and uniformity of control, and improved acceleration; but its -great weight, cost, and complexity were against it. In spite of the -cordial support given to it by railway engineers, it was soon relegated -to the scrap-heap. - - [Illustration: Fig. 15. Electro-turbo-locomotive built by the North - British Locomotive Company for experimental purposes. This locomotive - is a 'generating station on wheels.' It carries a steam turbine - driving a dynamo which supplies current through a controller to motors - geared to the axles.] - -The Heilmann locomotive, it will be noticed, is similar in principle to -the petrol-electric systems of propulsion now in use for road traction. -But it is probable that the idea would never have been heard of again -in connection with railway work had it not been for the appearance of -the steam turbine. It was natural that the locomotive engineer should -consider how the turbine could be applied to his purposes; and the -first step in this inquiry made it plain that some electric method of -control was necessary between the high-speed turbine and the driving -axle. - -Consequently, when the engineers of the North British Locomotive -Company set to work in 1909 to design an 'electric turbo-locomotive,' -they produced something not at all unlike the Heilmann locomotive. The -equipment consists of a steam turbine, with elaborate condensing plant, -a generator, and a group of driving motors (Fig. 15). The turbine runs -at 3000 revolutions per minute and drives a continuous-current dynamo, -the current from which passes through controllers to four motors which -can be run in series, or two in series and two in parallel, or all in -parallel, according to the draw-bar pull required. Trials with this -locomotive were begun early in 1910, but it is yet too early to say -whether it will be more fortunate than the Heilmann locomotive, and -whether it is likely to delay the advance of the electric locomotive -proper, fed with power by overhead wires from a central power station. - - [Illustration: Fig. 16. Diagrammatic sections of the Behr electric - mono-rail car. The car is balanced on the summit of a continuous - trestle and is designed for speeds up to 120 miles per hour.] - -The possibilities of high speed on a mono-railway, and especially -an electric mono-railway, have acted like a will-o'-the-wisp to the -imaginations of many engineers. Of the various systems suggested, only -one--the gyroscopic mono-railway invented by Mr Brennan--seems likely -to survive; and even in that case victory under practical conditions is -not yet certain. - -At Ballybunnion there is a steam mono-railway which has been at work -since 1888. It has had, so far as I am aware, no imitators; but its -engineer, Mr Behr, retained so much faith in the principle that he -decided to apply it to the problem of high-speed electric traction. -During the 1900 session he promoted a Bill for the construction of a -mono-railway between Liverpool and Manchester. There was tremendous -opposition from the existing railway companies, which brought experts -to prove that Mr Behr was a vain dreamer; but the Bill succeeded. The -promoters, however, found it much harder work to raise capital for the -project. They needed close upon L3,000,000, but the public response to -the first invitation was so small that the scheme was abandoned. - -The line, as projected, was nearly 35 miles long; and a speed -of 100 miles per hour was intended, reducing the time of the -Liverpool-Manchester journey to twenty minutes. At each end of the line -(which was a double one) a steep gradient was arranged to facilitate -starting and stopping--an arrangement, by the way, which is adopted to -a certain extent on London tubes. The track itself was shaped like an -inverted V, and practically the whole of the weight of the cars was -borne upon a rail at the top. The wheels, therefore, were right in -the centre of the car, which balanced itself on the trestle with its -centre of gravity below the rail. Each side of the trestle carried two -guide-rails which bore against free-running horizontal wheels on the -car to prevent any undue lateral movement. Each car was designed to -carry four motors with a total normal capacity of 160 horse power and -an overload capacity up to 320 horse power. The rails for carrying the -current were placed on the track in very much the same position as the -ordinary rails occupy on a normal railway. - -In another form of mono-railway--the Kearney high-speed railway--the -wheels are placed below the car and run on a single rail laid direct -on sleepers. The cars are held upright by flanged wheels on the top, -running on a rail fixed to the roof of tunnels or to standards not -unlike those of an overhead trolley. This railway has been exhibited in -the form of a model. - - [Illustration: Fig. 17. The Brennan gyroscopic mono-railway.--The - car is electrically driven, and its equilibrium is maintained by the - action of two gyroscopes, also electrically driven.] - -Mr Brennan's gyroscopic mono-railway was first shown, in a small size, -at a conversazione of the Royal Society in 1907. Full-sized cars were -constructed later, and one was seen at work during the Japan-British -Exhibition of 1910. The distinguishing feature of the vehicle is the -use of two gyroscopes (electrically driven), one horizontal and the -other vertical, to maintain the car upright on a single rail, even -when loaded unevenly and running at a fair speed round sharp curves. -From one point of view, the gyroscopic car is no more wonderful than -a spinning top, but the spectacle of a vehicle running steadily on a -single rail was so extraordinary that the interest of the whole world -was immediately aroused. Support was given to Mr Brennan's experiments -by the India Office and the Colonial Office, on the ground that a -railway which required only one rail, and was more or less independent -of both curves and gradients, would be of great value in districts -where the ordinary two-track railway might be both inconvenient and too -costly. One drawback to the arrangement is the necessity of fitting -each vehicle with gyroscopes, which are expensive and delicate pieces -of apparatus. But the ingenuity of the invention is so great that Mr -Brennan ought to reap the reward of seeing a gyroscopic railway in full -operation before long. - -The only electric mono-railway actually at work is the 'hanging -railway' at Elberfeld in Germany (Fig. 13). This railway is an -evolution from the system of 'telpherage' which was devised in the -very infancy of electric traction for the transport of goods. The root -idea is to make the overhead wire carrying the current the track rail -as well, the whole contrivance--rails and cars--being suspended from -girders or cables supported by a series of standards or bridges. At -Elberfeld the cars pass over streets and also over canals. There are -no signs, however, that the 'hanging railway' will have any imitators. -In appearance and in cost of construction and operation it does not -seem to have any conspicuous advantages over a double-track overhead -railway. The system of telpherage is therefore likely to be confined -to the carriage of goods from one part of a factory to another, and -(in the form of cable-ways) to the handling of materials in mines and -other extensive engineering works. For such purposes it is having an -increasingly extended application. - - [Illustration: Fig. 18. The 'Telpher' system of electrical locomotion - adapted to the transport of materials in a factory. The 'car' is - suspended from a girder and is operated by the driver in the same - way as an electric car. (From _Electrics_.)] - - - - - CHAPTER XVI - - THE FUTURE - - -Nothing irritates an electrical engineer more readily than the -repetition of the phrase, 'Electricity is in its infancy.' The words -have been used by countless mayors and aldermen while 'inaugurating' -tramway or electric lighting schemes; they have been echoed by -innumerable journalists who persist in maintaining a Jules-Verne -attitude towards the electrical industry. And what disturbs the -electrical engineer is not only the banality of the phrase but the use -of it as a comment upon the achievements to which he has devoted his -life. - -Nevertheless it will be admitted, from the rapid survey which we have -taken of electric traction, that the potentialities of electricity in -locomotion make an even stronger appeal than the actualities. Except in -one field--the tramway field--engineers have only touched the fringe of -possible developments in electric locomotion. - -Even in tramway work we may, if legislative conditions improve and -if current becomes much cheaper, see a considerable development in -passenger and also in agricultural lines. Meanwhile the trolley omnibus -offers a prospect of extension in electric road traction; and there -is a great deal yet to be done with petrol-electric vehicles and with -electric automobiles in certain classes of transport. - -The great field, however, lies in railway traction. There are 200 -miles of electric railway in the United Kingdom; and there are nearly -13,000 miles of steam railway. Not even the most sanguine electrical -missionary will believe that this difference can be materially altered -within the next decade, but there is ample ground for faith in the -steady increase of the electrical figure. If the advance of electric -traction on railways must be slow, it is because financial and not -engineering considerations govern the speed of conversion. No railway -company can take a step involving hundreds of thousands of pounds, and -a revolution in working methods, without prolonged consideration and -elaborate preparation. - -On roads, on tramways, and on railroads, the future lies with -electricity--wholly on railroads and tramways, perhaps not wholly on -roads. There is scope for it also at sea; and if our canals are worth -the cost of reconstruction on modern lines, electric haulage will -be used there on the model of the canal haulage installations which -exist here and there on the Continent. For marine work the advantages -of electricity have yet to be confirmed by practical experience; but -on land it has already proved that it supplies a means of locomotion -which is more efficient, cleaner and more attractive, and more closely -adapted to the needs and distribution of modern population than any -other. - -The fashion for devising Utopias is not so popular as it used to be, -but in every ideal world which is more than a spiritual vision, and -in every intelligent forecast of an advanced civilisation, universal -electric transport is taken for granted. Electrical engineers are ready -to prove that this standard element in Utopia is available at the -present day on the basis which is the ultimate justification of all -engineering projects in this workaday world--the basis of profit. - -Their confidence will be intensified when we approach the -'all-electric' age prophesied by Mr Ferranti in his Presidential -Address to the Institution of Electrical Engineers in 1910. Mr Ferranti -looks forward to a national scheme for the supply and distribution of -electric power. Under this scheme, the production of electricity would -be concentrated in one hundred huge power stations, using engines of -enormous capacity and acting as wholesale suppliers of electrical -energy to towns, railways, tramways, and factories. The price of -electricity would then be a fraction of what it is now; and all the -economies of electricity in action would be multiplied accordingly. -Technically, the scheme is quite feasible; and it could be realised -in the near future if capitalists and the Government could be brought -to appreciate the tremendous stimulus it would offer to industrial -activity and the effect it would have in conserving the power which is -latent in our coal measures. - - - - - INDEX - - - Acceleration, 23 _et seq._ - on electric railways, 107, 110 - - Accumulators, 70 - on air ships, 90 - on ships, 90 - - Aeroplanes, 90 - - Alternating current, 30, 115 - - Automixte (petrol-electric), 85 - - Automobiles (electric), 70 _et seq._ - advantages of, 80 - hiring of, 75 - in United States, 79 - - - Batteries (electric), 13 - - Behr, F. B., 131 - - Blackpool, 37 - - Bournemouth, 38 - - Braking, 67 - - Brennan, L., 132, 134 - - Brighton line electrification, 117 - - Broadbent, F., vii, 116 - - Brunel, 8, 11, 17 - - - Cab (electric), 78 - - City and South London Railway, 97 - - Conduit system, 28, 37, 126 - - Continuous current, 116 - - - District Railway, 103, 119 - - Durtnall, W. P., 88 - - Dynamo, 13 - reversibility of, 15, 67 - - - Elberfeld-Barmen Railway, 125, 135 - - Electric traction - advantages of, 19 _et seq._ - automobiles, 70 _et seq._ - backwardness of, 46 _et seq._ - on main line railways, 116, 122 - - - Faraday, 13 - - Ferranti, 140 - - Fischer (petrol-electric), 85 - - - Giant's Causeway, 93 - - Griffiths-Bedell (G-B.) system, 44 - - Gyroscopic railways, 132 - - - Hanging railway, 125, 135 - - Heilmann locomotive, 128 - - - Kearney, E. W. C., 133 - - - Launches (electric), 73 - - Light Railways Act, 58 - - Liverpool Overhead Railway, 97, 111 - - Locomotive (electric), 12, 97, 108 - Heilmann, 128 - turbo-electric, 129 - - London - electric cabs in, 79 - electric railways in, 97, 103 - tramways in, 39, 53 - - Lorain system, 44 - - Lyttelton, A., 119 - - - Marylebone, 81 - - Mavor, H., 88 - - Mersey railway, 97 - - Mono-railways, 131 _et seq._ - gyroscopic, 132 - - Motor (electric), 14 - - Multiple-unit system, 99, 108 - - - Omnibus (electric), 77 - petrol-electric, 83 - - Overhead system, 17, 128 - - - 'Paragon' system (ship propulsion), 87 - - Petrol-electric system, 82 _et seq._ - - Provisional Orders (Tramways), 48 - - - Railless traction (_see_ trolley omnibus) - - Railways - atmospheric, 7 - cheap power for, 113 - experimental electric, 16 - finance of, 100 - opposition to, 6 - pioneer electric, 92, 96 - rope, 7 - - Raworth, J. S., 68 - - Regenerative control, 67 - - - Series-parallel system, 32, 115 - - Ship propulsion, 88 - - Siemens, vii, 14, 16, 114 - - Signalling (automatic), 112 - - Single-phase system, 120 - - Starting torque, 23 (_see_ also acceleration) - - Stephenson, vii, 5, 9 - - Storage batteries, 70 _et seq._ - - 'Stud' system, 42 - - - Telpher system, 136 - - Third rail, 16 - - Three-phase system, 118 - - Torquay, 44 - - Trackless trolley (_see_ trolley omnibus) - - Trailers, 26 - - Tramcars - equipment of, 31 - - Tramroads - early, 4 - - Tramways - accumulators on, 20 - conduit, 28, 37, 126 - cost of, 53 - generating equipment for, 22 - inter-urban, 50 - legislation for, 47 - municipal, 49 - overhead system on, 17, 128 - statistics, 27, 28 - surface-contact, 28, 42 - - Tramways Act (1870), 95 - - Trolley omnibus, 56, 60 _et seq._ - in relation to tramways, 65 - - Trolley system 17, 29 _et seq._ - bow, 31 - - Tube railways, 97 - - Turbo-electric locomotive, 129 - - - Veto (tramway), 47, 51 - - - Waterfalls - electric power from, 94 - - Watt, vii - - Wheatstone, 14 - - Wolverhampton, 44 - - Workmen's fares, 53 - - - Yerkes, C. T., 104 - - - - - _Cambridge:_ - - PRINTED BY JOHN CLAY, M.A. - - AT THE UNIVERSITY PRESS - - - - - Transcriber's Note: - - - Italics are indicated by _underscores_. - - Bolds are indicated by =equal signs=. - - Small capitals have been rendered in full capitals. - - Footnote is placed to the end of chapter. - - A number of minor spelling errors have been corrected without note. - - - - - -End of Project Gutenberg's Electricity in Locomotion, by Adam Gowens Whyte - -*** END OF THIS PROJECT GUTENBERG EBOOK ELECTRICITY IN LOCOMOTION *** - -***** This file should be named 51242.txt or 51242.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/1/2/4/51242/ - -Produced by WebRover, Chris Curnow, Haragos Pal and the -Online Distributed Proofreading Team at http://www.pgdp.net -(This file was produced from images generously made -available by The Internet Archive) - - -Updated editions will replace the previous one--the old editions -will be renamed. - -Creating the works from public domain print editions means that no -one owns a United States copyright in these works, so the Foundation -(and you!) can copy and distribute it in the United States without -permission and without paying copyright royalties. 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