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diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..975c3b4 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #51242 (https://www.gutenberg.org/ebooks/51242) diff --git a/old/51242-8.txt b/old/51242-8.txt deleted file mode 100644 index d4d906f..0000000 --- a/old/51242-8.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: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK ELECTRICITY IN LOCOMOTION *** - - - - -Produced by WebRover, Chris Curnow, Haragos Pál 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 Ł80 to earn Ł100; an -electric tramway need spend only about Ł60. 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 Ł9500 -per mile, they have actually cost over Ł12,000 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 Ł200,000 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 Ł3,000,000, 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. 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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: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK ELECTRICITY IN LOCOMOTION *** - - - - -Produced by WebRover, Chris Curnow, Haragos Pál and the -Online Distributed Proofreading Team at http://www.pgdp.net -(This file was produced from images generously made -available by The Internet Archive) - - - - - - -</pre> - - - - - -<div class="figcenter" style="width: 70%" > -<img src="images/cover.jpg" alt="Cover" style="width: 70%" /> -</div> - - - - -<hr class="chap" /> - - - - -<p class="center"> -<big><big>The Cambridge Manuals of Science and -Literature</big></big></p> - -<h1>ELECTRICITY IN LOCOMOTION</h1> - - - - -<hr class="chap" /> - - - - - - -<p class="center"> -<big><big>CAMBRIDGE UNIVERSITY PRESS</big></big><br /> -<big><big>London: FETTER LANE, E.C.</big></big><br /> -<big>C. F. CLAY, <span class="smcap">Manager</span></big><br /></p> - - -<div class="figcenter" style="width: 30%" > -<img src="images/c.jpg" alt="image" style="width: 30%" /> -</div> - - -<p class="center"><br /> -Edinburgh: 100, PRINCES STREET<br /> -London: H. K. LEWIS, 136, GOWER STREET, W.C.<br /> -Berlin: A. ASHER AND CO.<br /> -Leipzig: F. A. BROCKHAUS<br /> -New York: G. P. PUTNAM'S SONS<br /> -Bombay and Calcutta: MACMILLAN AND CO., <span class="smcap">Ltd.</span><br /> -<br /> -<br /> -<i>All rights reserved</i><br /> -</p> - - - -<hr class="chap" /> - - - - -<p class="center"> -<big><big>ELECTRICITY IN</big></big><br /> -<big><big>LOCOMOTION</big></big><br /> -</p> - -<p class="p22"> -<big>AN ACCOUNT OF</big><br /> -<big>ITS MECHANISM,</big><br /> -<big>ITS ACHIEVEMENTS, AND</big><br /> -<big>ITS PROSPECTS</big></p> - -<p class="p04"> -BY<br /> -<br /> -ADAM GOWANS WHYTE, B.Sc.<br /> -<small>Editor of <i>Electrical Industries</i></small><br /> -<small>and <i>Electrics</i></small></p> - -<p class="p33"> -Cambridge:<br /> -at the University Press<br /> -1911 -</p> - - - -<hr class="chap" /> - - - -<p class="p33"> -<big>TO</big> -<br /><br /> -<big>EMILE GARCKE</big></p> - -<p class="pxx"><i>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.</i></p> - - - -<hr class="chap" /> - - - - - -<p><span class="pagenum"><a name="Page_v" id="Page_v">[Pg v]</a></span></p> - - - - -<h2>PREFACE</h2> - - -<p>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.</p> - -<p>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.</p> - -<p>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.</p> - - -<p><span class="pagenum"><a name="Page_vi" id="Page_vi">[Pg vi]</a></span></p> - - -<p>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.</p> - -<p>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.</p> - -<p>I have to acknowledge the kind assistance of -Mr. Frank Broadbent, M.I.E.E., in looking over the -proofs of this volume.</p> - -<p class="pxr"> -A. G. W.</p> - -<p class="px"> -<i>21 April 1911</i> -</p> - - - -<hr class="chap" /> - - -<h2>CONTENTS</h2> - - -<table class="toc" summary="Contents"> - -<tr> - <td class="tocnum"></td> - <td class="toctit"></td> - <td class="tocpag"><small>PAGE</small></td> -</tr><tr> - <td class="tocnum"></td> - <td class="toctit"><span class="smcap">Preface</span></td> - <td class="tocpag"><a href="#Page_v">v</a></td> -</tr><tr> - <td class="tocnum"><small>CHAP.</small></td> - <td class="toctit"></td> - <td class="tocpag"></td> -</tr><tr> - <td class="tocnum">I.</td> - <td class="toctit">The Wheel and the Public</td> - <td class="tocpag"><a href="#Page_1">1</a></td> -</tr><tr> - <td class="tocnum">II.</td> - <td class="toctit">Early Tramroads and Railways</td> - <td class="tocpag"><a href="#Page_4">4</a></td> -</tr><tr> - <td class="tocnum">III.</td> - <td class="toctit">The Birth of Electric Traction</td> - <td class="tocpag"><a href="#Page_12">12</a></td> -</tr><tr> - <td class="tocnum">IV.</td> - <td class="toctit"> The Essential Advantages of Electric Traction on Tramways</td> - <td class="tocpag"><a href="#Page_19">19</a></td> -</tr><tr> - <td class="tocnum">V.</td> - <td class="toctit">The Mechanism of an Electric Tramcar: the Overhead System</td> - <td class="tocpag"><a href="#Page_29">29</a></td> -</tr><tr> - <td class="tocnum">VI.</td> - <td class="toctit">Conduit and Surface-Contact Tramway Systems</td> - <td class="tocpag"><a href="#Page_37">37</a></td> -</tr><tr> - <td class="tocnum">VII.</td> - <td class="toctit">The Backwardness of Electric Traction in Great Britain</td> - <td class="tocpag"><a href="#Page_46">46</a></td> -</tr><tr> - <td class="tocnum">VIII.</td> - <td class="toctit">Electric Tramway Stagnation. The Trolley Omnibus</td> - <td class="tocpag"><a href="#Page_55">55</a></td> -</tr><tr> - <td class="tocnum">IX.</td> - <td class="toctit">Regenerative Control</td> - <td class="tocpag"><a href="#Page_67">67</a></td> -</tr><tr> - <td class="tocnum">X.</td> - <td class="toctit">Accumulator Electric Traction. The Electric Automobile</td> - <td class="tocpag"><a href="#Page_70">70</a></td> -</tr><tr> - <td class="tocnum">XI.</td> - <td class="toctit">Petrol-Electric Vehicles and main Marine Propulsion by Electricity</td> - <td class="tocpag"><a href="#Page_82">82</a></td> -</tr><tr> - <td class="tocnum">XII.</td> - <td class="toctit">The Pioneer Electric Railways</td> - <td class="tocpag"><a href="#Page_92">92</a></td> -</tr><tr> - <td class="tocnum">XIII.</td> - <td class="toctit">Electric Railways from the Engineering Point of View</td> - <td class="tocpag"><a href="#Page_107">107</a></td> -</tr><tr> - <td class="tocnum">XIV.</td> - <td class="toctit">Electric Traction on Main Line Railways</td> - <td class="tocpag"><a href="#Page_116">116</a></td> -</tr><tr> - <td class="tocnum">XV.</td> - <td class="toctit">Curiosities of Electric Traction</td> - <td class="tocpag"><a href="#Page_124">124</a></td> -</tr><tr> - <td class="tocnum">XVI.</td> - <td class="toctit">The Future</td> - <td class="tocpag"><a href="#Page_138">138</a></td> -</tr><tr> - <td class="tocnum"></td> - <td class="toctit"><span class="smcap">Index</span></td> - <td class="tocpag"><a href="#Page_142">142</a></td> -</tr> -</table> - - - -<hr class="chap" /> - - - -<p><span class="pagenum"><a name="Page_1" id="Page_1">[Pg 1]</a></span></p> - - - - -<h2>CHAPTER I<br /><br /> - -<small>THE WHEEL AND THE PUBLIC</small></h2> - - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_2" id="Page_2">[Pg 2]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_3" id="Page_3">[Pg 3]</a></span> -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.</p> - -<p>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.</p> - -<p>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.</p> - - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_4" id="Page_4">[Pg 4]</a></span></p> - - - - -<h2>CHAPTER II<br /><br /> - -<small>EARLY TRAMROADS AND RAILWAYS</small></h2> - - -<p>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_5" id="Page_5">[Pg 5]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_6" id="Page_6">[Pg 6]</a></span> -tramroad for the use of the public in general transport -by horse traction.</p> - -<p>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 -<i>Quarterly Review</i> 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.</p> - -<p>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<span class="pagenum"><a name="Page_7" id="Page_7">[Pg 7]</a></span> -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.</p> - -<p>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.</p> - -<p>These three modes were (1) stationary engines: -(2) locomotives: (3) the device known as the 'atmospheric -railway.'</p> - -<p>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<span class="pagenum"><a name="Page_8" id="Page_8">[Pg 8]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_9" id="Page_9">[Pg 9]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_10" id="Page_10">[Pg 10]</a></span> -weight of a rope, was superior to locomotive power, -on the following grounds:</p> - -<p>(<i>a</i>) A given amount of power may be supplied -by a stationary engine at a less cost than if supplied -by a locomotive.</p> - -<p>(<i>b</i>) 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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_11" id="Page_11">[Pg 11]</a></span> -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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_12" id="Page_12">[Pg 12]</a></span></p> - - - - -<h2>CHAPTER III<br /><br /> - -<small>THE BIRTH OF ELECTRIC TRACTION</small></h2> - - -<p>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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_13" id="Page_13">[Pg 13]</a></span>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.</p> - - - -<div class="figcenter" style="width: 80%" > -<img src="images/013.jpg" alt="Dynamo" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - - -<p>The essential step towards the commercial plane -was taken when an efficient means was devised for -transforming mechanical into electrical energy on a -<span class="pagenum"><a name="Page_14" id="Page_14">[Pg 14]</a></span>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.</p> - -<p>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.</p> - -<p>The simplicity of the arrangement is enhanced<span class="pagenum"><a name="Page_15" id="Page_15">[Pg 15]</a></span> -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.</p> - -<p>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 <i>driven</i> 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.</p> - -<p>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<span class="pagenum"><a name="Page_16" id="Page_16">[Pg 16]</a></span> -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.</p> - -<p>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.</p> - -<p><span class="pagenum"><a name="Page_17" id="Page_17">[Pg 17]</a></span></p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_18" id="Page_18">[Pg 18]</a></span> -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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_19" id="Page_19">[Pg 19]</a></span></p> - - - - -<h2>CHAPTER IV<br /><br /> - -<small>THE ESSENTIAL ADVANTAGES OF ELECTRIC -TRACTION ON TRAMWAYS</small></h2> - - -<p>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.</p> - -<p>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.</p> -<p><span class="pagenum"><a name="Page_20" id="Page_20">[Pg 20]</a></span></p> - - - -<div class="figcenter" style="width: 80%" > -<img src="images/020.jpg" alt="Tramway" style="width: 60%" /> -<div class="caption"> -<p class="pill">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.)</p> -</div> -</div> - - - -<p><span class="pagenum"><a name="Page_21" id="Page_21">[Pg 21]</a></span></p> -<p>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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>The whole of the power-producing plant for a -typical electric tramway system is concentrated at -<span class="pagenum"><a name="Page_22" id="Page_22">[Pg 22]</a></span>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.</p> - -<p>This advantage reduces the expenditure necessary<span class="pagenum"><a name="Page_23" id="Page_23">[Pg 23]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_24" id="Page_24">[Pg 24]</a></span> -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.</p> - -<p>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 <i>rapid</i> acceleration.</p> - -<p>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<span class="pagenum"><a name="Page_25" id="Page_25">[Pg 25]</a></span> -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.</p> - -<p>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.</p> - -<p>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,<span class="pagenum"><a name="Page_26" id="Page_26">[Pg 26]</a></span> -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.</p> - -<p>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.</p> - -<p>Finally, it falls to be noted that the power con<span class="pagenum"><a name="Page_27" id="Page_27">[Pg 27]</a></span>sumed -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.</p> - -<p>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<span class="pagenum"><a name="Page_28" id="Page_28">[Pg 28]</a></span> -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.</p> - -<p>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 Ł80 to -earn Ł100; an electric tramway need spend only -about Ł60. 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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_29" id="Page_29">[Pg 29]</a></span></p> - - - - -<h2>CHAPTER V<br /><br /> - -<small>THE MECHANISM OF AN ELECTRIC TRAMCAR: -THE OVERHEAD SYSTEM</small></h2> - - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_30" id="Page_30">[Pg 30]</a></span>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.</p> - -<p><span class="pagenum"><a name="Page_31" id="Page_31">[Pg 31]</a></span></p> - - - -<div class="figcenter" style="width: 80%" > -<img src="images/030.jpg" alt="Overhead system" style="width: 60%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - - - -<p>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_32" id="Page_32">[Pg 32]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_33" id="Page_33">[Pg 33]</a></span> -'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.</p> - -<p>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<span class="pagenum"><a name="Page_34" id="Page_34">[Pg 34]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_35" id="Page_35">[Pg 35]</a></span> -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.</p> - -<p>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.</p> - -<p><span class="pagenum"><a name="Page_36" id="Page_36">[Pg 36]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/036.jpg" alt="Pantograph" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.)</p> -</div> -</div> - - - -<hr class="chap" /> - - -<p><span class="pagenum"><a name="Page_37" id="Page_37">[Pg 37]</a></span></p> - - - -<h2>CHAPTER VI<br /><br /> - -<small>CONDUIT AND SURFACE-CONTACT TRAMWAY -SYSTEMS</small></h2> - - -<p>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.</p> - -<p>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.</p> - -<p>This was tried for the first time in Blackpool,<span class="pagenum"><a name="Page_38" id="Page_38">[Pg 38]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_39" id="Page_39">[Pg 39]</a></span> -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.</p> - -<p>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.</p> - -<p><span class="pagenum"><a name="Page_40" id="Page_40">[Pg 40]</a></span></p> - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_41" id="Page_41">[Pg 41]</a></span>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.</p> - - -<p><span class="pagenum"><a name="Page_42" id="Page_42">[Pg 42]</a></span></p> - - - -<div class="figcenter" style="width: 80%" > -<img src="images/041.jpg" alt="Conduit system" style="width: 60%" /> -<div class="caption"> -<p class="pill1">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.</p> - -<p class="pill2">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.)</p> -</div> -</div> - - - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_43" id="Page_43">[Pg 43]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_44" id="Page_44">[Pg 44]</a></span> -troubles the success of the surface-contact system -seemed as sensitive as the system itself.</p> - -<p>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.</p> - -<p>The results with the 'G-B.' system at Lincoln<span class="pagenum"><a name="Page_45" id="Page_45">[Pg 45]</a></span> -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.</p> - -<p>The upshot of the contest between the three -systems has, therefore, been the survival of the one -which was most despised at the outset.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_46" id="Page_46">[Pg 46]</a></span></p> - - - - -<h2>CHAPTER VII<br /><br /> - -<small>THE BACKWARDNESS OF ELECTRIC TRACTION -IN GREAT BRITAIN</small></h2> - - -<p>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.</p> - -<p>It is not strictly accurate to say that electric -tramway <i>enterprise</i> 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<span class="pagenum"><a name="Page_47" id="Page_47">[Pg 47]</a></span> -the altered conditions brought about by the use of -electricity.</p> - -<p>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.</p> - -<p><span class="pagenum"><a name="Page_48" id="Page_48">[Pg 48]</a></span></p> - -<p>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_49" id="Page_49">[Pg 49]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_50" id="Page_50">[Pg 50]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_51" id="Page_51">[Pg 51]</a></span> -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.</p> - -<p>One effect of this state of affairs was delay. The -preliminary negotiations with local authorities—the<span class="pagenum"><a name="Page_52" id="Page_52">[Pg 52]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_53" id="Page_53">[Pg 53]</a></span> -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 Ł9500 per mile, they have actually cost -over Ł12,000 per mile.</p> - -<p>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<span class="pagenum"><a name="Page_54" id="Page_54">[Pg 54]</a></span> -County Council recently stated that never a day -passes without some appeal for concessions in tramway -fares.</p> - -<p>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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_55" id="Page_55">[Pg 55]</a></span></p> - - - - -<h2>CHAPTER VIII<br /><br /> - -<small>ELECTRIC TRAMWAY STAGNATION. -THE TROLLEY OMNIBUS</small></h2> - - -<p>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 Ł200,000 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.</p> - -<p>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.</p> - - -<p><span class="pagenum"><a name="Page_56" id="Page_56">[Pg 56]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/056.jpg" alt="Photograph of an electric trolley omnibus" style="width: 60%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - -<p><span class="pagenum"><a name="Page_57" id="Page_57">[Pg 57]</a></span></p> - - - -<p>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 -<span class="pagenum"><a name="Page_58" id="Page_58">[Pg 58]</a></span>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.</p> - -<p>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.</p> - -<p>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,<span class="pagenum"><a name="Page_59" id="Page_59">[Pg 59]</a></span> -if confirmed, thus secured the validity of a Private -Act of Parliament.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_60" id="Page_60">[Pg 60]</a></span> -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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>The trolley omnibus is a hybrid between the -trolley tramcar and the omnibus. It is akin to the<span class="pagenum"><a name="Page_61" id="Page_61">[Pg 61]</a></span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_62" id="Page_62">[Pg 62]</a></span>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.</p> - -<p>The other side of the picture is shown when we -come to look into the costs of working.</p> - -<p>No matter how good the road surface may be or<span class="pagenum"><a name="Page_63" id="Page_63">[Pg 63]</a></span> -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<i>d.</i> or 2<i>d.</i> 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.</p> - -<p>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<span class="pagenum"><a name="Page_64" id="Page_64">[Pg 64]</a></span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_65" id="Page_65">[Pg 65]</a></span>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.</p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/065.jpg" alt="The 'auto-trolley' system" style="width: 70%" /> -<div class="caption"> -<p class="pill">Fig. 7. The 'auto-trolley' system of electric traction applied to the -haulage of goods in a German quarry. (From <i>Electrical Industries</i>.)</p> -</div> -</div> - - - -<p>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 -<span class="pagenum"><a name="Page_66" id="Page_66">[Pg 66]</a></span>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.'</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_67" id="Page_67">[Pg 67]</a></span></p> - - - -<h2>CHAPTER IX<br /><br /> - -<small>REGENERATIVE CONTROL</small></h2> - - -<p>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.'</p> - -<p>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<span class="pagenum"><a name="Page_68" id="Page_68">[Pg 68]</a></span> -'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.</p> - -<p>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.</p> - -<p>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,<span class="pagenum"><a name="Page_69" id="Page_69">[Pg 69]</a></span> -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.</p> - -<p>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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_70" id="Page_70">[Pg 70]</a></span></p> - - - - -<h2>CHAPTER X<br /><br /> - -<small>ACCUMULATOR ELECTRIC TRACTION.<br /> -THE ELECTRIC AUTOMOBILE</small></h2> - - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_71" id="Page_71">[Pg 71]</a></span>cent. That is to say, there is a loss of about 20 per -cent. in the process of conversion and re-conversion.</p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/071.jpg" alt="Electric automobile" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.)</p> -</div> -</div> - - - -<p>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 -<span class="pagenum"><a name="Page_72" id="Page_72">[Pg 72]</a></span>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_73" id="Page_73">[Pg 73]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_74" id="Page_74">[Pg 74]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_75" id="Page_75">[Pg 75]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_76" id="Page_76">[Pg 76]</a></span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_77" id="Page_77">[Pg 77]</a></span>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_78" id="Page_78">[Pg 78]</a></span> -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.</p> - -<p>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.</p> - -<p>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; -<span class="pagenum"><a name="Page_79" id="Page_79">[Pg 79]</a></span>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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>The vans belonging to a large store all start from -a certain point and return to it after journeys of<span class="pagenum"><a name="Page_80" id="Page_80">[Pg 80]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_81" id="Page_81">[Pg 81]</a></span> -8<i>d.</i> to 2<i>s.</i> 6<i>d.</i> 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<i>d.</i> 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.</p> - -<p>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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_82" id="Page_82">[Pg 82]</a></span></p> - - - - -<h2>CHAPTER XI<br /><br /> - -<small>PETROL-ELECTRIC VEHICLES AND MAIN MARINE -PROPULSION BY ELECTRICITY</small></h2> - - -<p>Between the petrol-driven vehicle and the electric -automobile there is an interesting series of links -provided by 'petrol-electric' systems.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_83" id="Page_83">[Pg 83]</a></span>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.</p> - - -<p><span class="pagenum"><a name="Page_84" id="Page_84">[Pg 84]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/083.jpg" alt="Petrol-electric motor omnibus" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - - -<p><span class="pagenum"><a name="Page_85" id="Page_85">[Pg 85]</a></span></p> - - -<p>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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_86" id="Page_86">[Pg 86]</a></span> -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.</p> - -<p>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.</p> - -<p>The underlying idea of the petrol-electric system -has, however, been suggested for marine propulsion -with a somewhat better prospect of success.</p> - -<p>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.</p> - - -<p><span class="pagenum"><a name="Page_87" id="Page_87">[Pg 87]</a></span></p> - -<div class="figcenter" style="width: 80%" > -<img src="images/087.jpg" alt="Steamship with 'Paragon' system" style="width: 80%" /> -<div class="caption"> -<p class="pill">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 -<i>The Electrician</i>.)</p> -</div> -</div> - - - -<p><span class="pagenum"><a name="Page_88" id="Page_88">[Pg 88]</a></span></p> - - - -<p>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.</p> - -<p>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.</p> - -<p>Moreover, the electric system can be so arranged -that the control gear may be operated from the<span class="pagenum"><a name="Page_89" id="Page_89">[Pg 89]</a></span> -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.</p> - -<p>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.</p> - -<p>It is hardly necessary, except as a matter of -curiosity, to refer to the suggestions made, from time<span class="pagenum"><a name="Page_90" id="Page_90">[Pg 90]</a></span> -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.</p> - -<p>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.</p> - -<p>One inventor has, I believe, suggested a means -of direct electrical propulsion for aeroplanes, the<span class="pagenum"><a name="Page_91" id="Page_91">[Pg 91]</a></span> -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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_92" id="Page_92">[Pg 92]</a></span></p> - - - - -<h2>CHAPTER XII<br /><br /> - -<small>THE PIONEER ELECTRIC RAILWAYS</small></h2> - - -<p>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.</p> - -<p>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.</p> - -<p><span class="pagenum"><a name="Page_93" id="Page_93">[Pg 93]</a></span></p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_94" id="Page_94">[Pg 94]</a></span> -of electrical development in Great Britain, not to -legislative conditions, but to the lack of large -waterfalls.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_95" id="Page_95">[Pg 95]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_96" id="Page_96">[Pg 96]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_97" id="Page_97">[Pg 97]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_98" id="Page_98">[Pg 98]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_99" id="Page_99">[Pg 99]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_100" id="Page_100">[Pg 100]</a></span> -suburban or similar inter-urban traffic has been -separable from the main line traffic.</p> - -<p>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.</p> - -<p>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, -<span class="pagenum"><a name="Page_101" id="Page_101">[Pg 101]</a></span>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_102" id="Page_102">[Pg 102]</a></span> -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.</p> - -<p>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.</p> - -<p>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.</p> - - -<p><span class="pagenum"><a name="Page_103" id="Page_103">[Pg 103]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/103.jpg" alt="Electric train" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - -<p><span class="pagenum"><a name="Page_104" id="Page_104">[Pg 104]</a></span></p> - - - - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_105" id="Page_105">[Pg 105]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_106" id="Page_106">[Pg 106]</a></span> -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.</p> - -<p>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.</p> - -<p>The engineering aspect of these changes has now -to be considered.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_107" id="Page_107">[Pg 107]</a></span></p> - - - - -<h2>CHAPTER XIII<br /><br /> - -<small>ELECTRIC RAILWAYS FROM THE ENGINEERING -POINT OF VIEW</small></h2> - - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_108" id="Page_108">[Pg 108]</a></span> -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.</p> - -<p>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.</p> - -<p>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.</p> - -<p><span class="pagenum"><a name="Page_109" id="Page_109">[Pg 109]</a></span></p> - -<p>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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>The adjustment of the length of trains to the -fluctuations of the service is made easier by the<span class="pagenum"><a name="Page_110" id="Page_110">[Pg 110]</a></span> -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.</p> - -<p>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.</p> - -<p>On the District Railway the rate of acceleration<span class="pagenum"><a name="Page_111" id="Page_111">[Pg 111]</a></span> -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.</p> - -<p>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<span class="pagenum"><a name="Page_112" id="Page_112">[Pg 112]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_113" id="Page_113">[Pg 113]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_114" id="Page_114">[Pg 114]</a></span> -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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>As regards the motor equipment on the cars,<span class="pagenum"><a name="Page_115" id="Page_115">[Pg 115]</a></span> -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.</p> - -<p>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.</p> - -<p>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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_116" id="Page_116">[Pg 116]</a></span></p> - - - - -<h2>CHAPTER XIV<br /><br /> - -<small>ELECTRIC TRACTION ON MAIN LINE RAILWAYS</small></h2> - - -<p>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.</p> - -<p>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<a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">[1]</a>.</p> - - - -<p><span class="pagenum"><a name="Page_117" id="Page_117">[Pg 117]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/117.jpg" alt="Photograph of a train" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - - -<p><span class="pagenum"><a name="Page_118" id="Page_118">[Pg 118]</a></span></p> - - -<p>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_119" id="Page_119">[Pg 119]</a></span> -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.</p> - -<p>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.</p> - -<p>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;<span class="pagenum"><a name="Page_120" id="Page_120">[Pg 120]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_121" id="Page_121">[Pg 121]</a></span> -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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_122" id="Page_122">[Pg 122]</a></span> -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.</p> - -<p>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.</p> - -<p>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.</p> - -<p>The adoption of electric traction on such a route -<span class="pagenum"><a name="Page_123" id="Page_123">[Pg 123]</a></span>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.</p> - -<hr class="r5" /> - -<div class="footnote"> - -<p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">[1]</span></a> An admirable explanation of alternating currents will be found -in Mr Frank Broadbent's <i>Chats on Electricity</i>. (Werner Laurie, 1910.)</p></div> - - -<hr class="chap" /> - - -<p><span class="pagenum"><a name="Page_124" id="Page_124">[Pg 124]</a></span></p> - - - -<h2>CHAPTER XV<br /><br /> - -<small>CURIOSITIES OF ELECTRIC TRACTION</small></h2> - - -<p>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.</p> - -<p>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.</p> - - -<p><span class="pagenum"><a name="Page_125" id="Page_125">[Pg 125]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/125.jpg" alt="Elberfeld-Barmen hanging electric railway" style="width: 80%" /> -<div class="caption"> -<p class="pill">Fig. 13. Illustration of Elberfeld-Barmen hanging electric railway. From <i>The Electrical -Industry</i> (Books on Business), published by Messrs Methuen.</p> -</div> -</div> - - - -<p><span class="pagenum"><a name="Page_126" id="Page_126">[Pg 126]</a></span></p> - - -<p>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.</p> - -<p>More plausible forms of super-ingenuity have -been exercised in connection with established modes -of electric traction.</p> - -<p>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.</p> - - - -<p><span class="pagenum"><a name="Page_127" id="Page_127">[Pg 127]</a></span></p> - - - -<div class="figcenter" style="width: 80%" > -<img src="images/127.jpg" alt="Heilmann electric locomotive" style="width: 80%" /> -<div class="caption"> -<p class="pill">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 <a href="#Page_130">p. 130</a> and illustrated in <a href="#Page_129">Fig. 15.</a></p> -</div> -</div> - - - -<p><span class="pagenum"><a name="Page_128" id="Page_128">[Pg 128]</a></span></p> - - - -<p>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.</p> - -<p>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.</p> - -<p>One of the best known of electrical freaks—the -Heilmann locomotive (<a href="#Page_127">Fig. 14</a>)—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.</p> - - - -<p><span class="pagenum"><a name="Page_129" id="Page_129">[Pg 129]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/129.jpg" alt="Electro-turbo-locomotive" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - - - -<p><span class="pagenum"><a name="Page_130" id="Page_130">[Pg 130]</a></span></p> - - - -<p>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.</p> - -<p>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 (<a href="#Page_129">Fig. 15</a>). 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.</p> - - -<p><span class="pagenum"><a name="Page_131" id="Page_131">[Pg 131]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/131.jpg" alt="Behr electric mono-rail car" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - - -<p><span class="pagenum"><a name="Page_132" id="Page_132">[Pg 132]</a></span></p> - - - -<p>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.</p> - -<p>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 Ł3,000,000, but the public response to the first -invitation was so small that the scheme was abandoned.</p> - -<p><span class="pagenum"><a name="Page_133" id="Page_133">[Pg 133]</a></span></p> - -<p>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 <b>V</b>, 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.</p> - -<p>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.</p> - - -<p><span class="pagenum"><a name="Page_134" id="Page_134">[Pg 134]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/134.jpg" alt="The Brennan gyroscopic mono-railway" style="width: 80%" /> -<div class="caption"> -<p class="pill">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.</p> -</div> -</div> - - -<p><span class="pagenum"><a name="Page_135" id="Page_135">[Pg 135]</a></span></p> - - - -<p>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.</p> - - -<p><span class="pagenum"><a name="Page_136" id="Page_136">[Pg 136]</a></span></p> - - -<div class="figcenter" style="width: 80%" > -<img src="images/136.jpg" alt="'Telpher' system" style="width: 70%" /> -<div class="caption"> -<p class="pill">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 <i>Electrics</i>.)</p> -</div> -</div> - - -<p>The only electric mono-railway actually at work is -the 'hanging railway' at Elberfeld in Germany (<a href="#Page_125">Fig. -13</a>). 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 -<span class="pagenum"><a name="Page_137" id="Page_137">[Pg 137]</a></span>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.</p> - - - -<hr class="chap" /> - - - -<p><span class="pagenum"><a name="Page_138" id="Page_138">[Pg 138]</a></span></p> - - - -<h2>CHAPTER XVI<br /><br /> - -<small>THE FUTURE</small></h2> - - -<p>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.</p> - -<p>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.</p> - -<p><span class="pagenum"><a name="Page_139" id="Page_139">[Pg 139]</a></span></p> - -<p>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.</p> - -<p>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.</p> - -<p>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<span class="pagenum"><a name="Page_140" id="Page_140">[Pg 140]</a></span> -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.</p> - -<p>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.</p> - -<p>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 -<span class="pagenum"><a name="Page_141" id="Page_141">[Pg 141]</a></span>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.</p> - - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_142" id="Page_142">[Pg 142]</a></span></p> - - - - - -<h2>INDEX</h2> - - -<ul> -<li><span><a name="acc"></a></span>Acceleration, <a href="#Page_23">23</a> <i>et seq.</i> - <ul> - <li>on electric railways, <a href="#Page_107">107</a>, <a href="#Page_110">110</a></li> - </ul> -</li> - -<li>Accumulators, <a href="#Page_70">70</a> - <ul> - <li>on air ships, <a href="#Page_90">90</a></li> - <li>on ships, <a href="#Page_90">90</a></li> - </ul></li> -<li>Aeroplanes, <a href="#Page_90">90</a></li> - -<li>Alternating current, <a href="#Page_30">30</a>, <a href="#Page_115">115</a></li> - -<li>Automixte (petrol-electric), <a href="#Page_85">85</a></li> - -<li>Automobiles (electric), <a href="#Page_70">70</a> <i>et seq.</i> - <ul> - <li>advantages of, <a href="#Page_80">80</a></li> - <li>hiring of, <a href="#Page_75">75</a></li> - <li>in United States, <a href="#Page_79">79</a></li> - </ul></li> -</ul> - - -<ul> -<li>Batteries (electric), <a href="#Page_13">13</a></li> - -<li>Behr, F. B., <a href="#Page_131">131</a></li> - -<li>Blackpool, <a href="#Page_37">37</a></li> - -<li>Bournemouth, <a href="#Page_38">38</a></li> - -<li>Braking, <a href="#Page_67">67</a></li> - -<li>Brennan, L., <a href="#Page_132">132</a>, <a href="#Page_134">134</a></li> - -<li>Brighton line electrification, <a href="#Page_117">117</a></li> - -<li>Broadbent, F., <a href="#Page_vi">vi</a>, <a href="#Page_116">116</a></li> - -<li>Brunel, <a href="#Page_8">8</a>, <a href="#Page_11">11</a>, <a href="#Page_17">17</a></li> -</ul> - - -<ul> -<li>Cab (electric), <a href="#Page_78">78</a></li> - -<li>City and South London Railway, <a href="#Page_97">97</a></li> - -<li>Conduit system, <a href="#Page_28">28</a>, <a href="#Page_37">37</a>, <a href="#Page_126">126</a></li> - -<li>Continuous current, <a href="#Page_116">116</a></li> -</ul> - - -<ul> -<li>District Railway, <a href="#Page_103">103</a>, <a href="#Page_119">119</a></li> - -<li>Durtnall, W. P., <a href="#Page_88">88</a></li> - -<li>Dynamo, <a href="#Page_13">13</a> - <ul> - <li>reversibility of, <a href="#Page_15">15</a>, <a href="#Page_67">67</a></li> - </ul></li> -</ul> - - -<ul> -<li>Elberfeld-Barmen Railway, <a href="#Page_125">125</a>, <a href="#Page_135">135</a></li> - -<li>Electric traction - <ul> - <li>advantages of, <a href="#Page_19">19</a> <i>et seq.</i></li> - <li>automobiles, <a href="#Page_70">70</a> <i>et seq.</i></li> - <li>backwardness of, <a href="#Page_46">46</a> <i>et seq.</i></li> - <li>on main line railways, <a href="#Page_116">116</a>, <a href="#Page_122">122</a></li> - </ul></li> -</ul> - - -<ul> -<li>Faraday, <a href="#Page_13">13</a></li> - -<li>Ferranti, <a href="#Page_140">140</a></li> - -<li>Fischer (petrol-electric), <a href="#Page_85">85</a></li> -</ul> - - -<ul> -<li>Giant's Causeway, <a href="#Page_93">93</a></li> - -<li>Griffiths-Bedell (G-B.) system, <a href="#Page_44">44</a></li> - -<li>Gyroscopic railways, <a href="#Page_132">132</a></li> -</ul> - - -<ul> -<li>Hanging railway, <a href="#Page_125">125</a>, <a href="#Page_135">135</a></li> - -<li>Heilmann locomotive, <a href="#Page_128">128</a></li> -</ul> - - -<ul> -<li>Kearney, E. W. C., <a href="#Page_133">133</a></li> -</ul> - - -<ul> -<li>Launches (electric), <a href="#Page_73">73</a></li> - -<li>Light Railways Act, <a href="#Page_58">58</a></li> - -<li>Liverpool Overhead Railway, <a href="#Page_97">97</a>, <a href="#Page_111">111</a></li> - -<li>Locomotive (electric), <a href="#Page_12">12</a>, <a href="#Page_97">97</a>, <a href="#Page_108">108</a> - <ul> - <li>Heilmann, <a href="#Page_128">128</a></li> - <li>turbo-electric, <a href="#Page_129">129</a></li> - </ul></li> - -<li>London - <ul> - <li>electric cabs in, <a href="#Page_79">79</a></li> - <li>electric railways in, <a href="#Page_97">97</a>, <a href="#Page_103">103</a></li> - <li>tramways in, <a href="#Page_39">39</a>, <a href="#Page_53">53</a></li> - </ul></li> - -<li>Lorain system, <a href="#Page_44">44</a></li> - -<li>Lyttelton, A., <a href="#Page_119">119</a></li> -</ul> - - - -<ul> -<li>Marylebone, <a href="#Page_81">81</a></li> - -<li>Mavor, H., <a href="#Page_88">88</a></li> - -<li>Mersey railway, <a href="#Page_97">97</a></li> - -<li>Mono-railways, <a href="#Page_131">131</a> <i>et seq.</i> - <ul> - <li>gyroscopic, <a href="#Page_132">132</a></li> - </ul></li> - -<li>Motor (electric), <a href="#Page_14">14</a></li> - -<li>Multiple-unit system, <a href="#Page_99">99</a>, <a href="#Page_108">108</a></li> -</ul> - - -<ul> -<li>Omnibus (electric), <a href="#Page_77">77</a> - <ul> - <li>petrol-electric, <a href="#Page_83">83</a></li> - </ul></li> - -<li>Overhead system, <a href="#Page_17">17</a>, <a href="#Page_128">128</a></li> -</ul> - - -<ul> -<li>'Paragon' system (ship propulsion), <a href="#Page_87">87</a></li> - -<li>Petrol-electric system, <a href="#Page_82">82</a> <i>et seq.</i></li> - -<li>Provisional Orders (Tramways), <a href="#Page_48">48</a></li> -</ul> - - -<ul> -<li>Railless traction (<i>see</i> <a href="#trol">trolley omnibus</a>)</li> - -<li>Railways - <ul> - <li>atmospheric, <a href="#Page_7">7</a></li> - <li>cheap power for, <a href="#Page_113">113</a></li> - <li>experimental electric, <a href="#Page_16">16</a></li> - <li>finance of, <a href="#Page_100">100</a></li> - <li>opposition to, <a href="#Page_6">6</a></li> - <li>pioneer electric, <a href="#Page_92">92</a>, <a href="#Page_96">96</a></li> - <li>rope, <a href="#Page_7">7</a></li> - </ul></li> - -<li>Raworth, J. S., <a href="#Page_68">68</a></li> - -<li>Regenerative control, <a href="#Page_67">67</a></li> -</ul> - - -<ul> -<li>Series-parallel system, <a href="#Page_32">32</a>, <a href="#Page_115">115</a></li> - -<li>Ship propulsion, <a href="#Page_88">88</a></li> - -<li>Siemens, <a href="#Page_vi">vi</a>, <a href="#Page_14">14</a>, <a href="#Page_16">16</a>, <a href="#Page_114">114</a></li> - -<li>Signalling (automatic), <a href="#Page_112">112</a></li> - -<li>Single-phase system, <a href="#Page_120">120</a></li> - -<li>Starting torque, <a href="#Page_23">23</a> (<i>see</i> also <a href="#acc">acceleration</a>)</li> - -<li>Stephenson, <a href="#Page_vi">vi</a>, <a href="#Page_5">5</a>, <a href="#Page_9">9</a></li> -<li>Storage batteries, <a href="#Page_70">70</a> <i>et seq.</i></li> -<li>'Stud' system, <a href="#Page_42">42</a></li> -</ul> - - -<ul> -<li>Telpher system, <a href="#Page_136">136</a></li> - -<li>Third rail, <a href="#Page_16">16</a></li> - -<li>Three-phase system, <a href="#Page_118">118</a></li> - -<li>Torquay, <a href="#Page_44">44</a></li> - -<li>Trackless trolley (<i>see</i> <a href="#trol">trolley omnibus</a>)</li> - -<li>Trailers, <a href="#Page_26">26</a></li> - -<li>Tramcars - <ul> - <li>equipment of, <a href="#Page_31">31</a></li> - </ul></li> - -<li>Tramroads - <ul> - <li>early, <a href="#Page_4">4</a></li> - </ul></li> - -<li>Tramways - <ul> - <li>accumulators on, <a href="#Page_20">20</a></li> - <li>conduit, <a href="#Page_28">28</a>, <a href="#Page_37">37</a>, <a href="#Page_126">126</a></li> - <li>cost of, <a href="#Page_53">53</a></li> - <li>generating equipment for, <a href="#Page_22">22</a></li> - <li>inter-urban, <a href="#Page_50">50</a></li> - <li>legislation for, <a href="#Page_47">47</a></li> - <li>municipal, <a href="#Page_49">49</a></li> - <li>overhead system on, <a href="#Page_17">17</a>, <a href="#Page_128">128</a></li> - <li>statistics, <a href="#Page_27">27</a>, <a href="#Page_28">28</a></li> - <li>surface-contact, <a href="#Page_28">28</a>, <a href="#Page_42">42</a></li> - </ul></li> - -<li>Tramways Act (1870), <a href="#Page_95">95</a></li> - -<li><span><a name="trol"></a></span>Trolley omnibus, <a href="#Page_56">56</a>, <a href="#Page_60">60</a> <i>et seq.</i> - <ul> - <li>in relation to tramways, <a href="#Page_65">65</a></li> - </ul></li> - -<li>Trolley system, <a href="#Page_17">17</a>, <a href="#Page_29">29</a> <i>et seq.</i> - <ul> - <li>bow, <a href="#Page_31">31</a></li> - </ul></li> -<li>Tube railways, <a href="#Page_97">97</a></li> - -<li>Turbo-electric locomotive, <a href="#Page_129">129</a></li> -</ul> - - -<ul> -<li>Veto (tramway), <a href="#Page_47">47</a>, <a href="#Page_51">51</a></li> -</ul> - - -<ul> -<li>Waterfalls - <ul> - <li>electric power from, <a href="#Page_94">94</a></li> - </ul></li> - -<li>Watt, <a href="#Page_vi">vi</a></li> - -<li>Wheatstone, <a href="#Page_14">14</a></li> - -<li>Wolverhampton, <a href="#Page_44">44</a></li> - -<li>Workmen's fares, <a href="#Page_53">53</a></li> -</ul> - - -<ul> -<li>Yerkes, C. T., <a href="#Page_104">104</a></li> -</ul> - - - - -<hr class="chap" /> - -<p class="p33"> -<i><big><big><b>Cambridge:</b></big></big></i><br /> -<br /> -PRINTED BY JOHN CLAY, M.A.<br /> -<br /> -<big>AT THE UNIVERSITY PRESS</big><br /> -</p> - - - - - - - - -<pre> - - - - - -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-h.htm or 51242-h.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 Pál 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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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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