By William Newby Colam, M. Inst. C.E., M. Inst. M.E.

This paper, from The Proceedings of the Incorporated Association of Municipal and County Engineers, Volume XIV, 1897-98, was written by William Newby Colam, an engineer who participated in the construction of several UK cable tram lines. In this paper, he discusses developments on the Edinburgh's cable tramways, which he designed and built. He presented the paper on 30-June-1898. He gives updates on the evolution of the system since his 1890 paper, Edinburgh Northern Cable Tramways.

From Proceedings, Incorporated Association of Municipal and County Engineers, Volume XIV. -- 1897-98. (London, England).


By WILLIAM NEWBY COLAM, Vice-Pres. Soc. Engineers,
Assoc. M. Inst. C.E., M.I.M.E., &c.

The Author regrets that the time given for the preparation of his paper has not been sufficient to enable him to deal with the subject in a more technical manner, but he hopes the practical results of working given will be of some use to the Members.

On the occasion of your Association's last visit to this city in the year 1890, the Author had the pleasure of submitting a paper explanatory of the construction and working of the Edinburgh Northern Cable Tramways, and on this occasion the Author trusts it may be considered opportune to lay before the Members the last eight years' experience in operating these lines, and to describe the conversion from horse to cable traction at present in hand within the Edinburgh boundaries, and also as about to be proceeded with in the Leith domain.

In 1890 the cable system in Edinburgh was in its infancy, as the second line built had only been opened to the public in the month of February of that year, and the first line in January 1888. The information available at that time as to the operating costs was not reliable, because the lines had not been at work long enough to ascertain how far the working costs would be increased after the lines and machinery had been in use for some years. This can now be given without any dubiety from the regular balance sheets for the last ten and a half years up to the date when the Corporation of Edinburgh bought up the lines at a price which yielded a profit over the original cost of construction of about 30 per cent.

The conditions under which these lines have been compelled to operate cannot be considered conducive to the best financial results for either receipts or expenditure, for the following amongst other reasons :--
1. The maximum speed was limited to six miles per hour when the system was inaugurated, mainly because it was something new, and has not since been raised because in the hilly district perhaps slow speed is not so noticeable.
2. No Sunday traffic on tramways has been permitted.
3. The routes are most exceptionally hilly.
4. The ends of the routes are not built over, and lead nowhere in particular.
5. The engines are high-pressure non-condensing, working at low pressure of steam.
6. There are no economiser means of utilising the gases; nor feed water heaters.
7. The whole managerial department was in London, which necessitated heavy travelling expenses.

Notwithstanding the unfair limitation in speed and other drawbacks, the results have been eminently satisfactory, as will be seen from the following statement (Table No. 1) made from a comparison of results in 1890 with the last year of the company's working in 1896.

Table 1

The tabulated results of No. 1 must be somewhat puzzling to the uninitiated in cable haulage, because, when analysed, they show that although the mileage has been increased 69.06 per cent., and the number of passengers carried increased 43.88 per cent., the cost of motive power, instead of being greater, happened to be less.

The reduction in cost of motive power has been due to improvements and a slight reduction in the price of coal, and the reason for no increase is that the loads up and down balanced on an average. These figures once more prove that cable haulage is able to enormously increase its car service and so provide for the future without appreciable increase in its working expenses.

It will be observed from the returns of working that, whereas the number of passengers only increased 43.88 per cent., the car mileage increased 69.06 per cent. This is most important to note, because it points to a factor peculiar to cable haulage. It is directly in the interests of the management to improve the service of cars beyond even the requirements of the public, because, beyond the wages of the drivers and conductors, very little extra is incurred in placing each additional car on the line.

Even more satisfactory results than are shown in Table No. 1 were recorded on one of the cable lines during a week of greatly augmented traffic, and the Author now presents these figures, believing them to show the most unique results for the conditions of operating which have ever been obtained in tramway practice in Great Britain. The ordinary weekly working expenses given in the Table were arrived at by a division of the yearly certified accounts of fifty-two weeks, and the increased cost of operating was carefully cheeked during the week, and was mostly due to wages and gratuities given to the men and inspectors for close attention to their duties.

Table 2 shows that with the same fares a cable tramway was able to increase its receipts 311 per cent. by a rise of working expenses of 12 per cent. only.

That by quickening the service of cars by 1 1/4 minute, when the traffic would warrant it, the working expenses per car mile run were reduced 3/4d.

That the tons hauled per mile increased 24 per cent., and the cost of hauling a ton mile was reduced 33 per cent. This is elasticity in the right direction, and the Author is of opinion that Local Authorities and Tramway Companies too often make the mistake of not thoroughly arriving at sound conclusions as to the elasticity of a mode of traction in this direction when considering the initial cost of systems under scrutiny.

Table 2

The last return of the company's workings showed that the cost per car mile, including every charge possible, excepting depreciation and interest on capital, was 5.2 pence, notwithstanding the restriction on speed and the severe hills, &c. The receipts per car mile had only been 10.13 pence, which was just about what the cost per car mile run has been on the horse system of Edinburgh. The foregoing facts conclusively prove that the lines have been a great success financially, and the fact of the Corporation of Edinburgh still favouring cable should be sufficient authority for the statement that mechanically they have met with public approval.

Having now brought the paper read before you in 1890 up to date, the Author will lay before the Members some particulars as to the big system of cable haulage which the Corporation of Edinburgh are nearing the completion of.

The Corporation of Edinburgh has purchased all the tramways within the limits of the borough, and they have leased the working to a company for 21 years, the company agreeing as follows --
1. To pay interest of 7 per cent. upon the price paid by the Corporation for old lines, and the same rate of interest upon all sums of money expended by the Corporation in converting to any form of mechanical traction they choose.
2. To pay the cost of maintaining the tramway tracks and other works.
3. To reduce the hours of workmen as desired by the Corporation.
4. To pay 3 per cent. upon sums expended by the Corporation in reconstruction until the lines are finished.

The Corporation, by borrowing the necessary money for the purchase and construction of lines at 2 1/2 per cent., and by getting 7 per cent, from the lessees, will be able to write off the cost of the tramway system within the terms of the lease.

The Author thinks that the Corporation is to be congratulated upon the arrangement made, and suggests that those who advocate municipal working of tramways might consider the Edinburgh arrangement worthy of favourable reflection.

Before entering upon descriptive matter, it may be of primary interest to give what the Author believes to have been some of the Corporation's reasons for adopting cable haulage in preference to other mechanical powers which have found favour elsewhere.

First of all, it must be stated that the original lines were self-contained, and were in no measure the inducement for extending the system for the preservation of continuity.

Secondly. The overhead wire system of electricity, which was the only other system reported as being anything like a financial success, was not entertained in Edinburgh because of its interference with the amenities of the city.

Thirdly. Because the contour of the city is peculiar in being exceptionally hilly, and where so many hills exist in a city, it is of paramount importance that the speed ascending hills shall not be less than that attainable on level portions of the routes.

Fourthly. The buildings limit line of the city is more markedly defined than in most cities.

Fifthly. The cable system in Birmingham, London and Edinburgh had placed the fact beyond a doubt that the Corporation could treat for a lessee with full knowledge of what would be an approximate working cost per car mile with the cable system, whereas by any other system which could be in any way considered, no such reliable information was available, particularly from experience of operating under British Board of Trade Regulations. Further, it is within the Author's knowledge that eminent electrical opinion has been given that Edinburgh is not a suitable place for electric traction in any form.

The following table gives the miles of lines within these respective districts reduced to single track of tramway.

Table 3

No. 1 is one of the new depots from which all the cables in the south-west and westerly districts are to be operated, and provision is here made for extensions in these districts.

No. 2 depot is being constructed on a portion of the stable land of the horse tramways, and from here the whole Leith and south-east cables will be operated.

No. 3 depot is to be a small depot principally for the storage of cars for the eastern district, but an engine is to be placed here to work the Portobello and Waterloo Place lines, at higher speeds than would be convenient through the centre of Edinburgh.

The old cable depot at Henderson Row will not be done away with, as it will be useful for extensions of the system on the northern districts.

Throughout the system there will exist nearly all conditions of tramway operating which are to be met with in ordinary practice. For instance, the grades are as high as 1 in 11, there are right-angle branches, "S" junctions and compound triangular junctions to be worked. Single lines of track with passing places are not common, but at places are required. Cross traffic, where cables cross each other, have also to be dealt with. Bridges and cellars have already been crossed by the cable construction in Edinburgh, when clearances of 14 inches only from the surfaces of the roads have been available, and lastly, an arrangement for crossing a swing bridge in the Leith district has been designed.

Arrangements are made by which the traffic can be returned (or short circuited) through turn outs when the management considers it will be advisable during parts of the day to provide an augmented service of cars short of the terminus of the route, and such provision is also made for isolating a cable section where a block may occur.

The general speed of cars throughout the Edinburgh district is to be eight miles per hour, but passing round important corners and over congested crossings, the drivers of care will not be able to acquire a higher speed than four miles per hour, and they will be able to go as much slower than four miles as may be required.

Provision is being made to increase the maximum speeds when the Board of Trade may give permission. In the outlying district of Portobello, it is expected that the Board of Trade will raise no objection to nine miles.

The permanent way will perhaps interest the Members as much as anything on the cable tramways at their present stage of construction. The track rails are of the usual type now common for tramways, and are 6 1/2 inches deep, weighing 83 lbs. to the yard run. The joint adopted by the Corporation of Edinburgh was quite new, as will be seen from the specimen produced. The two objects sought to be obtained are --

Firstly. That the wheel in rolling along the tread of the rail shall not, in passing from one rail to the other, be left without a support, and thereby it is hoped that all chances of concussion due to break-joint will be abolished.

Secondly. That by the arrangement of recessed nuts and flat cheese-headed bolts, the paving may be brought square up to the edges of the rails, and the Author submits these two improvements are of very considerable importance.

The tests of 42 to 44 tons per square inch for tensile, 15 to 20 per cent, on 8 inches for elongation, and 40 to 45 per cent, contraction, called for in the specification, were objected to by British manufacturers, but the engineers are pleased to report that the effort was made and the tests were fully obtained, with the result that extremely hard and yet tough rails have been laid in the system.

The slot rail, a specimen of which is also shown, weighs 48 lbs. per yard, and are made of a somewhat milder steel than the track rails, the tensile asked for being 39 tons to the square inch, with 15 per cent, elongation and a contraction of 30 per cent. The actual amount of metal appearing on the surface of the street in these slot rails is 1 3/16 inch. Against these rails also it will be observed that the paving setts can be placed right up to the edge of the rail without any chipping, and on a square bed, which is important. The Barrow Haematite Steel Company carried out one contract for rails, and Messrs. Dick, Kerr and Company, Limited, the other.

The points and crossings are all to be made of steel, and no facing points are used excepting where they cannot be avoided, such as at junctions.

Trailing points for track and slot rails will work by springs, but where facing points are required, the track poiuts are connected underground to the slot points by levers in such a manner that, whichever way they are thrown over, there is a locking apparatus introduced to fix the slot correctly with the track points.

The slot points are built up of cast and spring steel.

The track points are made of cast steel, and track over slot and slot over track crossings are built up from the section of these rails, but the junctions of slot and slot are made of cast steel with renewable points.

The paving setts are granite, of two qualities as far as workmanship is concerned. Specimens of these two qualities are exhibited. Inside the track the setts are 3 inches wide by 5 inches deep, and the average length is about 6 inches. Outside the track the setts are 6 inches deep by 3 inches wide. The better quality of setts are axed on top as well as square on ends and sides. The hatch covers, which are used in the track for obtaining access to the pulleys, are filled with granite setts specially dressed, and of the same size as other setts, so that in ordinary conditions they are almost imperceptible on the road surface.

In the road construction a great deal of wood has been used, and this has chiefly been of the hard Australian qualities.

In some cases the wood has been laid from curb to curb, including inside the tramway track.

The standard distance between the tramway tracks is 4 feet, but where the streets are narrow this has been reduced to 3 feet. At places where the streets are exceptionally wide, the tracks have been spread apart to give a distance between of 6 feet, and electric light posts have been erected in the centre.

The width of the slot is specified to be in no case more than 3/4 of an inch.

The terminal pits for diverting the cables at the terminal of each route are not of the design described in the Author's paper of 1890, but are so constructed that, regardless of whether the route ends on an incline upwards or downwards, the cars will proceed to the extreme end of the journey by means of the cable, and no gravitation whatever will be resorted to. This is attained by passing the cable around two large vertically placed pulleys, one behind the other, and one slightly inclined. By this means, even in a heavy snowstorm, a car could proceed through the snow to its terminus, and start out again without the tracks being cleared.

Where cables terminate in the middle of a route and meet other cables, the two cables are made to lap past each other by arrangement of large pulleys placed in a pit.

At these places the cables are so arranged that the operation of releasing from one cable and taking the other is performed while the car is at a state of rest, and will not require more than 15 seconds to accomplish the change over. The operation is practically automatic.

The reduced maximum speeds of cables for passing round important main corners in streets is obtained by the introduction of auxiliary cables, which are worked off the axles of large pulleys kept in motion by the main cable, and the main cables are thus saved from a great deal of hard work, and their lives, consequently, will be materially lengthened.

The Author feels sure that the following information as to the rate at which cable tramways have been laid in Edinburgh will be of interest to the Members.

There seems to be an idea existing that cable tramway tracks are very serious innovations for streets, because they require a tube construction besides an ordinary tramway track.

The following information will confute any such erroneous impression.

During the first twelve months of the contract, there were laid in the streets of Edinburgh a trifle over 20 miles of cable track.

The greatest speed attained was during six consecutive days, when an average of 220 yards per day was attained on one section of new lines.

It will be seen that the amount of finished work during twelve months averages out to a little more than 112 yards per working day, which would be considered splendid work for an ordinary horse tramway line, where the traffic is such as in Edinburgh, and where the tramway service has to be maintained.

The contract for road and pit work was secured by Messrs. Dick, Kerr and Company, Limited.

The depot for the Western District is the most important, and as some of the Members may be visiting it, the Author will briefly describe the construction and equipment which is intended for this depot.

The site is by no means an ideal one for the purpose, but by its adoption a miserable collection of houses has been removed, and a great public improvement has been effected. The buildings stand one block and a street back from the main road, and the communication between it and the main tramway is through a very narrow lane.

The principal materials used in the building are red stone and a fine quality of brick, the former being exclusively employed for the front elevations. The buildings include engine room, boiler room, chimney 180 feet high, pump room, built-in water tanks to hold 40,000 gallons, tension room, car sheds for 43 cars, cart sheds and stable for three horses, store for road work and underground stores for oils, &c, lavatories, offices, &c.

The chief station for storing, painting and repairing cars is at No. 2 station, where the sheds are divided into sections to isolate the cars in case of fire. Total accommodation for the storing of 225 cars is being provided.

The engines are horizontal compound, non-condensing, with cylinders placed side by side on separate cranks set at right angles. There are three pairs of engines attached to the one line of main shafting.

Each main shaft is divided into sections which can be connected by specially arranged couplings forged on the shaft ends. Two 14 feet 6 inches diameter grooved pulleys are mounted in the line of shafting, so that any two of the three engines can be geared to work the two pulleys. These pulleys are made for carrying 32 ropes of 1 5/8 inch diameter, and they will revolve at 45 revolutions per minute. The power of the engines will be transmitted to the counter-shaft through pulleys 30 feet diameter.

The high-pressure cylinders are 23 inches, the low-pressure cylinders are 40 inches diameter. The stroke is 5 feet.

A premium of 5l. per cent. was offered as a bonus on the contract price of the engines for every pound of water per indicated horse-power consumed per hour less than the 20 lbs. specified.

In like manner a deduction of 5l. per cent. will be made, but should the consumption per indicated horse-power reach 23 lbs., the engines may be rejected.

The engine room is provided with two cranes to lift 24 tons each.

Messrs. Dick, Kerr and Company, Limited, secured the contract for this portion of the work.

The Boiler House. This is placed immediately behind and considerably lower than the engine room.

The coals taken in off the road have not far to be lifted into the bunkers over the boilers. All the pipes to and from the boilers and engines pass underneath the engine room floors without dipping, and do not appear at all in the engine room, also the low level of boilers should also reduce the chance of priming through syphoning.

The boilers are cylindrical marine type, 10 feet 6 inches by 12 feet, with super-heater tubes on the top. The gases from the fire enter a back combustion chamber, from which they pass to the front of the boiler through tubes into the smoke box. They are returned over the top of the boiler, passing on their way around super-heater tubes into a second back chamber which directs the gases along the bottom of the boilers into the main flue.

Apparatus is provided for diverting the gases down the sides of the boilers, in case the super-heater tube should require attention when the boiler is under steam. The duty of these boilers is to evaporate not less than 9000 lbs. of water per hour at a boiler pressure of 160 lbs. There are four such boilers, designed to work up to a pressure ultimately of 160 lbs. These boilers will not be worked to anything like their full capacity, and a large reserve will always be kept in hand.

The main steam piping is welded steel, and all in duplicate. The feed pipes are in copper and are duplicated. The boilers are fitted with "Vicar's Mechanical Stokers," supplied with coal from an overhead bunker running the full length of the boiler house. Coal is taken up with ropes to the bunkers in receptacles resembling contractors' steel waggons, which are so adapted that they are suitable either for use on the body of a cart through the streets or to form the tipping body of a tramway coal truck which will travel on rails over the top of the coal bunker.

There are two heaters, arranged so that they may be used together or separately. These are of the "Brown Berryman type," and each heater is capable of passing 1600 gallons of water per hour. The pumps are in duplicate, and are 8-inch double vertical "Weirs type."

The arrangement of pipes from the pumps is to effect the following

Combination Of Feeding.

(a) All the boilers may be fed with hot water.
(b) All the boilers may be fed with cold water.
(c) Any number of boilers may be fed with hot or cold water.
(d) Any one boiler may be fed with hot and cold water.
(e) Any one boiler may be fed with hot or cold water.

Messrs. George Sinclair are the contractors for the work in connection with the boilers, &c.

At No. 2 depot the arrangement of boilers and machinery is much the same as at No. 1, only the boiler house is not placed exactly in the same relative position to the engine house, but has the advantage of being at the side of a railway, so that a siding has been made by which means coals can be lifted direct up into the bunkers instead of having to be brought in carts as at No. 1 depot. At this depot all the smithy, repair, general machine, carpenter's, and paint shops are placed.

At both depots the cars are brought in and taken out from the main road by auxiliary cables, and they are traversed into the repair shops or ordinary sidings by traversers, also worked by auxiliary cables.

The tension races are immediately at the back of the engine rooms, and under car shed floors. This apparatus is similar in some respects to that described by the Author in 1890, excepting that the pulleys on the main carriages are placed horizontally instead of vertically, and all the tension weights are arranged vertically upon the wall of the engine room, so that the man in charge can observe at any moment the fluctuation of strains taking place upon any one line being driven from each station. From No. 1 station there will be five cables driven, and the longest at present will be 24,000 feet, but these will all be capable of considerable extension. The longest cable in the system at present is 34,500 feet. The mode of driving the cables is somewhat as explained in the Author's paper of 1890, but the grip pulley has the improved white metal jaw which has given great satisfaction in the London Cable Tramways. Each grip pulley can be thrown out of action without interfering with any other, by means of a coil clutch of powerful construction.

Opposite each rope drive there will be an iron drum, with a spare cable for its respective route, ready at any moment to be run into the road. At the side of the engine room an engine and drum is provided for hauling out old cables, and it is estimated that the longest cable will be taken out, and a new one put in, within the space of one hour.

The gripper apparatus to be placed on the cars is an important feature of the arrangements made for cabling the Edinburgh extensions. The gripper shown in the Author's paper of 1890 would not meet all the requirements of the new lines where some cables have to be taken in the gripper to the left, and others to the right, of the direction in which the car is proceeding. The new gripper also has to be able to pass over crossing cables. It has been designed and tested on the lines of the existing cables, and can be seen by the Members at the company's depot at Henderson How. The whole machinery is enclosed in a cast-iron box standing on the platform of the car, and occupying about the same space as is taken up on the car by an electric tramway standard. The main improvements over the gripper of 1890 consists of provision by which the driver of the car, standing in the front of the car, can operate the gripper by his side or the one at the rear end of the car by a simple reversing of a lever. It is by this means that the driver can cross over the cable running at right angles to his path. He proceeds to a stopping point with the gripper attached to his main cable, he then by the one process lets go that cable in the front, and takes it in the rear gripper, and proceeds over the crossing of the cable. The operation takes only a few seconds, and should be quite safe, because there is an automatic arrangement provided for stopping the car in the event of the driver being forgetful or careless. Another improvement is, that the portion of the gripper which works in the tube underground can be quickly detached from the car and dropped into the tube if anything should go wrong with it. The attachment previously used direct on to the axles of the car, was found in practice to have several drawbacks, and the new gripper is fixed to adjustable bars on the bogies, and the moving parts are enclosed so that there will be no fear of oil, &c, injuring wearing apparel.

There are 125 cars being built on the bogie principle. The bogies are very light in construction, being made of 5/16 of an inch pressed steel frames. The chief feature about them is that the wheels are on the axles outside the bearings, and that the wheel base is 3 feet 9 inches. This is contrary to customary practice, but the Author has tried them very severely, and finds them to answer admirably. The cars are designed to seat 18 passengers inside and 28 outside, and the only noticeable departure from ordinary practice is that the insides of the cars will be domed after the manner of railway carriages, instead of the type of roof common in tramway cars.

In concluding, the Author would specially invite the Members, as advisers to their respective districts, to always insist upon arriving as far as possible at --

Firstly. The saving which can be effected by any particular system over the whole period in which that system is intended to operate, before allowing the initial cost to have any influence upon the minds of their committees.

Secondly. To compare (at least in a common-sense way) with existing systems the cost of repairs which are likely to result upon each individual system.

With regard to the first point, it is not generally recognised what amount of expenditure is justified in converting horse tramways to mechanical traction.

What expenditure is warrantable upon introducing a system which can even only show a saving over the old system of 1d. per car mile run.

We will take as an illustration a town system in which it is desired to have a good service of cars, such as 1000 car miles per mile of double track per day, and experience shows this is to be quickly attained with cable haulage, which fosters, and can afford to foster, a tramway business in a way which no other system can.

One thousand car miles per mile of double track per day, with a mean car speed of 6 miles per hour (which is, of course, low), would require for working a day of 17 hours, an average interval between the cars of say two minutes, 10 cars thus running on the mile of street length, and performing 60 car miles per hour.

This would give 365,000 car miles per mile of double track per annum, and 1d. per car mile saved would be in round figures 1500l. per mile of street per annum. That sum is sufficient to pay 5 per cent, interest on a capital of 30,000l. per mile of street, and yet it is only 1d. saved per car mile.

Cable-haulage for such a service would be about 1d., and would probably be nearer 5d., per car mile cheaper than the present expenses for horse traction.

And yet there are people who still hesitate, and some even refuse, to consider mechanical forms of traction where the initial cost is high, and therefore never discover the extraordinary results and savings which may he effected in the future by the expenditure of additional capital at the right time.

With regard to the second point, the Author would like to draw your attention to the class of figures which you have to guard against.

In a paper lately read before the Institution of Civil Engineers, the costs of maintenance and repairs on an electric tramway line were given to four places of decimals as follows.

For the maintenance and repairs of cars, with motors and everything complete, .26725d. per car mile run.

The Author ventures to say that nobody will dispute that the cost of maintenance and repairs for heavy cars, with heavy motors and electrical machinery, must in the future cost far more to maintain than the ordinary horse car, and yet it can be most conclusively shown that the average cost of maintaining a horse car only in Edinburgh during 11 years has been .51d. per car mile run, or twice the figure which is quoted for electrical maintenance.

Again, it was also stated that the cost of maintenance and repairs for lines, which would include the whole of the permanent way, rails, bonding, electric poles and wires, etc., was .0088d. per car mile run. Experience shows that the average expense of maintaining the horse tracks alone in Edinburgh has been during 11 years .64d. per car mile run, or nearly seventy-three times the amounts given for maintaining electrical road and wires, etc., etc.

The Author does not wish to infer that these figures are put forward to wilfully mislead, but he cannot too strongly warn those who are seeking for information, that a few such items in the cost of maintenance would make the difference between financial success and failure. The cost of maintenance can only be properly arrived at when the fullest data of working is available over an extended period of time.

The whole of the work is from the designs of the Author and your Vice-President, Mr. Cooper, who are superintending the carrying out of the work with the assistance of their respective staffs.


Mr. F. Baker: I should like to mention to the meeting that at Middlesbrough a private company is just putting in tramways extending about ten miles, on this electric trolly system. It may interest some of you who are seeking for information in this respect to come down to see the system, and I am sure I shall only be too pleased to give any Members any assistance and information in my possession. If there are any gentlemen who would like to come down, we shall be very pleased to show them the electric trolly system.

Mr. A. E. Collins : I should like to ask the Author whether he has had any experience with the cast weld joint, and whether his experience of it is favourable. I should also like to ask as to cables, whether he has formed an opinion as to the relative values of the ordinary cable lay as compared with Laing's lay.

Mr. Paton : I beg to propose a vote of thanks to the Author. The local circumstances must determine the authority as to the character and kind of tramway which would pay them best. I can quite conceive that with wide streets and a modern town a cable tramway could be laid at moderate cost; but in old towns with narrow streets, where there is uncertainty as to the depth of drains, water and gas mains, &e., it is almost impossible to tell what will be the cost of installing a cable tramway. Personally I regard the cable as the most perfect form of tramway haulage. It does not disfigure the streets, and with a little extra power at the central station almost any number of cars can be put on, while the proportion of expense in relation to income is not the constant figure it is with horse traction. In fact, the greater the number of cars the smaller in proportion is the cost of working. In Edinburgh it is put at 5d. per car mile. That, compared with horse traction, shows a considerable saving in working expenses. But it may so happen that in a town where they determined to lay down a cable tramway the initial cost would be such that they would never get a company to pay them 7 per cent. on the capital outlay. The returns would not pay them to do so. That is a consideration, and materially affects the question of the term of repayment which would be allowed for the construction of the lines. If the Board of Trade would only allow a term of twenty-one years, it becomes a serious question what will be the state of the lines on the expiration of the lease. In Plymouth the old system was horse traction, and the company made so bad a job of it that the Corporation ultimately took it over. We are working it by horse traction, and a portion of it is being laid for electric traction. We considered at the time the cable, accumulator and overhead trolly, and after consideration the committee came to the conclusion that the overhead system was the best and cheapest for the town of Plymouth.

Mr. O. Jones : I rise to second the vote of thanks. The paper specially interested me, because we have been fighting a company for six days in Committee of the House of Commons, and I am pleased to say we defeated them. During the inquiry in Committee, some interesting points were raised by Dr. Siemens and Professor Hopkinson in connection with the conduit and the overhead system of electric traction; if anything could have been said as to the merits or otherwise of those systems, it would have been of interest to some of us, and perhaps enabled us to reply to some questions which are sometimes asked us at our Council meetings.

Mr. J. Lemon : Will the Author of the paper kindly give the cost per mile of the conversion of the system from the horse tramway to the cable tramway. The capital charge, including everything. I do not think it is in the paper; if it is, I have overlooked it.

Bailie Mackenzie (Edinburgh): We have had this matter of mechanical traction before the Council for a considerable time. We did not enter upon the cable system hastily. We looked round and found a number of companies were very anxious to put their resources at our disposal for various systems of electric traction. About two or three years ago we had several companies who were prepared to give every guarantee that within six months they would have a perfect system of underground electric traction installed. But we found there was no system of underground electric traction worth looking at. It is a very curious thing that while in America they are throwing out the overhead electric trolly system, in English cities, in Liverpool, Glasgow, Leeds, they are now going in for that system. Is it the case or is it not, that the Mayor of Chicago has made an agreement with the different tramway companies in that city, that within a certain radius of the centre of the city there is to be no overhead trolly ? Is it the case that in Washington, Boston and New York they are throwing out the overhead trolly ? It is very curious, and my own explanation is that many large syndicates with any amount of money behind them have made a raid upon the municipalities for erecting electric installations. We made particular inquiry, and on the advice of our expert, as well as from our own knowledge of what has taken place elsewhere, and the uncertainty of many of the electric systems, we decided that we would go in for cable traction. We have seen no reason to regret that decision. We have no doubt that the overhead electric trolly is a fairly good system, but we have yet to know that in such a city as ours, where frequent stoppages must take place, and where the speed cannot by the Board of Trade regulations exceed 8 miles an hour, the overhead trolly system would be as successful as the cable system has been.

Mr. J. Lorley : There are one or two things I should like to refer to in the paper. The first is the phrase "car miles." This is rather misleading, because there are cars of very different sizes. Here in Princes Street I have seen single and doubledecked cars, and in Boston I have seen cars running which will take three times as many passengers as some of the Edinburgh cars. Therefore the cost per car mile is apt to be misleading unless the number of passengers is taken into account. With respect to New York throwing out the overhead wire, I believe New York never would have that system. I saw them laying the cable system along Broadway when I was in New York; and there is also the underground conduit system in operation. They have so great a dislike to the large number of overhead telegraph and telephone wires, that they would not consent to have the number increased for tramways. In this they are quite consistent, like Birmingham has beon. The overhead trolly system has, I think, many advantages. In my own town we are now in the throes of a reconstruction, having over 2 miles of streets up for converting to electric traction and extension. I do not think after twelve months' experience that any one takes the slightest notice of the poles and wires in the streets. Notwithstanding the advantages of the overhead trolly in cheapness and efficiency, I should prefer the cable system if I could possibly have it. The roads are very crooked, and we have a large number of canal bridges, the crowns of which are not more than 12 inches above the soffits of girders, and which require to be constantly raised, owing to undermining. I have not heard that in Boston they have done away with the trolly system; when I was there I saw miles of it at work. In Washington I saw the cable system as well as the trolly, but after all they have been so overdone in America with overhead wires for all manner of purposes that I am not surprised to hear they are desirous of seeing no more of them for tramways.

Mr. Colam, in reply, said : I will take the questions asked seriatim. The first point was whether I had any experience of cast weld joints. My objections to the joint are twofold. The joint is of course designed on the assumption that no expansion takes place in tramway rails ; I think this is a mistaken notion, especially on curves. My second objection is that you cannot bring two portions of a rail together by a weld, or castweld, without changing the nature of the metal all round where the joint takes place, with a result that unequal wear must take place, and in course of time a hollow place is produced on the rail which must cause a knock on the wheels. It was introduced to make stronger rail joints, made necessary when very high speeds by heavy motors for electric traction became common in America. I use nothing else but the "Laing" lay in the construction of cables, because experience has shown it to be the best for cable haulage. Mr. Paton made some very pertinent remarks, and I thoroughly agree with him, that every district requires to be considered upon its merits. I consider the proper people to discuss the requirements of each district are not engineers but local authorities. The Edinburgh people said what they would not have, and then began to inquire what they could get. I know many districts in this country which could not, in my opinion, give better results financially than with one-horse cars if properly managed. Mr. Lobley makes a remark as to the term "car miles" being misleading. That is one of the disadvantages of not having an opportunity to read the paper. You will see that I give "ton miles " as well as " car miles." Having lived myself in a district where the overhead wire existed, I admit you can get used to it to a certain extent, and the same argument applies to almost everything. The difficulty is if you have to live in a district where four or more roads meet, and cars have to turn to the left and right as well as cross in all directions. In such cases there are so many guard wires, stays and supports necessary that the place becomes a perfect eyesore and source of danger. I should like to direct your attention to the diagram of the Edinburgh tramways, which shows our 47 1/2 miles of lines being cabled, and to ask you what would be the effect of overhead wires through such a district, more particularly in Princes Street and the complicated junctions with it. Then Mr. Lobley refers to the bridge difficulty, and to the fact that he has bridges the crowns of which have only 12 inches cover. We have four cases of that kind in Edinburgh, and they have been satisfactorily got over. Over two of the bridges we have been working by cable haulage for ten years. Bailie Mackenzie put the case against the overhead trolly system, for Edinburgh at least, in a nutshell. It would be a little derogatory for such a city as Edinburgh to take a back seat to Chicago, New York and Washington, which are well known to seldom consider the amenities of their cities and yet refuse to admit the trolly. This, as I say, is not an engineering question, but for town councils to decide. In America, where they are allowing the overhead wire to go up, local authorities are guarding themselves with a clause to the effect that when they shall be satisfied that they can find a conduit system which is economical, they shall have the power to order the wires down and reconstruction to a conduit system. Mr. Lobley is right in saying that New York would not tolerate the overhead wire. In Boston, the only city in America where narrow streets and congested traffic exists as it does in our country, the overhead trolly system has been put up, and in my opinion it has been a financial failure. Every car costs about 1/2d. per mile run, and it must be remembered that the car mile receipt which is likely to rule in this country is not likely to be more than l0d. to l1d. The necessary speed for electric traction in Boston has not been possible, and it has been found necessary to divert the car traffic underground, which of course converts the tramway system in the city to a railway.

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