,the ,cambridge ,manuals of ,science and ,literature ,,electricity ,,in ,,locomotion ,,cambridge ,,university ,,press ,london3 ,,fetter ,,lane1 ,e4,c4 ,c4 ,f4 ,,clay1 ,,manager ,illustration ,edinburgh3 #ajj1 ,,princes ,,street ,london3 ,h4 ,k4 ,,lewis1 #acf1 ,,gower ,,street1 ,w4,c4 ,berlin3 ,a4 ,,asher ,,and ,,co4 ,leipzig3 ,f4 ,a4 ,,brockhaus ,new ,york3 ,g4 ,p4 ,,putnam',s ,,sons ,bombay and ,calcutta3 ,,macmillan ,,and ,,co41 ,,ltd4 ,all rights reserved ,,electricity ,,in ,,locomotion ,,an ,,account ,,of ,,its ,,mechanism1 ,,its ,,achievements1 ,,and ,,its ,,prospects ,,by ,,adam ,,gowans ,,whyte1 ,b4,sc4 ,editor of ,electrical ,industries and ,electrics ,cambridge3 at the ,university ,press #aiaa ,,to ,,emile ,,garcke ,with the exception of the coat of arms at the foot1 the design on the title page is a reproduction of one used by the earliest known ,cambridge printer1 ,john ,siberch1 #aeba4 ,,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 locomotion4 ,some of the aspects of electric traction are highly technical2 others are purely financial4 ,it is impossible to understand the achievements and possibilities of electricity in locomotion without a certain amount of discussion of both these points of view2 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 rail4 ,the hopes of electrical conquest extend1 indeed1 to locomotion on the sea and in the air as well as on the land4 ,at the root of these hopes there lies a firm faith in the superior economies and flexibility of electricity as a mode of motion4 ,in the explanations which are given of electric tramways1 electric railways1 electric automobiles1 electric propulsion on ships1 and the other phases of electric traction1 nothing but the most elementary knowledge of electricity is presupposed4 ,a certain amount of technical description is unavoidable1 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 adoption4 ,anyone who glances over the history of electric traction will be struck by the absence of outstanding names4 ,there is no man who occupies the same position in the sphere of electric locomotion as ,watt does in the world of steam1 or ,stephenson in the world of railways4 ,as a pioneer1 ,dr4 ,wernher von ,siemens perhaps deserves more honour than any other4 ,but the leading ideas embodied in electric traction systems were contributed by engineers who worked in the general field of electrical engineering2 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 world4 ,nevertheless1 ,i hope the story as told briefly in the following chapters will not be found devoid of human interest4 ,it has the advantage1 at any rate1 of the attraction which anything pertaining to electricity holds for all sections of the public4 ,this attraction deepens upon closer acquaintance with the mechanism and the history of electricity in action2 and if any of the descriptions and forecasts are found to be prejudiced in favour of a single instrument of locomotion1 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 man4 ,i have to acknowledge the kind assistance of ,mr4 ,frank ,broadbent1 ,m4,i4,e4,e41 in looking over the proofs of this volume4 ,a4 ,g4 ,w4 #ba ,april #aiaa ,,contents ,,page ,,preface vi ,,chap4 ,i4 ,the ,wheel and the ,public #a ,,ii4 ,early ,tramroads and ,railways #d ,,iii4 ,the ,birth of ,electric ,traction #ab ,,iv4 ,the ,essential ,advantages of ,electric ,traction on ,tramways #ai ,v4 ,the ,mechanism of an ,electric ,tramcar3 the ,overhead ,system #bi ,,vi4 ,conduit and ,surface-,contact ,tramway ,systems #cg ,,vii4 ,the ,backwardness of ,electric ,traction in ,great ,britain #df ,,viii4 ,electric ,tramway ,stagnation4 ,the ,trolley ,omnibus #ee ,,ix4 ,regenerative ,control #fg ,x4 ,accumulator ,electric ,traction4 ,the ,electric ,automobile #gj ,,xi4 ,petrol-,electric ,vehicles and main ,marine ,propulsion by ,electricity #hb ,,xii4 ,the ,pioneer ,electric ,railways #ib ,,xiii4 ,electric ,railways from the ,engineering ,point of ,view #ajg ,,xiv4 ,electric ,traction on ,main ,line ,railways #aaf ,,xv4 ,curiosities of ,electric ,traction #abd ,,xvi4 ,the ,future #ach ,,index #adb ,,chapter ,i ,,the ,,wheel ,,and ,,the ,,public ,one of the greatest of unknown men of genius was the inventor of the wheel4 ,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 dragged4 ,but1 whatever the origin of the wheel and axle1 the combination was so admirable that it remained unchanged in its essential features for centuries and still forms the primary element in locomotion4 ,some of the earliest forms of vehicle can be found co-existing with the very latest4 ,in ,oporto1 for instance1 there are electric tramways1 but there are also ox wagons which seem to belong to the childhood of the world4 ,the wheels are rigidly fixed to rotating axles 7the oldest known arrangement7 and the supports of both the front and the back axles are rigidly fixed to the wagon4 ,the result is that the vehicle cannot 'steer' and must be dragged round corners4 ,some time ago the authorities1 realising at last that this dragging was ruinous to the road surfaces1 made a regulation that all wagons should have their front axles pivoted4 ,this attempt at improvement caused more agitation than the ,revolution itself4 ,the owners of wagons argued--with perfect justice--that the rigid wagon had served for innumerable generations2 and they refused1 in the face of fines1 to make the change4 ,their resistance was so general and so dogged that the law became a dead letter1 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 heads4 ,this example of conservatism1 though extreme1 is characteristic of the attitude of the general public towards innovations in locomotion4 ,until mechanical power came to be used1 there was--for many centuries--nothing which could be described as a radical innovation in transport4 ,roads were multiplied and improved2 some advance was made in the design and construction of carriages2 and the organisation of posting and stage-coach services was developed4 ,but little more was done4 ,compared with these superficial changes1 the idea of using steam power on the highway or on a railroad was so drastic a change that it roused tremendous opposition4 ,the railway companies fought this opposition and overcame it1 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 roads4 ,in a similar way horse tramways were violently attacked2 and their conversion to electric traction was opposed by a determined minority in every town4 ,more recently1 there was a vigorous agitation against the substitution of motor omnibuses for horse omnibuses in ,london and elsewhere4 ,to some extent this recurrent opposition was reasonable enough4 ,the new forms of locomotion had dangers of their own2 they were generally noisy and sometimes dirty2 and occasionally1 as in the case of early tramways1 they were a nuisance to existing traffic4 ,but it may be noted that electricity claims to provide a means of locomotion not only more rapid and more efficient 7in most cases7 than any other1 but free from many of the drawbacks which gave conservatism an excuse for opposing the introduction of steam and other forms of locomotion4 ,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 potentialities4 ,,chapter ,,ii ,,early ,,tramroads ,,and ,,railways ,it has sometimes been remarked1 by unfriendly critics1 that tramways are an apology for bad roads4 ,that is to say1 if road surfaces were perfect1 there would be no need to lay rails in order to allow vehicles to run easily4 ,although this view of the case may be no better than a quarter-truth1 it is justified to the extent that tramways were1 as a matter of fact1 the outcome of an attempt to escape from bad road surfaces4 ,in the early days of mining1 coals were taken by horsedrawn wagons from the pits to the harbours4 ,the passage and re-passage of heavy vehicles on the same roadway led to the formation of deep ruts2 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 transport4 ,the next step was to make the upper surface of the log round and the rims of the wheels hollow1 so that they fitted over the rails and kept the wagons on the track4 ,owing to the upper part of the rails wearing away quickly1 thin plates of iron were in some cases nailed to them4 ,this improvement led to the adoption of a cast-iron rail1 fastened to wooden sleepers4 ,the earliest cast-iron railway was laid down before the middle of the eighteenth century1 about one hundred years after the first wooden 'tram-ways4' ,half a century later we find the first rail-and-wheel combination as we know it on modern tramways and railways1 where the wheel carries an inner flange and runs upon the head of a narrow metal rail4 ,this is the form which experience has proved to be best adapted for safety1 speed1 and economy in power4 ,the improvements made since the beginning of the nineteenth century have been in matters of detail4 ,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 engineers4 ,they were concerned at first solely with the carriage of coal2 the idea of conveying passengers arose at a later date1 after the steam automobile had been tried and abandoned for the time being4 ,george ,stephenson1 for instance1 ran his first locomotives on colliery tramroads2 and the first railway--between ,stockton and ,darlington--was used for passengers merely as an afterthought4 ,it was1 in fact1 designed to be a tramroad for the use of the public in general transport by horse traction4 ,the most curious feature of this stage in the evolution of locomotion was that1 although ,stephenson's locomotives had been at work for several years and although several schemes of iron roads had been projected1 very few people had any conception of the development awaiting the locomotive and iron road in combination4 ,they did not even appreciate the proved fact that the locomotive was a more efficient means of transport than the horse4 ,an immense amount of pioneering work had to be done before the impression of a new era could be borne in upon the public mind4 ,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 7on the ,liverpool and ,manchester ,railway ,bill1 in #ahbe7 thought himself safe in suggesting that a steam locomotive could not start against a gale of wind4 ,when these prejudices were overcome1 many years had to pass before the objections of landowners and citizens were worn down4 ,railway engineers spent most of their time in a form of diplomatic warfare with opponents to their schemes2 huge sums--part of which still lingers in the capital accounts of railway companies--were spent in ,parliamentary proceedings over ,railway ,bills4 ,this barren process had to be repeated when electric traction made its appearance2 but happily the electrical fight was not upon quite so extensive a scale1 nor was the period of preparation followed by anything comparable to the ,railway ,mania of #ahde1 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 promoters4 ,the early history of the steam railway is interesting in connection with electrical locomotion for two reasons4 ,it shows that the railroad proper evolved out of the tramroad or 'light railway1' as it would now be called--a type of line which is specially suited to electrical operation4 ,it also includes a controversy between three modes of traction2 and this controversy forms a very good introduction to a discussion of the reasons why electricity is so economical in locomotion4 ,these three modes were 7#a7 stationary engines3 7#b7 locomotives3 7#c7 the device known as the 'atmospheric railway4' ,in both the first and third1 engine houses were placed close to the line at convenient intervals4 ,in the first1 each steam engine operated an endless rope to which the train of carriages was attached4 ,the system is still in use for colliery working and is also employed 7in an improved form1 of course7 for funicular railways4 ,george ,stephenson himself employed it to assist locomotives up heavy gradients4 ,in the atmospheric railway the stationary engines were used to exhaust the air from a length of cast-iron piping laid close to the railway4 ,the principle is the same as that of the 'pneumatic tube' which the ,post ,office uses for sending papers over short distances4 ,the papers are placed in a cylinder which fits the interior of the tube2 and when the air is exhausted from the tube in front of the cylinder1 the pressure of the air behind it drives the cylinder forward4 ,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 ,brunel4 ,but in point of fact it was recommended by two ,board of ,trade experts in #ahdb and by a ,select ,committee appointed in #ahde to consider several ,bills for atmospheric railways4 ,it was tried at ,dalkey and ,croydon1 and it was installed under ,brunel's supervision on a six-mile line in ,devon4 ,the carrier in the tube was connected to the train through a longitudinal slit at the top of the tube4 ,the slit was closed by a leather flap1 except when momentarily lifted by the passage of the train4 ,a great deal of ingenuity was exhausted in attempting to make this 'longitudinal valve' efficient1 but it was found that heat1 moisture1 and frost made the leather deteriorate so rapidly as to render it hopelessly ineffective in a short time4 ,after a series of misfortunes the atmospheric railway became a mere curiosity in the history of invention4 ,stephenson was right in regarding the atmospheric railway as 'only the fixed engine and ropes over again1 in another form4' ,he was also right in his belief that the steam locomotive was more economical than either of its rivals4 ,but the stationary engine idea had the germ of an even sounder principle than that of the locomotive4 ,both in electric tramways and electric railways the power is obtained from stationary engines4 ,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 trains4 ,there are other important differences2 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 annulled1 and it was found cheaper to put the engine on wheels and make it drag itself as well as the train4 ,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 traction4 ,he argued that stationary power1 if freed from incumbrances such as the friction and dead weight of a rope1 was superior to locomotive power1 on the following grounds3 7a7 ,a given amount of power may be supplied by a stationary engine at a less cost than if supplied by a locomotive4 7b7 ,the dead weight of a locomotive forms a large proportion of the whole travelling load1 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 trains4 ,experience has proved the soundness of these principles4 ,there has been a steady improvement in the power and efficiency of locomotives1 but progress has reached a point at which further increases in speed and accelerating power 7a very important matter7 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 speeds4 ,electric traction1 which is a reversion in part to the stationary engine system1 offers a means of escape from the limitations of the locomotive4 ,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 lines1 where distances are great and train loads heavy4 ,but the superiority is admitted on suburban lines and also on tramways1 where electricity has almost completely supplanted both horse and steam traction4 ,if ,brunel had foreseen how economical electricity would be in the transmission of power between engine and train1 he would have felt still more confident in his defence of the stationary engine4 ,,chapter ,,iii ,,the ,,birth ,,of ,,electric ,,traction ,the story of electric traction really begins in the laboratory of ,faraday4 ,he was the first to produce mechanical rotation by electrical means2 and1 although he had no practical end in view1 his investigations produced the germ of the commercial dynamo and thence of the commercial electric motor4 ,that germ1 however1 took about half a century to develop4 ,it is true that in #ahcg 7about ten years after ,faraday's discovery7 ,robert ,davidson experimented with an electric locomotive on the ,edinburgh and ,glasgow ,railway2 it is also true that ,jacobi1 two years later1 propelled a boat on the ,neva with electric power4 ,but these early attempts were not on a commercial scale4 ,not only was the motor a crude contrivance1 but the method of producing the electric power was hopelessly extravagant4 ,at that period the 'primary battery'--similar in character to those still used for laboratory purposes1 ringing electric bells1 and so on--was the best available source of electricity4 ,such batteries generate current by the chemical consumption of zinc4 ,in order to obtain sufficient power to move a boat1 a large number of batteries had to be coupled together4 ,they were expensive in first cost1 expensive in the zinc which was their 'fuel'2 and they became rapidly exhausted4 ,illustration3 ,,dynamo ,,motor ,fig4 #a4 ,diagram to illustrate the essential identity of the dynamo and the motor4 ,the dynamo generates electricity when the armature or group of coils is forcibly revolved close to magnets1 thus converting mechanical energy into electrical energy4 ,the motor causes its armature to revolve forcibly when current is supplied to it from the dynamo4 ,thus the motor converts electrical energy into mechanical energy4 ,the essential step towards the commercial plane was taken when an efficient means was devised for transforming mechanical into electrical energy on a large scale4 ,the first 'dynamo-electric' machines1 invented about the middle of last century1 were merely hand machines4 ,their power was limited by the strength of the permanent magnets employed in their construction2 and although an increase in power was obtained by multiplying the number of magnets and driving by steam power1 it was not sufficient for commercial purposes4 ,in #ahfg electro-magnets were first employed by ,siemens and ,wheatstone2 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 run4 ,it is unnecessary for our present purpose to enter into the technical details of the modern electric generator and the modern electric motor4 ,the principles underlying them are quite simple1 although the theory of their design and the practice of their construction and operation are almost a science in themselves4 ,a dynamo or electric generator is a machine for transforming mechanical into electrical energy2 an electric motor is a machine for transforming electrical energy into mechanical energy4 ,if1 therefore1 we place an electric motor upon a vehicle and supply it continuously with current from a dynamo1 the motor will rotate and can be used to propel the vehicle4 ,that is the essential mechanism of electric traction4 ,the simplicity of the arrangement is enhanced by the fact that the dynamo and the motor are virtually the same machine4 ,in the dynamo1 a cylindrical 'armature' of coils is forced to rotate close to the poles of electro-magnets2 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 armature4 ,in the motor1 which also consists of an armature close to the poles of electro-magnets1 the process is reversed4 ,when a current is passed through the coils of the armature1 the reaction between these currents and the electro-magnets causes the armature to revolve4 ,this reversibility of the dynamo was1 according to a story frequently repeated1 first discovered quite by accident4 ,in a ,paris exhibition a number of ,gramme dynamos--or dynamo-electric machines1 as they were then called--were being separately connected to lamps and other devices for showing the effect of electric currents2 and when one was started up it was found that another was being driven at a rapid rate4 ,investigation showed that the second one had been coupled up to the first by mistake and was therefore being worked as a motor by it4 ,this was in the year #ahgi2 and the story of the incident served to draw general attention to the discovery of a new and efficient means of transmitting power4 ,engineers recognised that in the steam-driven dynamo they had the means of producing powerful electric currents1 while in the electric motor1 connected by wires to the dynamo1 they had the means of reproducing the power in mechanical form at a distance4 ,there were1 of course1 losses of energy in the process4 ,a certain percentage was lost in the dynamo itself1 some in the transmitting wires1 and some in the motor4 ,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 distant4 ,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 dynamo4 ,this was done on the first electric railway by means of a 'third rail1' substantially in the same way as is now familiar on underground and other electric lines4 ,the third rail was a metal conductor supported on insulators and connected to the dynamo4 ,the vehicle or car was furnished with a metal brush or skate which rubbed along the third rail as the car moved forward4 ,the current thus collected was led through the motor 7which drove the axle of the car through toothed wheels7 and thence to the track rails1 which conveyed the current back to the dynamo and so completed the electrical circuit4 ,messrs ,siemens and ,halske exhibited the first electric railway of this type at the ,berlin ,industrial ,exhibition of #ahgi4 ,another method of collecting the current was tried soon afterwards and formed the direct forerunner of the electric tramway on the now standard 'overhead' system4 ,the disadvantage of the third rail system is that it involves an exposed 'live' conductor close to the ground4 ,it is therefore quite unsuited for use on streets4 ,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 track4 ,the first installation of this kind was laid down at the ,paris ,exhibition of #ahha4 ,in that case the conductor was an iron tube with a slot along its lower side2 and inside the tube was a 'boat' which slid along and was connected to the car by means of a flexible wire4 ,a second tube1 also with a boat and connecting wire1 was provided to carry the return current4 ,we shall see later how this arrangement evolved into the familiar 'trolley' system4 ,the mention of a slotted tube recalls the atmospheric system and1 in so doing1 emphasises the superiority of the electric system in simplicity1 flexibility1 reliability1 and economy4 ,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 system4 ,but there is an obvious contrast between the huge pipe of the atmospheric railway1 with its impossible 'longitudinal valve1' and the small tube of the first overhead electric line or the third rail of the first electric railway4 ,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 failure1 and the rapid ease with which electric traction entered into its kingdom when the commercial dynamo and motor were first produced4 ,the intrinsic difficulties which electric traction engineers had to meet were not serious4 ,designers passed1 step by step1 from the model electric railway at the ,berlin ,exhibition to public lines on a larger scale1 and from the model electric overhead tramway to the 'street railway' or tramway which gradually supplanted the horse tramway4 ,each step consisted in an extension of the distance covered and an increase in the power required1 coincident with a gradual improvement in the details of motors1 dynamos1 and transmission equipment4 ,,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 constitution4 ,it is distinctly curious to find an authority on locomotion describing the essential drawback of horse traction as its distinguishing advantage4 ,the 'vital principle1' unfortunately1 needs food and rest to maintain it not only during working hours but during the hours of inactivity as well4 ,in actual practice four horses out of every five in a tramway stud are in the stables while the fifth is at work4 ,moreover1 the same stud has to be kept up1 at a practically uniform cost1 whether the daily traffic be light or heavy4 ,thirdly1 the 'vital principle' has only a limited number of years during which--apart from sickness and disease--it is effective for traction purposes4 ,illustration3 ,fig4 #b4 ,a typical electric tramway on the overhead system4--,the trolley standard carries the wires for supplying current to the cars on both the up and down tracks4 ,the driver has his left hand on the controller handle and his right hand on the brake handle4 7,photograph reproduced by courtesy of ,dick1 ,kerr and ,company1 ,limited47 ,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 consumes4 ,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 necessary1 especially on an incline4 ,this was a recognition of the fact that the horse cannot cope easily with the heavy strain at starting1 and that he requires assistance on heavy gradients4 ,it was not surprising1 therefore1 that on horse tramway systems the speed was low1 the cars of limited capacity1 and the fares comparatively high4 ,the shortness of the journey which a tramway horse was able to cover without fatigue also tended to limit the length of routes4 ,on all these points electric traction was soon found to be distinctly superior to horse traction4 ,it was more economical in power2 it was able to maintain higher speeds with larger and more commodious cars2 and there was no narrow limit to the length of routes or the gradients which could be surmounted4 ,consequently electric traction offered the public an improved service at lower fares4 ,the whole of the power-producing plant for a typical electric tramway system is concentrated at a generating station placed 7if possible7 near the centre of the system4 ,from this station runs a network of electric mains to feed the lines with current at convenient points4 ,this concentration is a benefit on several grounds4 ,a large generating equipment is cheaper in first cost than a multitude of small power-producing plants1 and it is much more economical in operation4 ,if every car had its own power equipment1 that equipment would need to be powerful enough to haul itself and the loaded car up the steepest gradient on the route4 ,that is to say1 the sum of the car capacities would be equal to the sum of the maximum demands4 ,but when the power is obtained from a single stationary source we do away with the dead weight of the power equipment on the car1 and secure the very vital advantage that the capacity of the stationary source need not be so great as the sum of the maximum demands4 ,in actual working it never happens that all the cars are full of passengers and ascending the steepest gradients simultaneously4 ,while some are running up-hill1 others are going down-hill2 while some are full1 others are half full or almost empty4 ,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 car2 and the capacity of the generating station need be sufficient to cope only with the smaller amount4 ,this advantage reduces the expenditure necessary upon boilers1 engines1 and dynamos at the tramway generating station4 ,and it is enhanced by two valuable capabilities of the electric motor4 ,the first is its power of taking a heavy overload for a limited period without injury4 ,there is no difficulty about making an electric motor1 whose normal capacity is #bj horse power1 give #dj horse power momentarily1 #cj horse power for several minutes1 and #be horse power during the best part of an hour4 ,applied to tramway work1 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 system4 ,such maximum demands1 which only occur at intervals with each car1 can be met by the readiness of the electric motor for overwork4 ,the motors may therefore be reduced in size1 saving money in first cost and in the current consumed4 ,the second valuable peculiarity of the electric motor is that it gives its 'maximum torque' at starting4 ,that is to say1 it exercises the highest propulsive effort at the precise moment when it is required4 ,when horses are employed1 they have to endure an abnormal strain in overcoming the inertia of a stationary vehicle2 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 speed4 ,the electric motor--to use an apparent paradox--gives this abnormal pull as part of its normal action4 ,as the inertia of the car is gradually overcome1 the speed of rotation of the motor increases and its torque decreases1 automatically and precisely in accordance with the demands of the case4 ,the starting torque of a motor is such an emphatic phenomenon that the driver of an electric car may1 if he is careless and switches the current on too suddenly1 jerk any standing passenger off his feet1 even though the total weight of the car may be ten tons or more4 ,properly employed1 however1 the electric motor gives an even and rapid acceleration4 ,this is a far more important point in tramway economics than it appears to be at first sight4 ,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 passengers4 ,time is the vital element in all transport1 and it is especially vital in connection with tramways1 which have to stop with great frequency4 ,if the time which elapses between putting on the brakes at each stop and getting up to full speed again can be materially shortened1 then the average speed of the tramway journey can be materially raised4 ,it is easy1 by means of powerful brakes1 to bring a car to rest quickly2 the electric motor enables speed to be regained quickly4 ,in this way a high average speed may be maintained in spite of numerous stops2 and1 with larger cars1 the electric tramway is able to handle a larger volume of traffic in a shorter space of time than the horse tramway4 ,the time lost in stopping is of so much consequence that1 when electric tramways were introduced1 the old custom of stopping the cars at any desired point was abandoned4 ,stopping places were arranged at convenient points along the route1 some of them being regular stops and others optional at a signal from passengers desiring to alight or to board the car4 ,the public soon got used to walking a short distance to a stopping place1 although they did not1 perhaps1 appreciate how much the collection of traffic at a reduced number of points tended to improve the general tramway service4 ,a high average speed with numerous stops was1 however1 only one of the improvements which the public derived from electric traction4 ,tramway passengers expect to find a car not only at a convenient point but within a convenient period of waiting4 ,with electric traction the service became much more frequent than with horse traction4 ,it is quite possible to run a horse tramway service profitably with cars at intervals of fifteen to thirty minutes1 if the passengers are patient enough to wait and fill each vehicle4 ,but with electric traction the main item is the cost of the standing equipment--the power house1 mains1 and overhead lines--and unless that equipment is adequately utilised the revenue will not cover the standing charges4 ,a fifteen-minute service is1 generally speaking1 the lowest economic limit on an electric tramway4 ,every tramway manager tries to attract sufficient passengers for a more frequent service2 and1 as a matter of fact1 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 tramways4 ,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 another4 ,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 vehicle4 ,but with electric cars there is no extraneous limitation to carrying capacity4 ,large double-decked cars with seats for seventy passengers are now quite common4 ,in ,america it is a frequent practice to attach 'trailers' to the cars1 making a short tramway train4 ,experiments have recently been arranged on similar lines in ,london1 for the handling of the heavy traffic at rush hours4 ,these instances show that electric tramway capacity is flexible and may be adjusted to the density and the fluctuating character of the demand4 ,finally1 it falls to be noted that the power consumed by a tramcar is1 roughly1 proportional to the useful work which the car performs4 ,as already mentioned1 it costs about as much to work a horse tramway when the cars are empty as when they are full1 since the main item is the maintenance of the 'vital principle' of a certain number of horses independently of the traffic4 ,but with electric traction the motors require less power when the cars are running light4 ,and less current for the motors means less current generated at the power station--that is to say1 less steam1 less oil1 less coal1 less wear and tear4 ,if more current is demanded1 it is because more passengers are being carried and more revenue earned4 ,reviewing the subject broadly1 it is apparent that the adoption of electric traction on a tramway is not so much a step in advance as a beneficent revolution4 ,the higher speeds with more frequent1 more comfortable1 and more commodious cars have created a volume of traffic far beyond what could have been handled with horse traction4 ,the change also led to a great increase in the length of tramway routes and to the construction of new tramway systems4 ,in #ahih1 when the electric tramway movement began in earnest1 there were #ajfd miles of tramway in the ,united ,kingdom4 ,now there are #befb miles1 and the number of tramway passengers is more than double the total of third class passengers on the whole system of ,british railways4 ,the number of tramway passengers carried during #aiji-aj 7the last period covered by the published official returns7 was equal to about #fb times the estimated population of the ,united ,kingdom4 ,while the traffic has multiplied in this remarkable fashion1 there has been a heavy reduction in the fares charged4 ,this has been made possible by the economical features of electric traction4 ,in the old days a horse tramway had to spend about #hj to earn #ajj2 an electric tramway need spend only about #fj4 ,with this reduction in the proportion of expenses to receipts1 and with the greater volume of business1 it became feasible to stimulate traffic still further by giving passengers much longer distances for their money4 ,in fact1 electric traction proved so economical that people began to imagine that there was no limit to the reductions which might be made with financial safety4 ,however1 there is plenty of evidence that a limit exists4 ,in many cases it has been touched1 if not passed1 but the public continues to clamour for all sorts of concessions4 ,these demands are a great compliment to electric traction1 but they are a decided embarrassment to the tramway manager who believes in a reasonable margin between his total expenses and his total revenue4 ,,chapter ,v ,,the ,,mechanism ,,of ,,an ,,electric ,,tramcar3 ,,the ,,overhead ,,system ,a rough idea has already been given of the elementary mechanism of electric traction--the combination of generating station1 of cars fitted with electric motors1 and of a sliding contact between the two4 ,it is in connection with the sliding contact that the ingenuity of tramway engineers has been mainly exercised4 ,three distinct solutions were evolved for tramway work1 giving rise to three systems--7#a7 the overhead or trolley system2 7#b7 the conduit system2 and 7#c7 the surface-contact system4 ,the first system is now almost universal in the ,united ,kingdom4 ,part of the ,london system is equipped on the conduit system2 and the tramways at ,lincoln and ,wolverhampton are constructed on the surface-contact system4 ,beyond these cases the trolley holds the field4 ,in the ,united ,states and on the ,continent there is a larger proportion of conduit work1 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 rise4 ,illustration3 ,fig4 #c4 ,diagrammatic illustration of the general arrangement of an electric tramway on the overhead system4 ,at the foot is shown the generating station which supplies alternating current at high-pressure 7for economy in transmission7 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 current4 ,the course of the current through the trolley pole and controller and thence to the motors and back by the rails is indicated by arrows4 ,the overhead system has conquered because it is cheapest in first cost1 cheapest to maintain1 most economical in current1 and most reliable in action4 ,later developments in surface-contact traction have run it very close on some of these points1 but have not--for reasons which will be explained--affected the established position of the overhead system4 ,in its essential features the overhead system has not altered very much from the experimental line erected at the ,paris ,exhibition of #ahha4 ,the slotted tube has been replaced by a solid copper wire2 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 springs4 ,the sliding bow is common on the ,continent1 but it has been adopted on only one ,british tramway--that at ,sheerness4 ,its use for electric traction on railways will be mentioned later1 but as far as ,british tramways are concerned the bow is the exception which proves the trolley wheel rule4 ,the function of the trolley wheel is to collect current from the wire along which it rolls4 ,this current passes through insulated wires down the trolley arm to the controller1 which the driver of the car operates by means of a handle4 ,the controller1 which is really a series of electrical resistances1 is analogous to a water tap4 ,by its means the current may be completely shut off from the motors1 or allowed to flow in varying degree as required by the speed of the car4 ,in starting a car1 the driver moves the controller handle notch by notch1 so as to get a uniform rise in speed until the full current is allowed to pass through the motors4 ,with such a mechanism1 supplemented by brakes1 the driver has the movements of the car under control4 ,in a four-wheeled car1 each axle is driven by a motor4 ,in a bogie car 7one with a set of four wheels at each end7 the axles of the larger wheels of the bogie are each driven by a motor2 but not directly4 ,considerations of space make it necessary to keep the motor as small as possible1 but if a motor is to be small and also powerful it must rotate at a high speed4 ,on the tramcar1 therefore1 the motor drives a small toothed wheel which drives a large toothed wheel fixed to the axle1 thus effecting a reduction of speed between the motor and the wheel4 ,the same considerations of space join with others in making two motors on each car the general rule4 ,and the use of two motors enabled the tramway engineer to introduce a refinement into the method of control4 ,this refinement is known as the 'series-parallel system4' ,one of its objects is to give a large 'starting torque' and so enable the car to gain speed quickly4 ,when the current is first switched on by the controller it passes through the motors in tandem or in 'series1' thus dividing the pressure of the current 7analogous to a 'head' of water7 between them4 ,the starting torque of a tramway motor 7or the turning moment which it exerts when current is first passed through it7 is dependent on the current but independent of the pressure4 ,thus the tandem or 'series' arrangement1 which passes the full current through each motor1 gives the maximum starting torque without an undue consumption of current4 ,after the car is well started1 the next movement of the controller puts the motors in 'parallel1' opening up two paths for the current instead of one1 so that each motor receives the full pressure4 ,the practical result is that there is a very rapid acceleration at starting1 with marked economy in current4 ,if the motors were kept in 'parallel' right through1 twice as much current would be required to get the same starting torque4 ,it will be seen later how valuable this arrangement for getting a rapid start1 without excessive current consumption1 may be in improving the physical and economic conditions of a tramway or train service4 ,after having passed through the motors and done its work1 the current is led to the wheels of the car and returns by way of the rails1 which are linked together by copper bonds so as to form a continuous conductor4 ,the passage of the current from the wheel to the rail is indicated by sparks when the rails are rough or very dry and dirty4 ,although the rails1 like the overhead wires1 are thus carrying current1 there is no danger of shock from them1 as the electrical pressure in them is only a few volts1 at the outside1 while the pressure in the overhead wires is #ejj volts4 ,it is this difference of pressure which--like the 'head' of water in a turbine--supplies the motive power for the car4 ,each car on a tramway system may thus be regarded as a bridge which completes an electrical circuit4 ,when the driver moves his controller1 current flows from the generating station at a high pressure1 passes through the controller1 operates the motors1 and returns to the generating station at a low pressure4 ,this typical circuit is completed through every car1 so that the demand on the generating station at any moment is the sum of the demands of the cars at that moment4 ,the business of the engineer at the generating station is to maintain the electrical pressure in the overhead wire at the normal level of #ejj volts2 and in order to do this on an ordinary tramway system it is found convenient to divide the overhead wire into half-mile sections1 each of which has a separate main or 'feeder' from the generating station4 ,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 another4 ,at the same spot he can see the short square 'feeder-pillar' at the roadside 7containing the switches by which current can be turned off from that section7 and the cables which pass along the arm of the trolley standard and terminate in the overhead wire4 ,on an extensive tramway system the power-supply arrangements become more complicated4 ,the central generating station remains the primary source of power1 but sub-stations are erected at convenient points between the central station and the outskirts of the tramway area4 ,these sub-stations are secondary stations for the distribution of electricity4 ,they receive power at extra-high pressure 7#ejjj volts or more7 from the central station2 they contain special machinery for reducing the pressure to #ejj volts for distribution to the various tramway feeders4 ,the object of this arrangement is partly technical but mainly economical4 ,electric power can be transmitted at a lower cost in mains and with less loss of energy at high pressures than at low4 ,consequently when the termini of tramway routes are several miles from the generating centre1 greater all-round efficiency is secured by transmitting current at high pressure to a number of well selected sub-stations4 ,illustration3 ,fig4 #d4 ,photograph of a car on a conduit section of the ,london ,county ,council tramways4 ,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 conduit4 7,photograph reproduced by courtesy of ,dick1 ,kerr and ,company1 ,ltd47 ,,chapter ,,vi ,,conduit ,,and ,,surface-,,contact ,,tramway ,,systems ,roughly speaking1 the arrangements for generating electricity1 distributing it1 and utilising it on the car1 remain the same in conduit tramways and surface-contact tramways as on the overhead system4 ,the differences between the three systems are1 as already indicated1 confined to the means of collecting the current for each car4 ,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 street4 ,the cable tramway1 with its concrete trough and slot1 gave an obvious hint4 ,there would be no difficulty1 apparently1 in carrying wires on insulators in the trough or conduit1 and utilising the slot for a 'plough' which would slide along inside the conduit1 keeping contact with the wires1 and so conveying the current to the car4 ,this was tried for the first time in ,blackpool1 where--in #ahhd--;a length of conduit tramway was laid along the front street of the town4 ,the conditions could hardly have been less favourable for the system1 as the sea frequently washed over the roadway1 flooding the conduit with water and sand4 ,further1 the conduit was so shallow that children were able to get at the conductors with their metal spades4 ,as the conduit carried the return wire1 the effect of a metallic contact between the two conductors was to cause a 'short circuit1' with very entertaining fireworks but with no amusing results for the tramway engineer4 ,after a heroic trial1 the system had to be abandoned4 ,bournemouth was the next ,british town to adopt the conduit4 ,it did so as a token of its exceptional civic pride4 ,three times1 in fact1 the ,bournemouth ,corporation declared that it did not want tramways of any kind whatever within its gates4 ,and when the pressure of public opinion forced its consent1 the arrangement was made that no overhead wires should appear in the central district of the town4 ,several miles of conduit tramway were therefore constructed 7the trolley system being used for the outer tramway routes72 and as by that time a good deal of experience had been gained in conduit work both in ,america and on the ,continent1 the contractors were able to give the ,corporation a conduit system built to endure4 ,at first the ,corporation was reconciled to the fact that the conduit sections had cost about twice as much per mile as the trolley lines1 but as years went on1 and as the financial results of the system continued to prove unsatisfactory1 the ,corporation's contentment became modified4 ,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 order4 ,since the public had got used to the overhead wires on the other sections1 and since they had not got used to owning tramways which produced a heavy loss1 the decision was made to abandon the conduit system altogether4 ,in ,london the conduit system was adopted by the ,london ,county ,council for various reasons4 ,one was that the ,council felt that ,london ought to have the best1 the very best1 and nothing but the best4 ,another was that the streets were so congested with traffic1 lamp standards1 telegraph and telephone poles1 and other obstructions1 that trolley wires and trolley standards would be a great nuisance and a serious danger4 ,aesthetic reasons were also advanced1 but it is difficult to realise that they had much weight in connection with the majority of metropolitan streets4 ,trolley wires were1 in fact1 freely erected in suburban streets where there was a certain amount of beauty worth preserving4 ,the main underlying reason1 no doubt1 was the feeling that ,london could afford the most costly system4 ,in any ordinary city 7and perhaps in ,london as well7 the conduit must be regarded as a luxury4 ,it involves a continuous road excavation so deep that a great deal of incidental work has frequently to be done in moving gas1 water1 and drain pipes out of the way4 ,the conduit itself is a thick channel of concrete1 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 passes4 ,elaborate arrangements have to be made for draining the conduit1 as any accumulation of mud or water in contact with the conductors1 or the special insulators supporting them1 would be fatal to the working of the system4 ,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 running4 ,heavy rains and snowstorms are therefore liable to upset the working of the system2 and the tramway manager has to employ quite an army of men simply to keep the conduit in working order4 ,trouble is also apt to be caused by purely mechanical means4 ,on one occasion a child's hoop fell through the slot and caused a short circuit4 ,as the ordinary scrapers slipped over the hoop1 its presence was not detected for a considerable time1 during which the tramway service was at a standstill4 ,altogether there is a greater liability to interruption on the conduit system than on the overhead system4 ,illustration3 ,fig4 #e4 ,the upper portion of the illustration shows a section of a typical conduit system of electric tramway traction4 ,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 rails4 ,the lower illustration gives a longitudinal and transverse section of the ',g-,b4' system of surface-contact tramway traction4 ,the rope-like cable carries the current and is supported on insulators4 ,when the collector on the car covers the stud1 the action of the magnet draws the lower part of the stud into contact with the cable1 thus supplying current to the car4 ,after the car has passed1 the lower part of the stud rises by the action of a spring and1 breaking contact with the 'live' cable1 becomes dead4 7,in actual practice contact would be made under the conditions shown in the left-hand diagram47 ,experience of these drawbacks led the ,london ,county ,council to seek an alternative to the conduit when constructing electric lines in the north of ,london4 ,many of the borough councils1 following the ,county ,council's own previous arguments1 would not listen to the suggestion of the overhead system2 and a freshly-elected ,council1 pledged to a policy of economy1 determined to try the surface-contact system4 ,how this trial gave rise to a violent political controversy1 leading to the abandonment of the project and culminating in important libel actions1 forms a picturesque story which need not be told in detail here4 ,its main interest lies1 for the moment1 in the emphasis which the incidents give to a characteristic of the surface-contact system--its sensitiveness to minute alterations in detail4 ,the surface-contact or 'stud' system is really a modification of the conduit system4 ,it has1 in fact1 been called the 'closed conduit4' ,the electric wires are again placed in a channel or pipe underground1 but instead of being accessible through a slot1 contact can be made with them only through metal studs placed at intervals flush with the roadway4 ,by special electro-mechanical devices in the stud and on the car1 the stud is brought into contact with the 'live' underground wire only when the car is over it4 ,that is to say1 the studs covered and protected by the car will be 'live' and supplying power to the car through a sliding brush or 'skate1' while those not so protected will be 'dead' and therefore of no danger to the public4 ,an immense amount of ingenuity has been expended by many engineers in devising studs to act with absolute certainty under all conditions4 ,in the laboratory or the workshop1 and even on an experimental track1 it was simple enough to arrange a mechanism which would 'make' and 'break' contact with admirable regularity4 ,but when it came to putting the mechanism down on an ordinary roadway1 to be covered with mud1 pounded by heavy traffic1 and subjected to the action of damp1 frost1 heat1 and all sorts of unexpected influences1 much less satisfactory results were obtained4 ,time and again the hopes of engineers were dashed by a succession of petty troubles--some of them obscure1 most of them unforeseen4 ,the weak points in nearly all the systems were the insulation of electrical parts and the road construction work4 ,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 them4 ,but even after the practical elimination of these troubles the success of the surface-contact system seemed as sensitive as the system itself4 ,one system was tried at ,torquay1 and discontinued after a protracted trial on a large scale4 ,another system--the ,lorain system--was installed at ,wolverhampton and is still in operation1 but without imitators4 ,a third system--the ,griffiths-,bedell or ,g-,b4 system--was installed in #aije at ,lincoln1 with satisfactory results4 ,it was the ,g-,b4 system which was offered to the metropolitan borough councils as an alternative to the conduit and the trolley4 ,a trial section was laid down in #ahih in the ,bow ,road1 and a certain amount of trouble was experienced with live studs and with various parts of the equipment4 ,owing to the stud system having been suggested by the ,moderate ,party1 the experimental difficulties were extensively advertised by members of the ,progressive ,party1 who condemned the system as dangerous and unworkable4 ,public feeling was worked up to such a pitch that1 in the face of expert advice in favour of the system in a somewhat modified form1 the ,council decided to abandon the experiment4 ,libel actions by the owners of the ',g-,b4' patents followed1 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-,b4' system proper4 ,the results with the ',g-,b4' system at ,lincoln prove that it is possible to construct surface-contact tramways at a cost about #aj per cent4 more than that of trolley tramways1 and to operate them1 safely and with reliability1 at a cost not appreciably more than the general working expenses of an overhead line4 ,but this proof has not only been enfeebled for the special reasons just described1 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 traction4 ,ten or fifteen years earlier1 such a proof might have changed the course of tramway development2 now it can have no great material effect4 ,the upshot of the contest between the three systems has1 therefore1 been the survival of the one which was most despised at the outset4 ,,chapter ,,vii ,,the ,,backwardness ,,of ,,electric ,,traction ,,in ,,great ,,britain ,popular objections to the overhead system are not1 of course1 quite dead4 ,every tramway proposal in districts where the trolley has not already penetrated is still opposed on the ground of disfigurement and danger4 ,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 cities4 ,but the dislike of the public for a questionable novelty was not the sole reason why electric tramway enterprise was backward in ,great ,britain4 ,it is not strictly accurate to say that electric tramway enterprise was backward4 ,the enterprise was there1 in spirit1 but circumstances were very much against it4 ,tramway schemes are controlled by special legislation which was passed before electric traction was contemplated2 and this legislation has not been amended in any material degree to suit the altered conditions brought about by the use of electricity4 ,the ,tramways ,act1 #ahgj--which is the master ,act of the situation--was framed at a time of reaction against public monopolies4 ,before that time1 gas1 water1 railway1 and other companies had been granted statutory powers in perpetuity2 and when a local authority wanted to take the supply of gas or water into its own hands1 it had to buy the existing undertakings at the valuation put upon them by the owners themselves4 ,there were frequent complaints about excessive purchase terms1 and also about extortionate rates charged by the monopolist companies4 ,consequently1 when horse tramways came on the scene1 the legislature determined to put the new 'monopoly' on quite a different basis4 ,the ,tramways ,act provided1 first1 that no application for tramway powers would be so much as considered if it did not gain the consent of the local authorities interested2 second1 that the period of tenure should be limited to twenty-one years2 and third1 that the local authorities should have the option1 at the end of the period or at seven-year intervals afterwards1 of buying the tramway undertaking at the 'then value' of the plant 7rails1 horses1 cars1 depots1 etc47 without any allowance for compulsory purchase1 goodwill1 future profits or any other consideration whatsoever4 ,this ,act was passed with the very best of intentions4 ,it had the advantage of substituting1 for the costly and clumsy procedure by ,private ,bill1 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 7in a more or less automatic way7 by ,parliament4 ,but in spite of its good intentions it proved a serious stumbling-block1 especially when electric traction was proposed4 ,the effect of the limited tenure system1 with compulsory expropriation on what were called 'scrap-iron' terms1 was to make the companies very reluctant to spend one penny more than was absolutely necessary during the concluding years4 ,capital expenditure on improvements in equipment was regarded as out of the question1 since there was not sufficient time to recoup the difference between first cost and the 'then value' at the purchase period4 ,money was grudged for the upkeep of track1 the repair and painting of cars1 and the hundred and one items of expense which are essential to a well-conducted tramway4 ,system after system fell into a state of shabby gentility1 hoarding money against its inevitable end4 ,this was the condition when1 in the middle eighties1 electric traction was suggested4 ,the public1 suffering from the decay of the tramway service1 but not realising that the cause lay with an ,act devised for the public benefit1 expected the tramway companies to adopt the new mode of propulsion4 ,but as the conversion to electric working involved track-work costing several thousands of pounds per mile1 and new cars costing several hundreds each1 together with a large generating plant and new car depots1 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 expropriation4 ,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 undertake4 ,thus a strong impetus was given to municipal tramway enterprise4 ,but this impetus did not remove the causes of delay4 ,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 terms4 ,they were also obliged to move very cautiously in adopting so radical and so novel a change as electric traction4 ,municipalities are not speculative traders1 who are ready to take risks after a rapid expert investigation of a new policy4 ,further1 no municipality likes to accept the decision of another as valid for its own district4 ,the consequence was that each municipality thought it necessary to get its own expert report on the subject and1 in many cases1 to send its own deputation to inspect ,continental tramway systems4 ,these preliminary studies1 with debates in ,council chambers and newspaper columns1 with public meetings of encouragement or protest1 and with the erection of experimental lines1 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 working4 ,the municipalities1 however1 were not the only forces at work4 ,towards the year #ahif1 when a large number of tramway leases were running out1 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 routes4 ,the essential condition of the success of such enterprise was1 of course1 the renewal of the tenure of the tramways for at least another twenty-one years4 ,here--and in the accompanying applications for extensions of route--the true inwardness of the ,tramways ,act was shown4 ,everything was in the hands of the local authorities4 ,they had only to withhold their consent1 and nothing could be done4 ,and this power of veto enabled them to drive any bargain they pleased with the promoters of tramway schemes4 ,most electric tramway proposals covered the areas of several local authorities1 so that negotiations had to be entered into with each in turn4 ,the municipalities1 being the guardians of the public interests1 considered it their duty to impose the heaviest conditions which the promoters could be induced to accept1 rather than abandon the enterprise4 ,it was a case of ,hobson's choice in every parish4 ,in some instances direct payments for wayleaves were demanded4 ,in others the promoters were forced to bear the cost of street widenings and other 'public improvements' which were not always necessary for tramway purposes4 ,in nearly every town the fares and stages were determined by the local authority--on the strength of the veto1 not on commercial principles4 ,the cost of construction was frequently increased by onerous conditions regarding the standard of overhead wire and track work4 ,under the ,tramways ,act1 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 used4 ,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 surface2 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 traffic4 ,one effect of this state of affairs was delay4 ,the preliminary negotiations with local authorities--the interviews with mayors1 aldermen1 councillors1 town clerks1 and borough surveyors1 to say nothing of the 'frontagers' along the line of route--usually occupied far more time than the actual construction of the tramways4 ,they were also much more troublesome1 since it was within the power of a single local authority in a central position to 'hold up' a complete scheme1 while most districts had strong local patriotism and wanted a municipal system to themselves4 ,very little is known by the general public of the anxiety1 difficulty1 and expense attending such negotiations with local bodies divided into parties or cliques and furnished with an absolute power of veto4 ,looking back on the history of electric traction1 it really seems extraordinary that engineers and financiers had the patience to undertake this work and carry it through4 ,their reward1 as will be seen1 was not great in a pecuniary sense2 and1 as regards reputation1 they are generally accused of being extravagant1 avaricious1 and wanting in enterprise4 ,the ultimate effect was that the actual cost of electric tramways exceeded the estimates prepared on the basis of ,continental and ,american experience4 ,the more prolonged and difficult the negotiations preliminary to a scheme became1 the greater the expense4 ,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 tramway4 ,the ,board of ,trade assisted the increase in cost by prescribing a standard of construction which was higher than that allowed in other countries4 ,the net result has been that while electric tramways were expected to cost about #iejj per mile1 they have actually cost over #ab1jjj per mile4 ,the revenue side of the account has also been affected by the power of veto4 ,a local authority has no hesitation in imposing low fares and long stages 7with high wages and short hours for employees7 upon a tramway company seeking its consent4 ,the standard usually adopted is that of large urban systems with dense traffic1 so that systems in scattered districts are often unfairly treated4 ,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 facilities4 ,workmen's fares1 for instance1 are a dead loss on practically every tramway system4 ,every now and again there is an agitation for halfpenny fares1 for the extension of stages1 for cheap rates for school children1 for free transport for the blind1 and so on4 ,a leading municipal tramway manager once remarked that it was almost impossible for men in his position to resist the pressure for such concessions1 especially at local election periods4 ,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 fares4 ,most of the large urban systems are under municipal control1 and therefore they have the rates in reserve1 as well as the most favourable traffic conditions1 to encourage them in giving the public more and more for less money4 ,but the tramway companies1 working for the greater part in less thickly populated areas1 with no extraneous means of making up losses1 are put in a difficult position when similar concessions are forced upon them4 ,the upshot is that the average return on the capital of electric traction companies amounts to only #cda per cent4 ,better profits were1 in fact1 made in the horse tramway days2 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 public1 which shows its gratitude by asking for greater blessings at their expense4 ,,chapter ,,viii ,,electric ,,tramway ,,stagnation4 ,,the ,,trolley ,,omnibus ,the revenue of a tramway is built up of pennies2 and a minute increase in the average earnings per passenger will therefore have a large effect on the total receipts4 ,for instance1 it was calculated 7in #aijg7 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 #bjj1jjj in the revenue4 ,similarly1 a fractional decrease in one of the operating expenses--say1 the cost of electric current--might transform a shaky undertaking into a sound one4 ,tramway finance1 in fact1 is a question of infinitesimals4 ,so long as fares are determined by arbitrary conditions1 little can be done to increase the revenue on an electric tramway system4 ,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 it4 ,apart from the development of parcels traffic1 his best opportunities lie in the skilful adjustment of the service to the varying needs of the public1 so that the 'rush' hours find an adequate supply of cars1 while the quieter hours find no 'waste car mileage' in the form of empty cars4 ,he can also do a good deal in the way of inducing the drivers not to waste current4 ,by putting an electricity meter on each car it is possible to check the current consumption and1 by a system of bonuses1 to encourage the economical driver4 ,there are many other directions in which small financial leakages may be arrested1 giving an aggregate saving which is well worth the trouble4 ,illustration3 ,fig4 #f4 ,photograph of an electric trolley omnibus built by the ,railless ,electric ,traction ,company ,ltd4 in #aiji and operated at ,hendon for experimental purposes4 ,later cars built by this company are of a lighter and simpler design1 but the illustration shows clearly the arrangement of a double trolley for supplying current to a vehicle which 'steers' like an ordinary motor omnibus4 ,the fact remains1 however1 that on the whole the electric tramway business depends upon too narrow a margin between costs and receipts4 ,the recognition of this fact1 coupled with the legislative difficulties already described1 led to the practical cessation of tramway development in ,great ,britain at a point far short of what was once expected4 ,at one stage1 no doubt1 people were a little too enthusiastic about electric traction4 ,they imagined that electric traction would create profitable traffic along the most deserted of side streets4 ,acting on that theory1 municipalities constructed--or forced tramway companies to construct--lines along roads which could never supply enough traffic to justify the expenditure involved4 ,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 earned4 ,however1 after every allowance is made for such local excesses of enthusiasm1 the under-developed condition of electric traction in ,great ,britain remains conspicuous enough4 ,a sensible relaxation of legislative restrictions would go a long way to improve matters--if1 that is to say1 financiers could be induced to re-enter a field in which they have had many disappointments4 ,great hopes of improvement were entertained when the ,light ,railways ,act1 #ahif1 was passed4 ,the primary object of this ,act was to encourage the building of cheap railways for agricultural and fishery purposes1 but it was drafted on lines broad enough to include electric tramways4 ,arrangements were made for ,state and local contributions to the cost of such schemes1 in cases where subsidies appeared to be justifiable4 ,the procedure in obtaining powers was made as simple and as economical as possible4 ,applications for ',light ,railway ,orders' had to be made to the ,light ,railway ,commission1 one of whose members then arranged to hold a local inquiry into the proposal4 ,if sanctioned1 the scheme was passed on to the ,board of ,trade for approval1 and the ,order1 if confirmed1 thus secured the validity of a ,private ,act of ,parliament4 ,nothing was said in this ,act about the consent of local authorities1 or about limited tenure1 or about expropriation upon scrap-iron terms4 ,but the ,light ,railway ,commissioners chose to interpret the ,act in terms of the ,tramways ,act1 with the result that1 when there was any opposition on the part of local authorities1 the tramway promoter using the ,light ,railways ,act was not much better off than before4 ,he had to face a new difficulty in a clause of the ,light ,railways ,act1 which provided that when the proposed light railway was of sufficient magnitude and in such a position that it offered competition with an existing railway1 the scheme should be submitted to ,parliament as a ,private ,bill--that is to say1 should face the most costly and cumbersome procedure of all4 ,the ,light ,railways ,act thus proved a great disappointment4 ,its failure to afford relief seems to have taken away the tramway promoter's last hope of genuine legislative betterment4 ,he has resigned himself to things as they are2 and the utmost he does is to assert1 when occasion offers1 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 alone2 if arrangements were made for obtaining wayleaves and land on favourable terms1 and if he were allowed to construct and equip the line on a less costly basis than the ,board of ,trade now demands1 even in rural districts4 ,pending that revolution1 tramway authorities are seeking to develop a cheaper means of electric traction than the tramway4 ,at the present stage1 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 extension4 ,inter-urban tramway systems--those connecting towns with a network of lines--are also adjacent to such minor centres of traffic4 ,from time to time attempts have been made to meet the demand by means of petrol omnibuses1 but they have rarely been successful--partly1 no doubt1 owing to the difficulty of working a limited petrol omnibus service economically at the extremities of an electric tramway system4 ,the latest solution of the problem is the 'trackless trolley' or1 more correctly1 the 'trolley omnibus4' ,in the #aiaa session over a dozen tramway authorities applied for powers to use this device2 and1 if the financial results of the first attempts are successful1 there will probably be a considerable growth in this type of electric traction4 ,the trolley omnibus is a hybrid between the trolley tramcar and the omnibus4 ,it is akin to the first1 because it derives its power from an overhead wire through a flexible trolley pole4 ,it is akin to the second1 because it does not run on rails but is fitted with solid rubber tyres and uses the surface of the road in the usual way4 ,roughly speaking1 its electrical equipment is similar to that of a tramcar4 ,the trolley pole conveys the electric current to the controller1 which admits it to motors geared on to the back axles4 ,there are1 however1 one or two important differences4 ,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 it4 ,thus the electrical circuit is from the power station1 along the first overhead wire1 down the first trolley-pole1 through the controller and motors1 up the second trolley-pole1 and back by the second overhead wire to the power station4 ,owing to the vehicle being a steerable one1 the trolley-poles have to be specially designed to give plenty of free play sideways4 ,the vehicle itself is similar in appearance to a single-decked motor omnibus1 and it runs on solid rubber tyres or spring wheels4 ,the first thing which strikes one about the trolley omnibus in comparison with the electric tramcar is the cheapness in first cost4 ,all the expense of concrete foundations1 heavy rails1 and granite paving is avoided4 ,on ordinary roads the overhead construction is much less costly1 as a single line of poles supporting two wires is sufficient for the up and down services4 ,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 system4 ,following on this economy there is the saving in the cost of maintenance and repairs--a serious item on the ordinary tramway4 ,in actual working1 the system has the advantage that the vehicles can steer past slow-going traffic1 thus avoiding the delay caused on tramway systems through carts having to draw out1 away from the track1 when overtaken by cars4 ,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 track4 ,when there is only one pair of wires1 two trolley omnibuses may pass each other 7whether going in the same or opposite directions7 by the simple process of pulling down the trolley poles of one car and swinging them out of the way for a few seconds4 ,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 simultaneously4 ,the other side of the picture is shown when we come to look into the costs of working4 ,no matter how good the road surface may be or how excellent the design of the wheel1 the tractive effort required for a trolley omnibus must be relatively greater than that required for a tramcar4 ,nothing demands a lower tractive effort than a steel wheel running on a steel rail4 ,consequently the trolley omnibus takes more power per ton moved than the tramcar4 ,when the road surface is wet or uneven1 or muddy or loose1 this difference is of course multiplied4 ,another addition to the working cost is produced by the tyres1 which1 if of rubber1 may wear away at the rate of #a-a_/b;d4 or #b;d4 per mile per vehicle4 ,owing to the uniform control of speed afforded by the electric system1 there is less jerking at starting or stopping than is general with a petrol-driven omnibus2 but in spite of that advantage1 tyre wear on a trolley omnibus must remain an important item4 ,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 rails4 ,the balance between these advantages and disadvantages is not easy to strike1 even on a general basis4 ,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 facilities4 ,all they had to go upon was the experience gained on certain ,continental routes1 where trolley omnibuses have been running for several years4 ,that experience encouraged the hope that trolley omnibuses might be a profitable means of developing traffic in conjunction with a tramway system1 and along routes which would not provide sufficient business for a regular tramway4 ,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 system4 ,as a general proposition1 nothing could be further from the truth4 ,tramway authorities have adopted the new system in certain cases where the possible traffic is comparatively small1 not as a substitute for tramways1 but as an alternative to self-propelled omnibuses4 ,the carrying capacity of a trolley omnibus is about twenty1 while that of a tramcar is frequently as high as seventy4 ,the speed of a tramcar runs up to twenty miles an hour1 while twelve miles an hour is as much as is comfortable 7to say the least7 with a vehicle running with solid tyres on an ordinary road4 ,therefore1 where large volumes of traffic have to be handled swiftly1 the tramway will remain4 ,but where a twenty-minute or half-hourly service of small vehicles is sufficient for the available passengers1 a system which is much cheaper in first cost is clearly more suitable1 even though it may not reach the standard of economy in working set by the large urban tramway4 ,that is to say1 the choice between the two systems depends entirely upon local circumstances4 ,illustration3 ,fig4 #g4 ,the 'auto-trolley' system of electric traction applied to the haulage of goods in a ,german quarry4 7,from ,electrical ,industries47 ,as an emphasis upon this statement1 it is significant that many tramway engineers regard the trolley omnibus merely as the forerunner of a tramway4 ,for this reason they favour the adoption of the particular trolley omnibus system where the overhead equipment is adaptable with trifling changes to tramway purposes4 ,they argue that1 in the case of a village of a few thousand inhabitants1 situated a mile or so beyond the terminus of a tramway route1 a trolley omnibus service will not only be sufficient for the existing traffic1 but will show whether the traffic is likely to increase 7through the stimulation of building enterprise7 up to the point where it would make the laying of rails worth while4 ,when that point is reached1 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 'feeler4' ,,chapter ,,ix ,,regenerative ,,control ,before going on to discuss the 'accumulator' or 'storage battery' system of electric traction1 reference should be made to an invention which holds the germ of great economies in electric traction4 ,this invention is known under the name of 'regenerative control4' ,it has already been explained that the dynamo is reversible--that is to say1 a dynamo may act as a motor1 or a motor as a dynamo4 ,this fact is usefully applied in braking tramcars4 ,when a car has gained speed1 its momentum represents a certain amount of stored energy4 ,in stopping the car1 this energy has to be absorbed or dissipated in some way or other4 ,one method is to utilise the friction of brake blocks on the wheels1 or of skids on the rails themselves4 ,with the electric car1 however1 it is possible to absorb the energy by making it drive the motors as if they were dynamos4 ,the moving car drives the wheels1 which in turn drive the motors2 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 rails4 ,in any of these cases a car which is being stopped1 or is being 'held back' by the brakes when going down-hill1 is wasting power4 ,it is clear1 therefore1 that a great deal of power could be saved if the current generated by the motors in retarding could be pumped back1 as it were1 into the electrical circuit4 ,this is the problem of 'regeneration' which has fascinated many electrical engineers4 ,the practical difficulties underlying it are very great2 and perhaps the only man to get within measurable distance of surmounting them was ,mr ,j4 ,s4 ,raworth1 whose system of regenerative control was tried on a number of tramway systems and installed on the ,rawstenstall tramways in #aiji4 ,it cannot be said with confidence that all the difficulties have been overcome2 on the other hand1 it would be rash to say that they are insurmountable4 ,mr ,raworth1 at any rate1 retains his faith in ultimate victory2 and the theoretical beauty of the system is so complete that it is bound to retain its fascination4 ,the practical result of regeneration is to eliminate the effect of hills4 ,a regenerative car in descending a hill gives back to the generating station some of the excess energy required to take it up the hill4 ,in the same way each car1 in coming to a standstill1 gives back a portion of the energy required to start it4 ,a regenerative tramway may thus be represented1 from the energy point of view1 as one in which all the cars are running at normal speeds on level roads4 ,incidentally the regenerative system gives a very perfect control of the speed of the car on all gradients1 owing to the regeneration which begins automatically when the motors start 'coasting4' ,it is a power-saver and a brake in one2 and its efficacy as a means of control is so great that1 if its incidental drawbacks could be avoided1 it would be worth adopting for this purpose alone1 both on electric tramways and on electric railways4 ,,chapter ,x ,,accumulator ,,electric ,,traction4 ,,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 another4 ,its history serves to remind us that the problem of cheap transport is really a group of problems1 each one of which demands a particular solution4 ,the accumulator is a device for storing electrical energy in the form of chemical energy4 ,its action depends upon the effect of currents of electricity on lead plates in a bath of sulphuric acid4 ,the passage of the current through the battery produces chemical changes which enable the battery to give out current when required4 ,as the battery may remain 'charged' for several days1 and may be discharged slowly or quickly1 it provides a means of 'storing' electrical energy4 ,in practice1 and under favourable conditions1 the efficiency of the storage battery is about #hj per cent4 ,that is to say1 there is a loss of about #bj per cent4 in the process of conversion and re-conversion4 ,illustration3 ,fig4 #h4 ,a modern electric automobile4--,the electric battery is placed under the front half of the car1 and the motors drive the back axle through chains4 7,british ,electric ,automobile ,co41 ,ltd47 ,great hopes were once entertained of accumulator traction on tramways4 ,the storage battery offered a means of escape from all the difficulty and expense of carrying electric mains overhead or underground4 ,by fitting each car with a storage battery1 it could be made an independent self-contained locomotive1 capable of running a certain number of miles until the battery was approaching exhaustion4 ,by providing centres where the batteries could be re-charged--or1 to save time1 replaced by batteries previously charged--a continuous service could be maintained on a tramway system4 ,the advantages of accumulator traction1 apart from the saving in first cost1 are the absence of obstruction and danger from overhead wires1 and of the risk of a general stoppage of the service when the current at the generating station fails from any accidental cause4 ,when accumulators are used1 the conversion of a horse tramway to an electric tramway becomes a very simple matter4 ,all that is required is to erect a generating station and provide each car with a storage battery and electrical equipment4 ,this equipment1 it may be mentioned1 is substantially the same as with ordinary electric cars4 ,the current flows from the accumulator through the controller and the motors back to the accumulator4 ,many trials were made with this system in the early days of electric traction1 but there are no survivals4 ,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 service4 ,the main cause1 however1 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 passengers4 ,lead being one of the heaviest of metals1 this dead weight was a very serious item on accumulator tramcars4 ,it proved to be a fatal item when the attempt was made to run large cars on heavy gradients4 ,the rush of current demanded in starting such cars up-hill was in itself too severe a tax on the delicate structure of the batteries4 ,in practice1 moreover1 the necessity of bringing each car back to the depot for re-charging1 after a limited journey1 proved very troublesome4 ,the more extensive the system and the more frequent the service1 the more troublesome this necessity became4 ,even the most enthusiastic advocate of the storage battery was at last forced to admit that it was not applicable to a system of transport1 which demanded comparatively high speeds with large cars on all gradients and over a range of several miles from the centre of power4 ,after the admitted failure of accumulator tramways1 the storage battery was for some time used only on river launches and small private vehicles4 ,the conditions in both cases--and especially in the former--are very favourable to its operation4 ,on a river launch the weight of the battery is not a serious item1 as it serves to some extent in the place of ballast4 ,launches1 moreover1 are generally required for trips of a limited number of miles up and down the river from the boathouse or charging station of the owner4 ,in contrast with the tramway1 there is no demand for rapid acceleration at starting or for abnormal power at intervals4 ,the batteries discharge slowly and fairly evenly1 and are not subjected to serious vibration4 ,the electrical equipment is extremely simple1 as the motor is fixed on to the propeller shaft and operated by a controller on the deck close to the steering wheel4 ,however1 if economy were the only consideration1 it is doubtful whether the electric launch would have survived against the competition of steam and petrol launches4 ,it has survived because the simplicity of the equipment1 its silent running1 and the absence of heat1 smoke and fumes1 make it the ideal thing for river work4 ,the hire of an electric launch on the ,thames costs more than that of a steam launch1 but plenty of people are willing to pay the additional charge to avoid the drawbacks of steam propulsion on a small vessel4 ,similar considerations underlie the extensive use of electric broughams in cities4 ,such vehicles are required only for travel within a restricted area and on streets where the gradients are seldom severe4 ,their carrying capacity is generally limited to two or four passengers1 so that the batteries do not require to be unduly heavy4 ,a maximum speed of #ab miles an hour is quite sufficient for city streets2 and with careful treatment the batteries can be very economically used and will not deteriorate nearly so rapidly as they would under tramway conditions4 ,considerations of economy1 on the other hand1 do not weigh very heavily with the class of people who use private electric broughams4 ,they are prepared to pay for the best available2 and the electric brougham1 with its noiselessness1 its easy running1 its absence of smell or other nuisance1 is regarded as the ideal which other modes of city transport must do their best to approach4 ,in ,london a certain amount of business has been done for some years in hiring electric broughams for various periods on terms which include current1 maintenance1 garage facilities1 driver's wages1 and all other charges4 ,the convenience of such an arrangement to the hirer need not be emphasised1 since what is wanted in this case is a vehicle which is always ready at a telephone call4 ,but the system has another important advantage1 which bears upon the economic prospects of accumulator traction4 ,by retaining the vehicles under its control the hiring company not only centralises the arrangements for storing and re-charging1 but it is able to take care that the batteries are properly treated4 ,just as the success of the surface-contact system depends on minutiae of design1 so the success of accumulator traction depends upon minutiae of treatment4 ,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 nuisance4 ,consequently the success of this class of business depends upon an organisation which permits of constant supervision over every vehicle and every driver4 ,a good deal of ingenuity has been exercised upon the electrical equipment of broughams2 and it is probable that further improvements will be made4 ,in some cases the front axle is driven by the motor2 in some cases the back axle4 ,the earliest cars used toothed-wheel gearing in order to reduce the speed of the small fast-running motor4 ,improved types on this principle still exist1 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 means1 without any intermediate gearing4 ,in addition to these improvements1 the storage battery itself has made a distinct advance in design and construction4 ,it is more efficient1 more durable1 and more reliable now than ever it was before4 ,the closer attention given to its treatment tends in the same direction2 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 conditions4 ,the conditions being the variable factors in the problem1 and being in large measure determinable by choice1 it is rather remarkable that the engineers and financiers should have selected1 at the outset1 the very conditions which were least suited to the peculiarities of the accumulator4 ,the attempt to adapt battery traction to tramway work is a conspicuous case in point1 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 elsewhere4 ,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 propulsion4 ,the electric omnibus has many of the drawbacks of the storage-battery tramcar1 but they are not so serious in the case of an urban service1 adequately met by small cars running at moderate speeds on short routes with moderate gradients4 ,it is possible that if recent metropolitan electric omnibus enterprises had been as happy in their finance as in their engineering1 they would have succeeded well enough4 ,but even in their engineering they had to meet great difficulties4 ,they sought to protect themselves against excessive costs by entering into maintenance agreements with the makers of the batteries2 and although the terms of these agreements were satisfactory enough1 their validity depended on careful treatment of the batteries by the drivers of the cars--a matter which it is rather difficult to guarantee4 ,moreover1 the number of omnibuses put on the road was so small that the garage costs and other standing charges were proportionally very heavy4 ,with a larger fleet and with efficient organisation1 much better results might have been achieved in spite of the inherent difficulties of the situation4 ,although the electric cab has the advantage of being a smaller vehicle and therefore more adapted to economical propulsion by storage batteries1 the conditions of the cab service are not at all favourable to the system4 ,the essential feature of a cab is that it should be available anywhere1 to go anywhere at a moment's notice4 ,an accumulator-driven vehicle1 on the other hand1 is tied by an invisible cord to the charging station4 ,even if charging stations were multiplied enormously1 the electric cab would have no real freedom of action1 since several hours are required for the process of re-charging4 ,we have only to compare the limitations of the electric cab with the freedom of the petrol cab 7which can renew its supply of petrol in a minute or two at any motor depot7 to realise that the roving commission is not at all suited to the former4 ,in #ahii a very bold effort was made to establish an electric cab service in ,london4 ,to inaugurate the service a procession of the cabs was formed1 but it excited more ridicule than serious interest4 ,the clumsy appearance of the cabs was against them2 and their behaviour was not satisfactory enough--as to speed and reliability--to overcome the first unfavourable impressions4 ,they soon disappeared1 to add another failure to the long list of disappointments in connection with accumulator traction4 ,the private electric automobile remains1 however1 because it has been organised under conditions which suit the peculiarities of the storage battery4 ,its survival1 in conjunction with the failure of a similar means of transit for tramway1 omnibus1 and public cab services1 has pointed to another direction in which the electric automobile should be a commercial possibility4 ,that is1 in connection with the local distribution of goods from large stores and other centres4 ,the ,united ,states have given a very distinct lead in this matter4 ,in ,new ,york1 ,chicago1 ,washington1 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 tons4 ,no doubt the local cost of other means of transport has something to do with this ,american development1 which has1 moreover1 been strongly supported by the companies which supply electricity to the public4 ,but the fundamental reason lies in the special character of the service demanded4 ,the vans belonging to a large store all start from a certain point and return to it after journeys of limited range4 ,owing to the period occupied in loading up1 and also to the pre-determined hours of most of the deliveries1 there is no difficulty about affording the time required for re-charging the batteries1 or in arranging each journey so that the vehicle returns before the batteries are exhausted4 ,with a standardised fleet of vehicles1 it is possible to remove the discharged batteries and replace them with charged ones in a few minutes4 ,the whole arrangement1 in fact1 is like a private automobile garage1 with the advantage that the probable demand can be forecast with a somewhat greater degree of certainty4 ,steam and petrol-driven wagons run most economically on long steady journeys at fairly high speeds1 and the electric automobile does not attempt to compete with them on these lines4 ,but it offers competition within city limits for door-to-door delivery2 and its prospects are particularly good for light parcel service1 where the horse is still maintaining its position against the petrol vehicle4 ,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 rivals4 ,apart from the necessity of careful organisation1 the main essential of success in electric automobile work is a supply of cheap electricity4 ,owners of private electric launches have to pay anything from #h;d4 to #bs4 #f;d4 per unit for re-charging their batteries1 but these high prices are due to the intermittent character of the demand and also 7in some cases7 to the cost of providing machinery to supply current at special pressures for particular launches4 ,an electric automobile garage1 situated close to a public generating station and offering a larger and more regular demand1 will of course obtain current much cheaper4 ,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 demands4 ,in the metropolitan borough of ,marylebone1 for instance1 an electric garage may obtain current during the small hours of the night at #a_/b;d4 per unit1 which is half the standard rate for power purposes4 ,this low price is offered because there is otherwise practically no demand at all for electricity during these hours4 ,if1 therefore1 a garage arranges--and the arrangement is quite feasible--to charge its batteries overnight1 the power bill may be divided by two4 ,the electric automobile has been used to some extent as a touring car1 but although journeys up to #ajj miles have been performed on a single charge1 the time occupied in re-charging1 and the difficulty of finding convenient charging stations1 are fatal to any development in this field4 ,,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' systems4 ,at one end of the chain1 electricity plays an important part in supplying power to drive the car4 ,at the other end1 electrical apparatus is introduced merely as a form of transmission gear between the petrol engine and the driving axle4 ,the reason for attempting the petrol-electric combination will be most readily understood by considering the latter arrangement first4 ,the petrol engine is a high-speed engine1 capable of working most satisfactorily when it runs at a uniform rate with a constant load4 ,on the other hand1 the speed of the driving axle of a car varies from a very much lower speed down to zero4 ,it is therefore necessary1 when driving a vehicle with a petrol engine1 to arrange some forms of variable speed-reducing transmission gear between the engine and the driving axle4 ,the problem is further complicated by the fact that the petrol engine is irreversible1 has practically no 'starting torque1' and has a very slight overload capacity4 ,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 car4 ,as the speed of the car rises1 there have to be successive changes of gear4 ,these difficulties are1 of course1 accentuated when dealing with the heavy weight of an omnibus4 ,illustration3 ,fig4 #i4 ,elevation and plan of a petrol-electric motor omnibus equipped by ,w4 ,a4 ,stevens1 ,ltd4 ,directly behind the front wheels is the petrol engine1 driving a dynamo through a flexible coupling4 ,the dynamo supplies current to the motor directly behind it2 and the motor drives the rear wheels through a cardan shaft4 ,the transmission of power between the engine and the shaft is electrical at all speeds4 ,practically all the troubles with petrol motor omnibuses have resided in the gear2 and even the most ardent enthusiast for the all-electric faith must admit that the motor engineer has overcome these troubles 7in great part if not wholly7 with remarkable skill and ingenuity4 ,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 substitute4 ,by coupling the engine direct to a dynamo and by using the current so generated to drive variable-speed motors geared to the driving axle1 the electrical engineer hoped to get better working results from the petrol motor than could be obtained with any mechanical transmission gear4 ,the most conspicuous advantage1 apart from the quietness of running at all speeds1 lies in the ease and smoothness with which the petrol-electric motor can start and gain speed4 ,in this respect the combination system is practically on the same level as 7or even superior to7 the electric tramcar or the electric automobile4 ,there is an entire absence of the jerks and jarring noises which usually accompany the starting of a motor omnibus4 ,the same facility of control is of advantage in adjusting speed to suit the other traffic on the road1 and also in negotiating hills4 ,in one class of petrol-electric vehicles the electric transmission gear is continuously used4 ,in another1 it is used at all speeds except the highest1 when the engine is coupled directly 7by a magnetic clutch7 to a mechanical driving gear4 ,in a third class the arrangement is more complicated1 as it involves the use of storage batteries as an auxiliary to the power provided directly by the petrol engine4 ,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 negotiated4 ,at ordinary speeds on level roads the surplus power produced by the engine goes to charge the battery4 ,the ',automixte' type is peculiar in using the mechanical transmission gear all the time4 ,the dynamo coupled to the engine supplies current to a small battery when surplus power is available2 the same dynamo may be driven as a motor by current from the battery when such assistance is wanted at starting or on steep hills4 ,the electric part of the equipment thus acts first as a generator and then as a motor1 the change taking place automatically4 ,these different petrol-electric devices are very attractive from the engineering point of view1 but at the present time it is uncertain whether they will realise the hopes of their inventors4 ,the additional weight of the electric equipment is against them2 and in some cases there appears to be a lower all-round efficiency4 ,so that the motor-omnibus world1 as a whole1 continues to fix its faith upon the improved forms of mechanical transmission4 ,the underlying idea of the petrol-electric system has1 however1 been suggested for marine propulsion with a somewhat better prospect of success4 ,there is a partial analogy between the conditions of motor omnibus working and of ship propulsion with turbines4 ,the steam turbine is1 like the petrol engine1 essentially a high-speed machine4 ,the screw propeller1 on the other hand1 works most efficiently at low speeds4 ,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 slowly4 ,illustration3 ,fig4 #aj4 ,diagrammatic section of a steamship which has been 'converted' from the ordinary method of propulsion to the ',paragon' system of electric main marine propulsion4 ,the reciprocating engine has been replaced by a steam turbine1 coupled direct to an electric generator which supplies current to a motor attached to the propeller shaft4 ,the tests carried out with this vessel will indicate the advantages of the electric method of propulsion even with the usual long length of shaft4 ,the vessel has a gross tonnage of #abda1 and its speed is #i knots4 ,the engines replaced ran at #gh revolutions per minute and gave #ejj brake horse power4 ,the turbine now installed runs at #bejj r4p4m41 and develops #fcj brake horse power4 7,illustration reproduced by courtesy of ,the ,electrician47 ,the gulf between the two has been narrowed by the improved design of propellers4 ,some engineers assert that continued improvements will bridge the gulf completely4 ,others have sought the solution in the same way as the motor engineer--by the use of mechanical change-speed gears4 ,the suggestion has also been made to employ hydraulic gear as an intermediary2 and in some recent vessels reciprocating engines with comparatively low-speed turbines driven by exhaust steam have been adopted4 ,in the electric system the turbine is coupled direct to an electric generator and may run continuously at the highest economical speed4 ,the propeller shaft may be quite short and is driven by a slow speed motor connected by cables to the generator4 ,various arrangements for controlling the supply of current to the motor 7with appropriate design of generator and motor7 have been devised by ,mr ,durtnall1 ,mr ,mavor1 and other workers in this field2 but whatever the details of these arrangements may be1 they all give a wide range of speed both ahead and astern4 ,the direct drive with the steam turbine has really only one speed--full speed ahead2 and as the turbine is irreversible1 'astern' turbines have to be installed in addition4 ,these limitations and complications are removed entirely when electrical transmission is adopted4 ,moreover1 the electric system can be so arranged that the control gear may be operated from the bridge itself4 ,the facility in manoeuvring is1 in fact1 so marked that it would recommend electric marine propulsion even if that system offered no advantages on the score of economy in weight1 space1 and steam consumption over the existing systems4 ,the steam turbine1 it may be noted1 has been adopted so far only in high-speed vessels2 and it is generally recognised that its extension to vessels which run at #ab or #af knots depends upon its adaptation to slow-speed propellers4 ,advocates of electric marine propulsion claim that they hold the most efficient solution of this problem4 ,it may also be pointed out that a considerable section of marine engineers look forward to the use of internal combustion engines 7driven by oil or gas7 on board ship4 ,for naval purposes especially it would be a great advantage to do away with funnels and so leave the decks more free for gun mountings4 ,as internal combustion engines are irreversible1 the electric system offers a means of escape from a fundamental drawback to their use at sea4 ,here again the perfection of manoeuvring power1 especially with twin screws 7either of which may be controlled from the bridge through a wide range of speed ahead or astern71 gives the electric system a strong claim for consideration by the naval authorities4 ,it is hardly necessary1 except as a matter of curiosity1 to refer to the suggestions made1 from time to time1 of accumulator-driven ocean steamships4 ,some wonderful pictures have been published of large vessels with tons of ballast in the form of storage batteries4 ,they are likely to remain in this ideal condition1 for although the driving of a large vessel by stored electricity is quite possible1 it is also about the most expensive method which has ever been proposed4 ,electric power from storage batteries has been used as an auxiliary in the propulsion and manoeuvring of submarines4 ,in aerial navigation electricity has so far been employed to a very limited extent4 ,small airships have been designed to carry electric accumulators connected with various motor-driven propellers for raising1 lowering1 going ahead or astern1 and steering4 ,the switches which control the passage of the current to these propellers are connected with a wireless telegraph receiver1 so that each operation may be started or stopped by a particular ether wave or series of waves4 ,demonstrations of such 'wireless-controlled' airships have been given in theatres2 their field of usefulness1 if any1 is in connection with war on land or sea4 ,whether they will have any better fate than other devices for dropping bombs over the enemy's camps or ships remains to be seen4 ,one inventor has1 ,i believe1 suggested a means of direct electrical propulsion for aeroplanes1 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 manoeuvring4 ,as yet1 however1 the probability of electricity being applied to locomotion in the air as well as on land and on sea is somewhat remote4 ,,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 directions4 ,such development as they feel capable of making under present legislative conditions is only by proxy and tentatively1 with the aid of the trolley omnibus4 ,electric railways1 however1 have still many worlds to conquer4 ,they are now in much the same position as electric tramways held about the year #ahif4 ,that is to say1 they have already given practical proof of their capabilities and enabled engineers to point out the directions along which they are certain to develop4 ,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 time4 ,for main line traffic the possibilities of using electricity are as yet only an article of faith among electrical engineers4 ,although the earliest experiments in electric traction were made in the railway form1 the first electric lines could hardly be regarded as railways in the ordinary sense4 ,they were really light railways1 in which the traffic conditions approximated to those of tramways4 ,the routes were short1 the cars small1 and the traffic of modest dimensions4 ,they contained the germ of both the tramway and the railway2 but1 in the case of the railway1 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 solved4 ,the fact that the first electric railway in the ,united ,kingdom was constructed at the ,giant's ,causeway 7in #ahhc7 is significant4 ,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 facilities4 ,in #ahhe another electric railway deriving its energy from water-driven turbines was built between ,bessbrook and ,newry4 ,at that period it was considered that waterfalls provided the only really feasible source of cheap electricity on a large scale4 ,even yet the impression survives that electric power stations using steam cannot produce current so cheaply as those which 'harness' waterfalls4 ,many people1 in fact1 are inclined to attribute the comparative backwardness of electrical development in ,great ,britain1 not to legislative conditions1 but to the lack of large waterfalls4 ,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 ,bessbrook4 ,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 water4 ,the idea that a waterfall provides power 'for nothing' is one of those superficial conceptions which make the hardiest of fallacies4 ,to 'harness' a waterfall requires a heavy expenditure of capital on conduits1 pipe-lines1 dams1 and other works4 ,the interest upon that capital is a heavy item1 apart from the cost of maintenance and repairs4 ,waterfalls are situated in mountainous country1 generally remote from the centres of industry2 the water-power station1 therefore1 has to face the cost of transmission mains and the loss of energy involved in conveying the power to the place where it is wanted4 ,further1 waterfalls and the adjacent ground belong either to individuals or to the ,state2 and payment is generally exacted for the right to use them4 ,all these items have to be covered in the price charged for current to the public or to railway undertakings4 ,nature may provide the 'head' of water 'free1' but man has to spend money in utilising it1 just as he has to do in mining and in obtaining heat from the coal which is also provided 'free4' ,anything which is obtained 'for nothing' is generally worth nothing4 ,the full economies of generating electricity by steam power are not1 however1 realised until business is done on a large scale4 ,as the first essential of a successful electric railway is a plentiful supply of cheap power1 development from the experimental stage of ,portrush had to wait until engineers mastered the art of producing electricity from large generators4 ,they gained the necessary experience with electric tramways and in electric lighting4 ,we have seen how1 as regards tramways1 legislation delayed and hampered progress4 ,a similar cause was at work in connection with electric lighting4 ,in #ahhb an ,act was passed regulating electric lighting on lines modelled upon the principles of the ,tramways ,act1 #ahgj4 ,capitalists declined to work under this ,act2 and it was not until after #ahhh1 when the ,act was amended1 that any money could be found in ,great ,britain for electric lighting schemes4 ,this delay was a serious handicap not only to electric lighting but to the business of ,british electrical manufacturing1 as there was1 comparatively speaking1 no demand for electrical plant for over six years4 ,meanwhile1 matters had been advancing on normal lines in other countries2 and when the demand came at last1 the manufacturers on the ,continent and in ,america were the only ones organised and ready to meet it4 ,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-day4 ,they also serve to explain the prominent part which ,american and ,german firms took in electrical developments here4 ,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 #ahij1 and did not attain to any conspicuous growth until the beginning of the twentieth century4 ,until after #ahij the only electric railways in ,great ,britain taking power from steam dynamos were those at ,brighton ,beach1 ,ryde ,pier 7,isle of ,wight7 and ,southend ,pier1 opened in #ahhc1 #ahhf and #ahij respectively4 ,these were all1 of course1 of short length4 ,the ,brighton ,beach railway1 designed and constructed by ,mr ,magnus ,volk1 was a unique piece of work4 ,the rails were laid on heavy concrete blocks below high-water mark2 and the cars were platforms raised on a light iron structure4 ,power was conveyed to the cars from wires hung on posts like the standards of a tramway on the trolley system4 ,the unusual sensation of travelling over the water was enjoyed by hundreds of people until the difficulty of maintaining the track 7owing to the erosive action of the waves7 led to the railway being abandoned and another line of more ordinary character being laid on the level of the undercliff roadway4 ,the first indication of the genuine electric railway movement was given in #ahic1 when the ,liverpool ,overhead ,railway was opened4 ,this line was constructed to afford communication along the line of docks fringing the ,mersey4 ,the track was carried on a continuous bridge in order to avoid obstruction between the docks and the streets behind2 and being overhead1 there were serious disadvantages attached to the use of steam locomotives4 ,electric locomotives were therefore employed4 ,in this case1 it should be noted1 electricity was not adopted because it was more economical or efficient than steam4 ,the reason lay with the peculiar situation of the railway4 ,a similar reason decided the promoters of the ,city and ,south ,london ,railway to try electric locomotives on their line4 ,this railway1 which was opened in #ahij1 was the first deep level or 'tube' railway in the world4 ,moreover1 it was constructed and equipped throughout by ,british engineers1 and at a time when the art of tunnelling was much less advanced than it is now4 ,in the later and more imposing development of tube railways in ,london1 the foresight and enterprise displayed by the pioneers of the ,city and ,south ,london ,railway are apt to be overlooked4 ,it was1 however1 the success of the original line from the ,monument to ,clapham which made it possible to raise capital for the ,central ,london ,railway 7opened in #aijj7 and for the extensive tube railway system organised by the ,underground ,electric ,railways ,company of ,london4 ,on a deep-level railway1 steam is1 of course1 out of the question4 ,even on the old ',underground1' built close to the surface and furnished with frequent openings at the stations1 and by means of ventilating shafts1 the atmospheric conditions were abominable4 ,the sulphurous fumes were indeed recommended for asthma and other complaints1 but on a tube railway they would have been sufficient to cure every human ailment4 ,therefore the choice lay between electric traction and haulage by cables1 compressed air1 or some other innocuous system4 ,within these limits electricity was chosen on its merits4 ,the first railway in ,great ,britain to undertake conversion was one in which both the physical and economic troubles were exceptionally serious4 ,the ,mersey ,railway is little more than a tunnel under the river1 and it is distinguished by heavy gradients and by the continuous necessity of pumping out the water which drains into it4 ,with steam traction the difficulty of ventilating the tunnel was an added trouble4 ,owing to these various causes the working expenses were abnormally heavy1 and led ultimately to a receivership4 ,electric traction was adopted as the only possible cure4 ,the pumping and ventilation arrangements were both reorganised for electric power2 and the trains were equipped with electric traction on the 'multiple-unit' system1 an arrangement--to be described in the next chapter--which is well suited to the economical handling of steep gradients4 ,the practical result was a great increase in traffic1 with a marked decrease in the proportion of expenses to receipts4 ,no other ,british railways1 happily1 were in so desperate a condition as the ,mersey line1 but all of them were1 at the end of last century1 feeling the effect of certain disquieting tendencies4 ,these tendencies were most marked in connection with suburban and short-distance inter-urban traffic1 which is quite distinct in character from the main-line traffic4 ,we talk glibly enough of railway traffic as if it were a unity1 but it is clear that very different considerations govern the traffic on a main line between1 say1 ,london and ,glasgow1 and those which control the traffic on ,london suburban routes or on a railway connecting the adjacent towns of the ,potteries4 ,some railways have to deal with all three classes at the same time and occasionally on the same lines of rails4 ,electric traction has1 so far1 made itself felt only where the suburban or similar inter-urban traffic has been separable from the main line traffic4 ,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 companies1 but it did not always do so4 ,competition between the various companies led to a reduction in fares2 ,parliament1 by establishing workmen's fares1 forced the companies to carry an ever-increasing number of passengers at a loss1 or at least without profit2 wages tended to increase and hours of working to decrease--both affecting the cost of operation2 rates and taxes became heavier and heavier with the growth of municipal expenditure2 and a higher standard of comfort and efficiency was demanded by the public4 ,in some instances the situation was aggravated by the competition of electric tramways along routes parallel to the railways4 ,this competition was limited to point-to-point traffic1 its maximum range being about three miles2 but it was a grievance against which the railway companies protested very loudly1 especially when the tramways were owned by local authorities to which the railways paid large sums in rates4 ,the general effect of all these factors was to reduce the margin of profit on which the railways were working4 ,we have seen1 in the case of tramways1 how easy it is for a slight change in a frequently-recurring expense to have a serious effect in the aggregate4 ,railways are in much the same position2 and the various influences at work upon the suburban traffic brought them face to face with the importance1 if not the necessity1 of finding some means of dealing with larger volumes of traffic on a basis more economical than that provided by steam locomotives4 ,this means they found in electric traction2 but it may be noted that even railway engineers took some time to realise exactly what electric traction offered them4 ,they were looking for something to reduce their annual expenses2 and when they made calculations about electric traction they found that1 when the expense of providing the electrical equipment was taken into account1 the total cost of hauling the trains electrically on the existing schedule might be greater instead of less than the cost of steam haulage4 ,they were therefore inclined to look upon the economic benefits of electric traction as an illusion4 ,in course of time1 however1 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 account4 ,its essential purpose is to increase the volume of traffic4 ,from the public point of view this is very much more valuable4 ,passengers are not directly concerned with means of reducing working expenses1 but they are closely interested in the improvement of the frequency and speed of the service4 ,the adoption of electricity on suburban lines has really been dictated by the demand for increased facilities4 ,at the 'rush' hours of the morning and evening1 when the great tide of workers flows and ebbs1 the capacity of the steam lines was taxed to the utmost4 ,and with the growth of population the difficulty of running sufficiently frequent trains became almost insuperable4 ,apart from these particular necessities1 the general features of railway economics point to the supreme advantage of increasing the volume of traffic in every possible way4 ,in a railway1 as in a tramway1 the preponderating item is the cost of construction and maintenance2 and unless a certain minimum of traffic is carried1 the most economical working in the world will not secure a profit4 ,the standing charges fall upon the idle hours as well as upon the busy2 for every minute that a line of rails stands empty there is a loss of money4 ,railway progress depends upon reducing the proportion of idle hours2 and that can only be done where there is scope for the growth of traffic1 and where there is means--such as electric traction--of dealing with that growth on an economical basis4 ,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 conditions4 ,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 ,railway4 ,illustration3 ,fig4 #aa4 ,an electric train on the ,metropolitan ,district ,railway1 equipped by the ,british ,thomson ,houston ,company4 ,the front and rear cars and one intermediate car are equipped with electric motors1 all controlled from the 'cab' at the end of the train4 ,the controller handle may be seen close to the nearest window of the first car4 ,the rail immediately in front of the foot of the guard is the conductor rail which conveys the current to the train4 ,the rail between the track rails carries the return current4 ,throughout the steam age the finance of the ,district ,railway ,company was as unattractive as the physical conditions of the railway itself4 ,no dividend was ever paid on the ordinary shares2 and even with the growth of ,london there was little prospect of any dividend ever being paid4 ,when--about ten years ago--the late ,mr ,c4 ,t4 ,yerkes came over from ,america and obtained a controlling interest in the ,district ,railway ,company with a view to converting it to electric traction1 he was regarded as a philanthropic enthusiast4 ,many of the shareholders themselves were reluctant to give their assent to the change2 they preferred to bear the ills they knew than fly to others which might be introduced by an ,american financier4 ,but ,mr ,yerkes and those who worked with him had something more in view than the improvement of traffic on the ,district ,railway4 ,they acquired control of several tube railway schemes and obtained powers for new lines1 so as to organise a comprehensive system of underground electric transport in ,london4 ,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 traction4 ,the constructional work occupied several years2 and after the lines were opened one by one1 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 ,railway1 the ,metropolitan ,railway 7closely linked with the ,metropolitan ,district7 and the ,city and ,south ,london ,railway4 ,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 trains4 ,from these points of view the organisation of the network of lines comprehensively known by the title of ',underground' is certainly unsurpassed4 ,the difficulties which had to be overcome in this great work were enormous1 but there has been no break in the thread of progress4 ,the 'tubes' are paying dividends which1 though modest1 are an encouragement to further developments4 ,the finance of the ,district ,railway has lost its element of chronic despair4 ,considered as a whole1 the results prove that where there is the potentiality of large traffic1 electricity is the instrument which must be applied4 ,during the steam days1 the most crowded part of the ,district ,railway 7the ',inner ,circle'7 carried a maximum of #af trains per hour4 ,with electric traction that figure has been raised to #dj trains per hour4 ,and the remarkable thing is that with each increase in the service the traffic grows4 ,many people welcomed the electrification of the ,district as a measure of relief from the overcrowding on the steam trains during the busy hours4 ,but with a service of trains more than doubled in frequency and also increased in capacity per train1 overcrowding continues and the 'straphanger' has become an established institution4 ,it may be accepted as substantially proved that1 on suburban and inter-urban railways in populous districts1 electric traction is a means of increasing traffic and diminishing the proportion of working costs4 ,moreover1 these results have been achieved in conjunction with substantial reductions in fares and with marked improvements in the comfort of travelling4 ,the engineering aspect of these changes has now to be considered4 ,,chapter ,,xiii ,,electric ,,railways ,,from ,,the ,,engineering ,,point ,,of ,,view ,when electric railways were first considered1 the natural tendency of engineers was to follow the existing model and merely substitute electric locomotives for steam locomotives4 ,in point of fact1 however1 the engineering method now adopted is an evolution from the tramway model1 not from that of the typical railway4 ,a certain advantage was1 of course1 to be gained by replacing steam locomotives by electric ones4 ,the greater 'starting torque' of the electric locomotive enables it to get a train up to full speed more quickly2 and the capacity of the electric motor for taking heavy overloads assists the electric train in surmounting heavy gradients4 ,some advantage was also gained by producing all the power at a central source1 instead of having a large number of steam locomotives1 which are really power stations on wheels4 ,but the electric locomotive had still to be made heavy enough to get sufficient grip of the rails2 it had to haul its own dead weight2 and it had to be made powerful enough to tackle a full-sized train on the steepest gradient with its complement of passengers1 although the general demand upon it might be considerably less than that maximum4 ,the electric locomotive1 in short1 was an advance upon the steam locomotive1 but it did not get past the essential drawbacks of the locomotive system4 ,a locomotive is most economical when hauling full trains for long distances at a uniform speed2 it is essentially a long-distance machine4 ,the first demand for electrification came1 however1 from suburban railways1 where the stations are close together and where1 therefore1 the speed is constantly varying from zero up to a maximum and back to zero again4 ,the traffic also fluctuates between extreme limits2 and there is obvious waste in having to run heavy locomotives and trains backwards and forwards during the slack hours4 ,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 traffic4 ,a step in the right direction was taken when the locomotive equipment was placed on a car1 thus utilising the weight of the passengers to increase the adhesion on the rails4 ,but the full advantages of electric traction were not realised until what is known as the 'multiple-unit' system was adopted4 ,the idea underlying this system is quite simple4 ,if1 instead of concentrating the motive power on a single locomotive or driving unit1 we distribute it among the cars forming a train1 we get the multiple-unit system4 ,an electric tramcar and a trailer attached to another tramcar and trailer1 with a third tramcar behind1 would form a model for a multiple-unit train4 ,by connecting the electrical equipments on the three tramcars--front1 middle1 and rear--it would be possible to control the train from either end or from the middle4 ,this is the principle upon which all the electric railways in ,great ,britain are now worked1 with the exception of the ,city and ,south ,london ,railway1 where locomotives are still used and where the trains are comparatively short and light4 ,it will be seen that each multiple-unit train is readily divisible4 ,a single motor car may be run1 or a car with one or two trailers1 or a long train made up of as many motor cars and trailers as the platforms will accommodate4 ,and whether the trains are long or short1 the power absorbed is in proportion to the length of the train and the load of passengers4 ,by this simple means power is economised1 and the railway engineer is able to reduce the proportion of idle rolling stock4 ,the adjustment of the length of trains to the fluctuations of the service is made easier by the absence1 in the multiple-unit system1 of the necessity of shunting at the termini4 ,as a multiple-unit train can be controlled from either end1 a more frequent as well as a more flexible service can be run4 ,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 operation4 ,with an electric train on the multiple-unit system1 no more time is lost than the few seconds necessary for the driver to walk from the front of the train to the rear1 which then becomes the 'front4' ,no lines have to be kept open for shunting locomotives1 so that the available accommodation for trains is considerably increased4 ,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' traffic4 ,electric traction therefore offers them an improvement of enormous value without the expenditure of a penny on station alterations4 ,the crowning advantage of electric traction lies1 however1 in the more rapid acceleration which it affords4 ,we have already seen how important this item is on tramways4 ,it is still more important on suburban railways1 where a high average speed1 in spite of frequent stops1 is a vital matter4 ,on the ,district ,railway the rate of acceleration in the old steam days was about #f inches per second per second4 ,it was1 in fact1 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 station4 ,with electric traction the rate of acceleration has risen to about #ah inches per second per second4 ,on the ,liverpool ,overhead ,railway a rate of #cf inches per second per second was reached in certain tests4 ,heavy starting currents are1 of course1 necessary to bring a train from rest to full speed at such a rapid rate1 but it is quite possible for the electrical engineer1 without being unduly extravagant in current1 to accelerate a train more quickly than the passengers would find comfortable4 ,the practical result of rapid acceleration 7combined with rapid braking7 is not only to give a higher average speed but also to enable a more frequent service to be run4 ,owing to the block system on railways it is impossible for trains to follow each other closely in the manner of tramcars2 and it is therefore of cardinal importance that no train should occupy a block for one second more than is necessary4 ,rapid acceleration becomes all the more important in this respect because of the difficulty of setting down and picking up passengers quickly4 ,this difficulty is overcome in part by using saloon carriages with middle and end doors1 in place of compartment carriages4 ,at first the ,district ,railway tried to help matters by operating these doors pneumatically1 but the mechanism became unpopular after a number of late-comers had been pinched by closing doors4 ,the management has reverted to hand operation2 and it has probably achieved more by educating the public to move quickly than it would have gained with its too-perfect mechanical system4 ,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 railway4 ,thus the passenger1 as well as the service1 has been 'speeded-up4' ,the more frequent service of trains with a higher average speed would not have been possible1 however1 without an improvement upon the old methods of signalling4 ,there is no need to dwell upon the weakness of the human element in railway signalling2 and it will be clear even to the layman that the strain of handling traffic with a headway of one minute and a half1 or less1 would be more than men could stand4 ,automatic signalling had therefore to be adopted to obviate the risk of disaster4 ,each train1 as it leaves a block or section1 'clears' the signals for that block2 and when any train attempts to enter a block against signals1 the current is automatically switched off and the brakes applied4 ,the system is so perfect that1 in spite of the enormous traffic worked under it1 there has been no failure and no accident4 ,it is1 of course1 costly to install2 and its cost can be justified 7financially7 only when the traffic is very heavy--that is to say1 when the conditions make it almost a necessity4 ,the supply of electric power to electric railways is organised on practically the same lines as in the case of tramways4 ,that is to say1 current is generated at a central station1 transmitted at high pressure to various sub-stations1 and supplied from there at working pressure through 'feeders' to each section of the system4 ,in the case of the ',underground' system1 most of the power is taken from a single huge electric station at ,chelsea4 ,current from that station drives trains as far west as ,wimbledon1 ,hounslow1 and ,ealing1 as far north as ,highgate and ,golder's ,green1 and as far east as ,barking4 ,this is a magnificent example of the concentration which gives economy4 ,if each of the underground railways forming the system had erected its own generating station1 the total initial outlay1 on land1 buildings1 and machinery1 would have been greater1 and the cost of current would have been higher1 owing to the smaller output and the more irregular demand which a single railway affords4 ,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 day4 ,the ,chelsea power station is nearer the ideal than a smaller one supplying a short railway could be4 ,and a station of the latter class is1 it may be noted1 nearer the ideal than the arrangements on a steam railway1 where the sources of power are scattered in hundreds of locomotives4 ,the concentration of power is therefore one of the many factors which have enabled electric railways to give a vastly improved service at lower fares4 ,with two exceptions--to be considered in the next chapter--the electric railways of ,great ,britain are constructed on the 'third-rail' system4 ,they are thus a reversion to--or1 rather1 a survival of--the original type adopted by ,siemens in #ahgi4 ,the 'third-rail' is carried on insulators a few inches outside the track rail2 and the motor cars are provided with a 'brush' or 'shoe' which slides along it and collects the current4 ,in the centre of the track there is generally a second insulated rail to carry the return current1 as it is more convenient1 under railway conditions1 to have a conductor independent of the track rails than to follow the tramway plan of using the rails 'bonded' together4 ,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 it4 ,the board is placed high enough over the rail to allow the shoe to pass freely4 ,as regards the motor equipment on the cars1 tramway models have been followed very closely4 ,the 'series-parallel' system of control is again adopted in order to get the high starting torque which gives rapid acceleration with moderate current consumption4 ,the course of the current is again from the live rail1 through the controller1 through the motors1 and thence to the return rail4 ,the controller itself is more or less on the tramway principle2 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 controller4 ,this is done by connecting the controllers electrically and using electric power so that they all work in unison4 ,some companies use1 for this purpose1 compressed air controlled by electricity instead of electric power alone1 but in both cases the principle is essentially the same4 ,considered as a whole1 the difference between a tramway and an electric railway on the third-rail system is a difference in degree1 not in kind4 ,the traffic is greater and the speeds higher1 but both serve the purposes of comparatively short-distance transit4 ,indeed1 within certain limits they compete with each other4 ,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 railways4 ,,chapter ,,xiv ,,electric ,,traction ,,on ,,main ,,line ,,railways ,on tramways1 automobiles1 and 'third-rail' lines1 the electric current used belongs to the type described as 'continuous' or 'direct1' because the flow is always in the same direction4 ,the other type of current is known as 'alternating1' as it flows backwards and forwards many times per second4 ,there are several kinds of alternating current--single-phase1 two-phase1 three-phase1 and polyphase--each produced from generators designed in a particular way4 ,it is not possible to give any adequate account of these different kinds of alternating current without going rather deeply into the theory of electricity4 ,the ultimate practical point is that in transmitting alternating currents the circuits increase in number with the phases4 ,thus1 three-phase current requires three wires1 two-phase current three or four wires1 and single-phase current a single circuit like that of continuous current#a4 ,illustration3 ,fig4 #ab4 ,photograph of a train on the electrified section of the ,london1 ,brighton and ,south ,coast ,railway4 ,the overhead wire is suspended from cables stretched between insulators1 and current is conveyed from it to the trains through a 'bow' which slides along its lower side4 ,the photograph is taken from the rear part of the train4 ,the front and rear cars are both equipped with electric motors4 ,where current has to be conveyed economically over long distances1 it is generally done in the form of alternating current at high pressure4 ,for instance1 the transmission from a tramway power station to the sub-stations is almost uniformly by three-phase current at1 say1 #ejjj volts4 ,when it reaches the sub-station1 it is 'transformed' down to the working pressure of #ejj volts and 'converted' from alternating to continuous current by means of rotary machinery4 ,the transforming is done by a stationary piece of apparatus similar in principle to the familiar induction coil4 ,an induction coil takes current at a few volts from a battery into its primary circuit and transforms it1 by induction in the secondary circuit1 into current of high enough voltage to give a long spark4 ,a transformer can be designed to 'step-up' or 'step-down' the pressure according to the requirements of the case4 ,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 ,london1 ,brighton and ,south ,coast ,railway4 ,the ,morecambe and ,heysham section of the ,midland ,railway is also equipped on the single-phase system4 ,most of the earliest electric railways on the ,continent derived their power from waterfalls and had to transmit it for a considerable distance4 ,three-phase current at high pressure being adopted for this purpose1 the ,continental engineers set to work to find some means of utilising the high-pressure three-phase current directly4 ,they did this by carrying the three wires on poles alongside the railway track1 and using three 'bow' collectors 7in place of trolley wheels7 to convey the current to transformers on the motor cars or locomotives4 ,in these transformers the current was brought down to working pressure and then led to motors designed for three-phase current4 ,an immense amount of technical ingenuity was exercised in developing this system2 and when the ,metropolitan ,railway decided to follow the ,district in electrifying its lines1 a three-phase system was proposed4 ,as the ,metropolitan and ,metropolitan ,district companies share the working of the ,inner ,circle1 it was necessary that both should adopt the same system4 ,the result was that the question between three-phase and continuous current working had to go to arbitration4 ,after a long discussion of masses of technical evidence1 ,mr ,lyttelton1 the arbitrator1 decided that the direct current system was better suited to the conditions of traffic on an underground railway in ,london4 ,the wisdom of that decision will not be questioned now4 ,three-phase motors do not give the rapid acceleration which is so urgently required on suburban lines2 there are complications in speed control2 and the necessity of having three overhead conductors is also a serious drawback4 ,for comparatively long-distance traffic with few stops1 however1 the three-phase system is quite suitable4 ,that is to say1 it is a possible solution of the main line problem4 ,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 motor4 ,their problem was to find an arrangement which required one overhead conductor instead of three1 and also provided a motor with the high starting torque and easy speed control of the continuous-current motor4 ,after much theoretical and experimental work1 they found it in the single-phase system1 using a motor which is similar in many respects to the continuous-current motor but capable of being operated by alternating current4 ,on the advice of ,mr ,philip ,dawson1 the ,london1 ,brighton and ,south ,coast ,railway ,company decided to experiment with this system on the double line connecting ,london ,bridge and ,victoria stations1 about #i miles long4 ,power is supplied to each track by a single overhead conductor carrying current at #fjjj volts4 ,transformers are placed on the trains to bring the pressure down to #cjj volts2 the current is then led through controllers to single-phase motors in much the usual way4 ,the reason for using so high a pressure on the overhead line is not only economy in transmission4 ,if lower pressures were used1 the heavy currents required for train propulsion would require a thicker conductor and correspondingly heavier supports4 ,at #fjjj 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 tramway4 ,the power distribution arrangements1 it will be noticed1 are very much simpler than with continuous current on the third-rail system4 ,there are no sub-stations with rotary machinery4 ,power is supplied direct from the generating station to the overhead line and is transformed down by stationary plant on the train itself4 ,single-phase traction represents1 in fact1 power transmission for railway purposes reduced to its simplest elements4 ,the overhead construction differs1 however1 in some important points from the tramway standard4 ,the supports1 which are in both bridge and bracket form1 are stronger2 the insulators are1 owing to the much higher pressure employed1 more massive2 and a different means of suspension has been adopted4 ,each conductor is hung by links from two steel cables stretched chain-wise between the supports4 ,this method of 'catenary suspension' enables the bow to slide along the wire without the jolts which are noticeable with a tramway trolley4 ,such smooth running keeps the bow continuously at an even pressure on the wire--an advantage which is of great importance at high speeds4 ,the trains are arranged on the multiple-unit system4 ,the full financial results obtained on this railway have not so far been made public2 but it is sufficient for our purpose to note that the ,company1 after more than a year's full trial1 extended the system to the ,crystal ,palace and to ,croydon4 ,further extensions are1 it is understood1 contemplated over the suburban lines to ,sutton and elsewhere2 and in course of time the conversion of the main line to ,brighton will be undertaken4 ,here we touch upon the most interesting aspect of this demonstration of electric traction on the single-phase system4 ,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 traffic1 suburban and main line4 ,but the advisers of the ,company had also in view the possibility of development beyond the range of suburban traffic4 ,they therefore sought a system which1 while comparable to the third-rail continuous current in the handling of suburban business1 would be adaptable to main line conditions1 where infrequent stops and long runs at high speeds are the rule4 ,the adoption of electric traction on such a route as the ,brighton main line would be a benefit in several ways4 ,it would lead to a faster express service1 as the high overload capacity of the electric motor enables it to take small account of gradients4 ,it would also lead to a more frequent service1 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 trains4 ,further1 it would1 by reducing the time lost in stopping and starting1 bring the average speed of stopping trains much closer to that of express trains4 ,all these improvements--assisted1 probably1 by lower fares--should lead to a great increase in the volume of traffic1 thus reproducing the characteristic results of electric traction on suburban lines4 ,footnote #a3 ,an admirable explanation of alternating currents will be found in ,mr ,frank ,broadbent's ,chats on ,electricity4 7,werner ,laurie1 #aiaj47 ,,chapter ,,xv ,,curiosities ,,of ,,electric ,,traction ,like many other industries1 electric traction has had its history brightened and made picturesque by curiosities of invention4 ,locomotion has1 in fact1 been a favourite field for the freak inventor2 and some of his efforts with electric cars have been as weird and as fatuous as the most remarkable of perpetual motion devices4 ,one of these electrical monstrosities was1 indeed1 a kind of perpetual motion arrangement4 ,it was invented about the year #ahij and consisted of a car equipped with accumulators which supplied power to a motor which drove a hydraulic pump1 which in turn worked a dynamo supplying current to motors driving the axles of the car1 and also to the accumulator for re-charging purposes4 ,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 ends1 fitted with revolving fans to break down the air-pressure1 in order that a speed of #abe miles per hour might be achieved4 ,his name was ,amen2 and it provides a fitting comment upon his scheme4 ,illustration3 ,fig4 #ac4 ,illustration of ,elberfeld-,barmen hanging electric railway4 ,from ,the ,electrical ,industry 7,books on ,business71 published by ,messrs ,methuen4 ,several electric flying-machine ideas found their way on to the patent records4 ,in #ahic a ,frenchman registered a design for an air-ship with a cigar-shaped body and electrically-driven propellers4 ,there was1 however1 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 rails4 ,curiously enough1 other original inventors tried to get the opposite effect1 by devising magnetic arrangements to increase the adhesion of the wheels to the rails4 ,more plausible forms of super-ingenuity have been exercised in connection with established modes of electric traction4 ,for the conduit system one inventor suggested a kind of reversion to the 'continuous valve' of the old atmospheric railway4 ,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 along4 ,this arrangement was actually tried on an experimental track in ,london4 ,another inventor proposed a novel plan for keeping the conductor in a conduit free from damp4 ,the conductor was to be made hollow1 so that hot air could be pumped through it to dry off any accumulated moisture4 ,illustration3 ,fig4 #ad4 ,the ,heilmann electric locomotive--a generating station on wheels4 ,the general arrangement of this locomotive should be compared with that of the modern electric turbo-locomotive described on p4 #acj and illustrated in ,fig4 #ae4 ,the most entertaining freak in connection with the trolley system was a device to enable two lines of car to use a single trolley wire4 ,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 again4 ,the only drawback to this arrangement was that it would not work4 ,another inventor who was apparently impressed with the noise of trolley wheels on the wires designed a trolley head fitted with a pneumatic tyre4 ,if he could have persuaded indiarubber to be anything but one of the best of insulators1 he would have been completely successful4 ,one of the best known of electrical freaks--the ,heilmann locomotive 7,fig4 #ad7--;is a very good example of the way in which an invention may be tried with enthusiasm1 rejected with contumely1 and revived at a much later date in an improved and more promising form4 ,the ,heilmann locomotive was practically a generating station on wheels4 ,it carried a boiler and engines1 which drove a dynamo1 the current from which was led through controllers to motors coupled to the wheel axles4 ,it was an enormous affair1 over #ah metres long and running on sixteen wheels2 extensive trials were made with it on the ,western ,railway of ,france in the early nineties4 ,some advantage was gained in smoothness of running1 ease and uniformity of control1 and improved acceleration2 but its great weight1 cost1 and complexity were against it4 ,in spite of the cordial support given to it by railway engineers1 it was soon relegated to the scrap-heap4 ,illustration3 ,fig4 #ae4 ,electro-turbo-locomotive built by the ,north ,british ,locomotive ,company for experimental purposes4 ,this locomotive is a 'generating station on wheels4' ,it carries a steam turbine driving a dynamo which supplies current through a controller to motors geared to the axles4 ,the ,heilmann locomotive1 it will be noticed1 is similar in principle to the petrol-electric systems of propulsion now in use for road traction4 ,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 turbine4 ,it was natural that the locomotive engineer should consider how the turbine could be applied to his purposes2 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 axle4 ,consequently1 when the engineers of the ,north ,british ,locomotive ,company set to work in #aiji to design an 'electric turbo-locomotive1' they produced something not at all unlike the ,heilmann locomotive4 ,the equipment consists of a steam turbine1 with elaborate condensing plant1 a generator1 and a group of driving motors 7,fig4 #ae74 ,the turbine runs at #cjjj revolutions per minute and drives a continuous-current dynamo1 the current from which passes through controllers to four motors which can be run in series1 or two in series and two in parallel1 or all in parallel1 according to the draw-bar pull required4 ,trials with this locomotive were begun early in #aiaj1 but it is yet too early to say whether it will be more fortunate than the ,heilmann locomotive1 and whether it is likely to delay the advance of the electric locomotive proper1 fed with power by overhead wires from a central power station4 ,illustration3 ,fig4 #af4 ,diagrammatic sections of the ,behr electric mono-rail car4 ,the car is balanced on the summit of a continuous trestle and is designed for speeds up to #abj miles per hour4 ,the possibilities of high speed on a mono-railway1 and especially an electric mono-railway1 have acted like a will-o'-the-wisp to the imaginations of many engineers4 ,of the various systems suggested1 only one--the gyroscopic mono-railway invented by ,mr ,brennan--seems likely to survive2 and even in that case victory under practical conditions is not yet certain4 ,at ,ballybunnion there is a steam mono-railway which has been at work since #ahhh4 ,it has had1 so far as ,i am aware1 no imitators2 but its engineer1 ,mr ,behr1 retained so much faith in the principle that he decided to apply it to the problem of high-speed electric traction4 ,during the #aijj session he promoted a ,bill for the construction of a mono-railway between ,liverpool and ,manchester4 ,there was tremendous opposition from the existing railway companies1 which brought experts to prove that ,mr ,behr was a vain dreamer2 but the ,bill succeeded4 ,the promoters1 however1 found it much harder work to raise capital for the project4 ,they needed close upon #c1jjj1jjj1 but the public response to the first invitation was so small that the scheme was abandoned4 ,the line1 as projected1 was nearly #ce miles long2 and a speed of #ajj miles per hour was intended1 reducing the time of the ,liverpool-,manchester journey to twenty minutes4 ,at each end of the line 7which was a double one7 a steep gradient was arranged to facilitate starting and stopping--an arrangement1 by the way1 which is adopted to a certain extent on ,london tubes4 ,the track itself was shaped like an inverted ,v1 and practically the whole of the weight of the cars was borne upon a rail at the top4 ,the wheels1 therefore1 were right in the centre of the car1 which balanced itself on the trestle with its centre of gravity below the rail4 ,each side of the trestle carried two guide-rails which bore against free-running horizontal wheels on the car to prevent any undue lateral movement4 ,each car was designed to carry four motors with a total normal capacity of #afj horse power and an overload capacity up to #cbj horse power4 ,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 railway4 ,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 sleepers4 ,the cars are held upright by flanged wheels on the top1 running on a rail fixed to the roof of tunnels or to standards not unlike those of an overhead trolley4 ,this railway has been exhibited in the form of a model4 ,illustration3 ,fig4 #ag4 ,the ,brennan gyroscopic mono-railway4--,the car is electrically driven1 and its equilibrium is maintained by the action of two gyroscopes1 also electrically driven4 ,mr ,brennan's gyroscopic mono-railway was first shown1 in a small size1 at a conversazione of the ,royal ,society in #aijg4 ,full-sized cars were constructed later1 and one was seen at work during the ,japan-,british ,exhibition of #aiaj4 ,the distinguishing feature of the vehicle is the use of two gyroscopes 7electrically driven71 one horizontal and the other vertical1 to maintain the car upright on a single rail1 even when loaded unevenly and running at a fair speed round sharp curves4 ,from one point of view1 the gyroscopic car is no more wonderful than a spinning top1 but the spectacle of a vehicle running steadily on a single rail was so extraordinary that the interest of the whole world was immediately aroused4 ,support was given to ,mr ,brennan's experiments by the ,india ,office and the ,colonial ,office1 on the ground that a railway which required only one rail1 and was more or less independent of both curves and gradients1 would be of great value in districts where the ordinary two-track railway might be both inconvenient and too costly4 ,one drawback to the arrangement is the necessity of fitting each vehicle with gyroscopes1 which are expensive and delicate pieces of apparatus4 ,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 long4 ,the only electric mono-railway actually at work is the 'hanging railway' at ,elberfeld in ,germany 7,fig4 #ac74 ,this railway is an evolution from the system of 'telpherage' which was devised in the very infancy of electric traction for the transport of goods4 ,the root idea is to make the overhead wire carrying the current the track rail as well1 the whole contrivance--rails and cars--being suspended from girders or cables supported by a series of standards or bridges4 ,at ,elberfeld the cars pass over streets and also over canals4 ,there are no signs1 however1 that the 'hanging railway' will have any imitators4 ,in appearance and in cost of construction and operation it does not seem to have any conspicuous advantages over a double-track overhead railway4 ,the system of telpherage is therefore likely to be confined to the carriage of goods from one part of a factory to another1 and 7in the form of cable-ways7 to the handling of materials in mines and other extensive engineering works4 ,for such purposes it is having an increasingly extended application4 ,illustration3 ,fig4 #ah4 ,the ',telpher' system of electrical locomotion adapted to the transport of materials in a factory4 ,the 'car' is suspended from a girder and is operated by the driver in the same way as an electric car4 7,from ,electrics47 ,,chapter ,,xvi ,,the ,,future ,nothing irritates an electrical engineer more readily than the repetition of the phrase1 ',electricity is in its infancy4' ,the words have been used by countless mayors and aldermen while 'inaugurating' tramway or electric lighting schemes2 they have been echoed by innumerable journalists who persist in maintaining a ,jules-,verne attitude towards the electrical industry4 ,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 life4 ,nevertheless it will be admitted1 from the rapid survey which we have taken of electric traction1 that the potentialities of electricity in locomotion make an even stronger appeal than the actualities4 ,except in one field--the tramway field--engineers have only touched the fringe of possible developments in electric locomotion4 ,even in tramway work we may1 if legislative conditions improve and if current becomes much cheaper1 see a considerable development in passenger and also in agricultural lines4 ,meanwhile the trolley omnibus offers a prospect of extension in electric road traction2 and there is a great deal yet to be done with petrol-electric vehicles and with electric automobiles in certain classes of transport4 ,the great field1 however1 lies in railway traction4 ,there are #bjj miles of electric railway in the ,united ,kingdom2 and there are nearly #ac1jjj miles of steam railway4 ,not even the most sanguine electrical missionary will believe that this difference can be materially altered within the next decade1 but there is ample ground for faith in the steady increase of the electrical figure4 ,if the advance of electric traction on railways must be slow1 it is because financial and not engineering considerations govern the speed of conversion4 ,no railway company can take a step involving hundreds of thousands of pounds1 and a revolution in working methods1 without prolonged consideration and elaborate preparation4 ,on roads1 on tramways1 and on railroads1 the future lies with electricity--wholly on railroads and tramways1 perhaps not wholly on roads4 ,there is scope for it also at sea2 and if our canals are worth the cost of reconstruction on modern lines1 electric haulage will be used there on the model of the canal haulage installations which exist here and there on the ,continent4 ,for marine work the advantages of electricity have yet to be confirmed by practical experience2 but on land it has already proved that it supplies a means of locomotion which is more efficient1 cleaner and more attractive1 and more closely adapted to the needs and distribution of modern population than any other4 ,the fashion for devising ,utopias is not so popular as it used to be1 but in every ideal world which is more than a spiritual vision1 and in every intelligent forecast of an advanced civilisation1 universal electric transport is taken for granted4 ,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 profit4 ,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 #aiaj4 ,mr ,ferranti looks forward to a national scheme for the supply and distribution of electric power4 ,under this scheme1 the production of electricity would be concentrated in one hundred huge power stations1 using engines of enormous capacity and acting as wholesale suppliers of electrical energy to towns1 railways1 tramways1 and factories4 ,the price of electricity would then be a fraction of what it is now2 and all the economies of electricity in action would be multiplied accordingly4 ,technically1 the scheme is quite feasible2 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 measures4 ,,index ,acceleration1 #bc et seq4 on electric railways1 #ajg1 #aaj ,accumulators1 #gj on air ships1 #ij on ships1 #ij ,aeroplanes1 #ij ,alternating current1 #cj1 #aae ,automixte 7petrol-electric71 #he ,automobiles 7electric71 #gj et seq4 advantages of1 #hj hiring of1 #ge in ,united ,states1 #gi ,batteries 7electric71 #ac ,behr1 ,f4 ,b41 #aca ,blackpool1 #cg ,bournemouth1 #ch ,braking1 #fg ,brennan1 ,l41 #acb1 #acd ,brighton line electrification1 #aag ,broadbent1 ,f41 vii1 #aaf ,brunel1 #h1 #aa1 #ag ,cab 7electric71 #gh ,city and ,south ,london ,railway1 #ig ,conduit system1 #bh1 #cg1 #abf ,continuous current1 #aaf ,district ,railway1 #ajc1 #aai ,durtnall1 ,w4 ,p41 #hh ,dynamo1 #ac reversibility of1 #ae1 #fg ,elberfeld-,barmen ,railway1 #abe1 #ace ,electric traction advantages of1 #ai et seq4 automobiles1 #gj et seq4 backwardness of1 #df et seq4 on main line railways1 #aaf1 #abb ,faraday1 #ac ,ferranti1 #adj ,fischer 7petrol-electric71 #he ,giant's ,causeway1 #ic ,griffiths-,bedell 7,g-,b47 system1 #dd ,gyroscopic railways1 #acb ,hanging railway1 #abe1 #ace ,heilmann locomotive1 #abh ,kearney1 ,e4 ,w4 ,c41 #acc ,launches 7electric71 #gc ,light ,railways ,act1 #eh ,liverpool ,overhead ,railway1 #ig1 #aaa ,locomotive 7electric71 #ab1 #ig1 #ajh ,heilmann1 #abh turbo-electric1 #abi ,london electric cabs in1 #gi electric railways in1 #ig1 #ajc tramways in1 #ci1 #ec ,lorain system1 #dd ,lyttelton1 ,a41 #aai ,marylebone1 #ha ,mavor1 ,h41 #hh ,mersey railway1 #ig ,mono-railways1 #aca et seq4 gyroscopic1 #acb ,motor 7electric71 #ad ,multiple-unit system1 #ii1 #ajh ,omnibus 7electric71 #gg petrol-electric1 #hc ,overhead system1 #ag1 #abh ',paragon' system 7ship propulsion71 #hg ,petrol-electric system1 #hb et seq4 ,provisional ,orders 7,tramways71 #dh ,railless traction 7see trolley omnibus7 ,railways atmospheric1 #g cheap power for1 #aac experimental electric1 #af finance of1 #ajj opposition to1 #f pioneer electric1 #ib1 #if rope1 #g ,raworth1 ,j4 ,s41 #fh ,regenerative control1 #fg ,series-parallel system1 #cb1 #aae ,ship propulsion1 #hh ,siemens1 vii1 #ad1 #af1 #aad ,signalling 7automatic71 #aab ,single-phase system1 #abj ,starting torque1 #bc 7see also acceleration7 ,stephenson1 vii1 #e1 #i ,storage batteries1 #gj et seq4 ',stud' system1 #db ,telpher system1 #acf ,third rail1 #af ,three-phase system1 #aah ,torquay1 #dd ,trackless trolley 7see trolley omnibus7 ,trailers1 #bf ,tramcars equipment of1 #ca ,tramroads early1 #d ,tramways accumulators on1 #bj conduit1 #bh1 #cg1 #abf cost of1 #ec generating equipment for1 #bb inter-urban1 #ej legislation for1 #dg municipal1 #di overhead system on1 #ag1 #abh statistics1 #bg1 #bh surface-contact1 #bh1 #db ,tramways ,act 7#ahgj71 #ie ,trolley omnibus1 #ef1 #fj et seq4 in relation to tramways1 #fe ,trolley system #ag1 #bi et seq4 bow1 #ca ,tube railways1 #ig ,turbo-electric locomotive1 #abi ,veto 7tramway71 #dg1 #ea ,waterfalls electric power from1 #id ,watt1 vii ,wheatstone1 #ad ,wolverhampton1 #dd ,workmen's fares1 #ec ,yerkes1 ,c4 ,t41 #ajd ,cambridge3 ,,printed ,,by ,,john ,,clay1 ,m4,a4 ,,at ,,the ,,university ,,press ,transcriber's ,note3 ,italics are indicated by underscores4 ,bolds are indicated by equal signs4 ,small capitals have been rendered in full capitals4 ,footnote is placed to the end of chapter4 ,a number of minor spelling errors have been corrected without note4