The Mersey Tunnel was lately opened by the Prince of Wales, and, as the LondonStandardsays, after an infancy of troubles and failures, and a ten years' middle age of inaction, the Mersey Tunnel emerges into notoriety under the hands of Mr. James Brunlees and Mr. C.D. Fox, and of Mr. Waddell, the contractor, as a triumph of engineering skill. The tunnel is 1,250 yards in length. It is driven through solid, but porous, red sandstone, through which the water has percolated in volumes during construction, at a level of about 30 feet below the bed of the river. It is lined throughout with blue bricks, the brickwork of the invert being 3 feet in thickness. Its transverse section is a depressed oval 26 feet in width and 21 feet in height, and it contains two lines of railway. At a depth of about 18 feet below the main tunnel there is a continuous drainage culvert 7 feet in diameter, entered at intervals by staple shafts. There are two capacious underground terminal stations 400 feet long, 50 feet broad, and 38 feet high, and gigantic lifts for raising 240 passengers in forty seconds, from more than three times the depth of the Metropolitan Railway to the busy streets above. These splendid lifts, the finest in the world, are now, through the engineering skill of Messrs. Easton & Anderson, like the tunnel, accomplished facts; and their construction and working were tested and reported on in high terms of favor by the Government Inspector, General Hutchinson, a few weeks ago. At the Liverpool end the direct descent to the underground platform of the Mersey Railway is about 90 feet; at the Birkenhead end the depth is something more.
The description of the Liverpool lifts will well suffice also for the Birkenhead lifts. The former are under James Street, where above ground, rising in lofty stateliness, is a fine tower for the hydraulic power, the water being intended to be stored in a circular tank near its summit, the dimensions of which will be 15 feet in diameter and its internal depth 9 feet. From the level of the rails of the Mersey Railway to the bottom of this water-tank the vertical distance is 198 feet. At the western side of the subterranean railway there is, above the arrival platform, a "lower booking-hall," or, more properly, a large waiting room, 32 feet square and 29 feet high, the access to which on this side is by a broad flight of steps rising 12 feet, and to and from which all passengers on the departure platform have communication by a lattice bridge 16 feet above the line of rails. From the western side of this hall the passengers will have access to the three lifts, and will thence ascend in large ascending rooms or cages, capable of containing one hundred persons each, to the upper booking-hall on the ground level of James Street. Intermediate in height between the lower and upper halls the engine-room for the pumps is located. From the lower hall also there is provided, independent of the lifts, an inclined subway, leading up toward the Exchange. In this lower subterranean chamber there are four doorways, 5 feet wide, three of them being fitted with ticket gateways, and leading to the three lift-shafts, excavated in the rock, and lined, where needed, with brick. In each of these shafts, which are 21 feet by 19 feet in sectional area, a handsome ascending wood-paneled room, or cage, formed of teak and American oak, is fitted, its dimensions in plan being 20 feet by 17 feet, and its general internal height 8 feet; but in the central portion the roof rises into a flat lantern 10 feet high, the sides of which are lined with mirrors that reflect into the ascending-room the rays of a powerful gas-lamp. The foundation of this room is a very stiff structure, consisting of two wrought-iron special-form girders crossing beneath it, the cross, 14 inches deep, connecting them being of steel, and forged from a single ingot. The central boss of the cross is 22 inches in diameter, and in this is bored out a central cavity, into which the head of the steel ram, 18 inches in diameter, is fitted; the ram itself being built up of steel cylinders or tubes, 11 feet 3 inches in length, which are connected together by internal screws. There is also a central rod within the ram, as an additional security. The ram descends into a very strong cast-iron cylinder, 21 inches internal diameter, which is suspended in a boring 40 inches internal diameter, and carried down to a depth of over 100 feet in the rock. The two iron girders under the frame of the ascending-room or cage cross the entire lift space, and then at their outer ends are attached to four chains which rise over pulleys fixed about 12 feet above the floor of the upper booking-office. These chains thence descend to suspend two heavy counterweights, so arranged as to work in guides and to pass the ascending-room in the 12 inch interspace between the cage and the side walls of the shaft. These chains are of 1-1/8 inch bar iron, and have each been tested with a load of over 15 tons. The maximum load which can ever come as a strain upon any chain is about three tons. Two chains are attached to each counter-weight, and special attention has been paid to the attachments of these chains to the cage girders. The stroke of each hydraulic lift is 96 feet 7 inches. In the engine-room there are three marine boilers, each 6 feet 6 inches diameter and 11 feet 6 inches long, and three pairs of pumping engines of patented type, each capable of raising thirty thousand gallons of water per hour from the waste tanks below the engine-room to the top tank of the tower above ground. There are three suction and three delivery mains, and these are connected direct to the lifts by a series of change sluices, admirably, neatly, and handily arranged in the engine-room by Mr. Rich, and in such a way that any engine, any lift, or any supply main can be disconnected without interference with the rest of the system. When the tower tank is completed, it alone, under any circumstances, would be able to supply the lifts if every pumping engine were stopped. But if any or all the engines were working, they would automatically assist the top tank, for nominally they will keep the top tank exactly full, and will then stop of themselves. The tower, as we have indicated, is not yet completed, and the pumping engines are consequently doing all the work of the lifts. The ascent and descent of the cages is effected by the attendant who accompanies the passengers, by means of a rope arrangement.
Each cage or room is intended ordinarily to take a maximum freight of 100 passengers, calculated at about 15,000 lb. The hydraulic ram weighs about 11,000 lb., the iron frame and cross of the cage about 6,500 lb., and the cage itself about 13,200 lb., the total being about 30,700 lb. The mass in motion when a cage is fully loaded is estimated at 63,000 lb. dead weight. The journey of elevation will ordinarily be made within one minute, but in the experimental trials which have been made the full journey has actually been accomplished in 32 seconds. In the Board of Trade tests under General Hutchinson, weights to the extent of 15,000 lb. were variously shifted, and in certain cases concentrated in trying localities, but the cage stood the trials without any appreciable change of form, and in neither the cage nor the chains were any objectionable features developed. The three lifts can be worked singly or combined, so that the accommodation is always ready for from 100 to 300 persons. Further railway connections between the Mersey Subaqueous Railway and the surrounding land lines than those which yet exist are in contemplation.
All the booking-halls, waiting-rooms, etc., etc., in connection with the four stations have been laid with Lowe's patent wood-block flooring. The blocks are only 1-1/2 inches thick, but, being made of hard wood and securely fastened to the concrete bed with Lowe's patent preservative composition, they cannot become loose, and will wear for a long series of years, until, in fact, the wood is made too thin by incessant traffic.
The engineer, Mr. Fox, and the architect, Mr. Grayson, are much pleased with the work, especially as it is so noiseless and warm to the feet. These floors ought to be adopted more frequently by railway companies in connection with their station buildings, as "dry rot" and "dampness" are effectually prevented, and a durable and noiseless floor secured.
The Kynoch revolver, manufactured by the Kynoch Gun Factory, at Aston, Birmingham, is the invention of Mr. Henry Schlund. It may be regarded as the most simple in respect of lock mechanism of any existing revolver, whether single or double action. It extracts the cartridges automatically, and combines with this important feature strength and safety in the closing of the breech. Certainty of aim when firing is obtained by means of a double trigger, which serves many purposes. This secures quick repeating as in the double-action revolvers, and at the same time the revolver is not pulled out of the line of sight, as the trigger is pulled off by the forefinger, independently of the cocking motion, the cocking trigger being longer than the ordinary double-action triggers. The cocking trigger further serves to tighten the grasp, and so enables the power of the first recoil, which affects the shooting of all revolvers, to be held in check. The light pull-off enables a steady shooter to make surpassingly fine diagrams.
THE KYNOCH REVOLVER.
THE KYNOCH REVOLVER.
The upper side of the barrel is perfectly free from obstruction, so that the sighting can be done with the greatest ease, and the entire weapon is flush and without projections which can catch surrounding objects, with the exception of the cocking trigger, which seems to require a second guard to render it secure when thrusting the pistol hastily into a holster. At the same time, it should be remembered that the cocking trigger does not effect the firing. It puts the hammer to full cock and rotates the cylinder, and these operations may be performed time after time with safety.
Turning to the mechanical details, it is noticeable that no tools are required to take the weapon to pieces and to put it together. By removing a milled headed screw seen to the left of the general view, every individual part of the lock action comes apart, and can be cleaned and put together again in a few minutes. This screw is numbered 24 in Fig. 4. To load the pistol the thumb piece (marked 2 in Fig. 4 and shown separately in Fig. 3) is drawn back, and thus withdraws the sliding bolt, 3, from the barrel, 20. The barrel and cylinder are then tilted on the pin, 15—a shake will effect this if only one hand be available—and as the chamber rises, the extractor is forced back by the lifter, 15, and the empty shells are thrown out. When the barrel has moved about 80 deg., the spring, 14, which works the lifter, 15, is tripped, and the spring 13 carries the extractor home ready for the fresh cartridge to be inserted. When these are in place, the barrel and cylinder are returned to the position shown in Fig. 1, and are automatically locked by the bolt, 3. All is then ready for firing. The middle finger is placed on the cocking lever, and the forefinger within the trigger guard. The cocking trigger is drawn back, taking with it the firing trigger for the greater part of its stroke. At the same time the lifter, 8, which is pivoted to the cocking lever, engages with a ratchet wheel (seen in Fig. 2) attached to the cylinder, and rotates it through one-sixth of a revolution. To insure the exact amount of rotation, a heel on the trigger, not to be seen in the engravings, engages in one of the six slots (Figs. 1 and 2) formed round the barrel. The end of the slot is square, and comes up against the heel, which tightly grips the cylinder, and holds it steady while firing. A toe-piece, just over the figure 4, in Fig. 3, holds the cylinder when the cocking trigger is in its normal position. The cocking lever also compresses the main spring, 7, and holds it in this state until the firing trigger, 12, is pressed by the forefinger against the sear, 9, and the hammer, 5, is driven forward against the cartridge. If the pistol be not fired, the release of the cocking trigger takes the pressure off the spring, and there is thus no danger of accidental discharge.
It will thus be seen, saysEngineering, that the weapon presents many advantages. It can be loaded on horseback when one hand is engaged with the reins; there is nothing to obstruct the aim, and the act of firing does not throw up the muzzle, for the two operations of cocking and shooting are separate, and consequently the latter needs only a very light pressure of the finger to effect it. The breech is well protected, so that the flash from a burst cartridge cannot reach the face of the user. The mechanism is as nearly dust proof as possible, and can be entirely taken to pieces and cleaned in a few moments, and the whole forms as handy a weapon as can be desired, where rapid and accurate shooting is required.
An interesting feature of the International Exhibition at Antwerp was the competition which was invited between different forms of mechanical motors on tramways for use in towns, and between different forms of engines for use on light railways in country districts, or as these are termed, "Chemins de Fer Vicinaux."
These latter have obtained a considerable development in Belgium, Italy, and other Continental states; and are found to be most valuable as a means of cheapening the cost of transit in thinly peopled districts. But owing to the fact that the Board of Trade regulations in this country have not recognized a different standard of construction for this class of railway from that adopted on main lines, there has been no opportunity for the construction of such lines in England.
There has, however, been a great development of tramway lines in England, which in populous districts supply a want which railways never could fully respond to; and although hitherto mechanical traction has not attained any very considerable extension, it is quite evident that if tramways are to fullfil their object satisfactorily, it must be by means of mechanical traction.
It is also certain that the mechanical motor which shall be found to be most universally adaptable, that is to say, most pliant in accommodating itself to the various lines and to the varying work of the traffic, will be the form of motor which will eventually carry the day.
The competition between different forms of motors at the Antwerp Exhibition, which was carefully superintended, and which was arranged to be carried on for a reasonable time, so as to enable the qualities and defects of the different motors to be ascertained, affords a starting point from which it will be possible to carry on future investigations.
I have, therefore, thought it advantageous to the interests of the community in this country to bring the results arrived at before this Society; and as the "Chemins de Fer Vicinaux," to which one part of the competition was devoted, have no counterpart in this country, it is proposed to limit the present paper to an account of the experiments made on the motors for tramways.
Certain conditions were laid down in the programme published at the opening of the Exhibition, to regulate the competition, in order that the competitors might understand the points which would be taken into account by the judges in awarding the prizes.
The experiments were made upon a line of tramway laid down for the purpose in the city of Antwerp, carried along the boulevards from near the main entrance of the exhibition to the vicinity of the principal railway station, a distance of 2,292 meters.
The line ended in a triangle of 505 meters, in order that those motors which required to run always in the same direction should be enabled to do so.
Out of the whole length of the line, viz., 2,797 meters, 2,295 meters were in a straight line, 189 meters in curves of 1¾ chains radius, and 313 meters in curves of 1 chain radius. There were on the line four passing places, besides a passing place at the terminus; these were joined to the main line by curves of 1¾ chains radius.
The line was practically level, the steepest incline being 1 in 1,000; this circumstance is somewhat to be regretted, but the city of Antwerp afforded no convenient locality where a line with steep gradients could have been obtained. The motors were kept in sheds close to the commencement of the line of tramway near the exhibition, where all necessary cleaning and such minor repairs as were required could take place.
A regular service was established, according to a fixed time-table, to which each motor was required to conform. Each journey was reckoned as starting from the end near the exhibition, proceeding to the beginning of the triangle, and returning to the starting point. An hour was allowed between the commencement of each journey, fourteen minutes were allowed for a stoppage at the end near the exhibition, and eighteen minutes at the other end—thus allowing twenty-eight minutes for traveling 2 miles 1,500 yards, or a traveling speed of about 6 miles an hour. The motors were required to work four days out of six, and on one of the four days to draw a supplementary carriage.
An official, assisted by a storekeeper, was appointed to keep a detailed record—
1. Of the work done by each of the motors.2. Of any delays occurring on the journey, and of thecauses of delay.3. Of the consumption of fuel, both for lighting thefires and for working.4. Of the consumption of grease.5. Of the consumption of water.6. Of all repairs of whatever nature.7. Of the frequency of cleaning and other necessaryoperations required for the efficient service of themotor.
The experiments lasted about four months. Five competitors offered themselves, which may be classed as follows: Three were propelled by the direct action of steam, and two were propelled by stored-up force supplied from fixed engines.
Propelled by the direct action of the steam.1. The Krauss locomotive engine, separate from the carriage.2. The Wilkinson locomotive engine (i.e., Black andHawthorn), also separate from the carriage.3. The Rowan engine and carriage combined.Propelled by stored-up force.4. The Beaumont compressed-air engine.5. The electric carriage.
It is somewhat to be regretted in the public interest that other forms of mechanical motors, such as the Mekarski compressed-air engine, or the engine worked with superheated water, or cable tramways, or electrical tramways, were not also presented for competition.
1. The Krauss locomotive is of the general type of a tramway locomotive, but with certain specialties of construction. It has coupled wheels. The weight is suspended on three points. The water-tanks form part of the framing on each side; a covering conceals all except the dome of the boiler. Above the roof is a surface condenser, consisting of 108 copper tubes placed transversely, each of which has an external diameter of 1.45 inches. The boiler is similar to that of an ordinary locomotive; its axis is 3 feet 10½ inches above the road. The body of the engine is 9 feet 11 inches long, and 7 feet 2½ inches wide. The axles are 4 feet 11 inches from center to center. The platform extends along each side of the boiler; the door of the fire-box is in the axis of the road. The engine driver stands on the right-hand side, in the middle of the motor, where he has command of all the appliances for regulating the movements of the engine as well as of the brake.
The Wilkinson (Black and Hawthorn) engine had a vertical boiler and machinery. The cylinders were on the opposite side of the boiler from the door of the fire box, and mounted independently; the motion of the piston was communicated by means of a crank shaft and toothed wheels to the driving axle. The wheels were coupled. A regulator, injector, and a hand-brake were placed at each end, so that the engine driver could always stand in the front, whichever was the direction in which the engine moved; and there was a platform of communication between the two ends, carried along one side of the boiler.
The boiler was constructed with "Field" tubes, the horizontal tube plate having a flue in the middle which carried the heated gases into the chimney.
The visible escape of the steam is prevented by superheating. To effect this, the steam, as it leaves the cylinder, passes into a cast iron chamber adjacent to the boiler, which is intended to retain the water carried off with the steam. From thence the steam passes into a second chamber, suspended at a small height above the grate in the axis of the boiler and of the flue which conveys the heated gases into the chimney, and thence into a sort of pocket inclosed in the last-mentioned chamber, which is open at the bottom, and the upper part of which terminates in a tube passing into the open air. This method of dissipating the steam avoids the necessity of a condenser; but if it be admitted that the steam in escaping has a minimum temperature of 572° Fahr., it will carry away 12 per cent. more caloric than would have been required to raise it to a pressure of 150 lb. per square inch.
The steam escaping through the safety valve is passed through the same apparatus.
The toothed wheel on the driving axle is arranged to act upon another toothed wheel on a shaft connected with the regulator, so as to control its speed automatically.
The length of the engine is 10 ft. 10 in., its width 5 ft. 9 in., and the distance from center to center of the wheels 5 ft. 2 in.
The Rowan tram-car consists of a body 31 feet long and 7 feet wide, resting on a two-wheeled bogie behind and on a four-wheeled bogie in front, this front bogie being the motor, and the whole has the appearance of a long railway carriage, somewhat in the form of an omnibus with a platform at each end, of which the front platform is occupied by the engine. It requires, therefore, either a turntable or a triangle at the end of the line, so as to enable it to reverse its direction.
This motor is a steam engine of light and simple form, supplied with steam from a water tube boiler with very perfect combustion, so that no smoke escapes. The boiler is somewhat on the principle of a Shand and Mason boiler; it is so built that It can easily be opened and every part of the interior examined and cleaned.
The peculiarity of the Rowan motor is the simplicity of the attachment of the engine to the carriage, and the facility with which it can be detached when required for cleaning or repair, viz., in five or six minutes.
The steam can be got up in the engine with great rapidity if a change of engine is required. When, however, the engine is detached, the carriage loses its support in front, and is therefore not serviceable. When necessary, the combined motor can draw a second ordinary carriage.
The motor by itself occupies a length of 9 ft. 8 in. It has two horizontal cylinders; the four wheels of the bogie are coupled, and between the wheels the sides of the framing are rounded to allow two vertical boilers to stand. These boilers have vertical tubes for the water, which are joined together at the top by a horizontal cylinder. Each boiler, with its covering, is 1 ft. 9 in. in diameter. The boilers stand 1 ft. 9 in. apart, thus affording space between them for the motive machinery, including the pump. The crank axle is behind the boilers. The levers, the injector, the access to the fire-box, a pedal for working the engine brake as well as a screw brake for the carriage, are all in front. The brakes act on all six wheels, are worked by the driver, and the whole weight of the engine, car, and passengers being carried on these wheels, the car can be stopped almost instantaneously; and as over two-thirds of the entire weight of the car and passengers rests on the four driving wheels; there is always sufficient adhesion on all reasonable inclines, and the adhesion is augmented as the number of passengers carried increases. Hence this car is adapted for lines with heavy grades.
A small water tank is attached to the framing; two small boxes for coal or coke, with a cubic capacity of about 3½ feet, are attached to the plate in front of the bogie. The covering of the boilers is in two parts, which are put on from each side horizontally, and screwed together in the center. The removal of the upper part enables the tubes to be examined and cleaned. The draught is natural; the base of the chimney is 3 ft. 2 in, from the grate; the height of the chimney is 5 ft. 2 in.
The steam from the cylinders passes directly into a condenser placed on the top of the carriage. The condenser is made of corrigated copper sheets millimeter thick. Two sheets, about 15 to 18 inches wide and 15 feet long, are laid together and firmly soldered, forming a chamber. Twenty of these chambers are placed side by side on the top of the carriage, connected with a tube at each end, so as to allow the steam to pass freely through them. The lower corrugations in the several chambers are connected together, and thence a pipe with a siphon to stop the steam is carried to a water tank under the carriage, which thus receives the condensed water. This arrangement afforded a condensing surface of about 800 square feet. It should be mentioned that with larger engines Mr. Rowan employs as much as 1,600 feet of condensing surface. The nearness of the chambers to each other tends no doubt to diminish the power of condensing the steam, but this is somewhat compensated by the artificial circulation of air produced by the movement of the carriage. But in any case, if there is surplus steam, the pipe from the condenser causes it to pass under the grate, whence it rises superheated and invisible through the fire and up the chimney.
Under the carriage attached to the framing are four reservoirs, holding about three and a half cubic feet of water, of which water space one-half acts as a reservoir for cold feed water, and half for the condensed water. A tube from the small reservoir on the engine communicates through valves with the reservoirs of hot and cold water on the carriage.
The consumption of cold water measured during two days was 2.86 lb. per kilometer; assuming that the boiler evaporated 6.5 lb. of water per pound of coal, the cold water formed one-fifth of the total feed water required.
The carriage, i. e., the part occupied by passengers, is 21 ft. 8 in. in length. It holds seats for forty-five passengers, besides those who would stand on the gangway and platform. The seats are placed transversely on each side of a central corridor, each seat holding two people. The platform of the carriage is about 2 ft. 6 in. above the rails. Passengers have access to the interior from behind by means of the end platform, and in front near the engine from the two sides. As already mentioned, the hind part of the carriage rests upon two wheels, the front part being, as already mentioned, supported on the engine bogie. To effect this support, the hinder part of the framing of the engine is formed in a half circle, with a broad groove, in which the ends of two springs are arranged to slide. The centers of the springs form the support of the framing of the carriage.
The framing of the engine bogie is attached to the hind bogie truck of the carriage by two diagonal drawbars. The coupling is effected by bolts close to the engine, and the car is drawn entirely by means of the bogie pin of the hind bogie. The trucks are 16.5 ft. apart.
Table I. above shows the dimensions of different parts of these three steam motors, as well as their weights.
The Beaumont engine, worked by compressed air, may be generally said to be similar to that described in a paper read before the Society of Arts on the 16th March, 1881, to which, however, some improvements have been since introduced.
The apparatus for compressing the air was placed in the shed. The air was compressed to 63 atmospheres by a pump worked by a steam engine, and stored in cylindrical reservoirs of wrought iron without rivets. A pipe led the air from the reservoirs to the head of the tramway, where the cylinder placed on the motor for storing the air during the journey could be conveniently charged.
The air was compressed by means of four pumps, placed two and two in a water-box, and worked by the direct action of a compound engine, with cylinders, placed in juxtaposition, of 8 in. and 14 in. diameter respectively, with an equal length of stroke of 13 in.
TABLE I.Krauss. Wilkinson. Rowan.Diameter of cylinder.........d5.5 in. 6.5 in. 5.1 in.Length of stroke.............l11.8 in. 9 in. 9.8 in.Diameter of wheels...........D31.5 in. 27.5 in. 29.5 in.Pressure at whichboiler is worked...........P220 lb. 147 lb. 191 lb.(p(d²)l)/(2D)................E1,210 lb. 1,509 lb. 805 lb.Total heating surface........S105 sq. ft. 105 sq. ft. 64 sq. ft.Grate surface................G2.7 sq. ft. 5.4 sq. ft. 3.1 sq. ft.Surface of condenser.........C274.482 s. ft. None. 861.120 s. ft.Weight in running order(motor only)...............P'15,400 lb. 15,400 lb. 9,020 lb.Weight in running order(total)....................P"- - 15,400 lb.Contents of water tank.......-28.24 cub. ft. 13 cub. ft. 4.2 cub. ft.Contents of coal bunks.......-14.12 cub. ft. 12.5 cub. ft. 8.5 cub. ft.P'/E12.7 lb. 10.2 lb. 11.2 lb.P"/E- - 19.125 lb.P'/S146 147 140P'/G5,722 2,855 2,889C/S2.6 - 13.4C/G102 - 275
The air, after being forced through the first pump cylinder, passed successively through the other three, the diameters of which were of proportionately decreasing sizes, viz., 8.2 in., 5 in., 3.5 in., and 2 in., and the air on leaving each cylinder passed on its way to the next cylinder through a coiled pipe immersed in flowing water to remove the heat generated. This cooling surface amounted to nearly 54 sq. ft.
The cooling of the air was very efficient. In an experiment made on this question, the temperature of the compressor did not vary to the extent of 9° F. in charging the reservoir from 40 to 63 atmospheres, occupying an hour and a half, the consumption of water during the time being about 1,400 gallons.
The fixed reservoirs were of about 240 cubic feet capacity.
The motor formed part of a compound vehicle, which may be said to have consisted of two parts joined together by an articulated corridor, the whole being covered by a roof which was approached from the platform behind by an easy staircase. On this roof were seats for outside passengers.
The front part of the compound vehicle contained the motor, as well as a compartment for six inside passengers, with roof space for twenty passengers, and weighed about 15,400 lb. when empty; the hind part contained accommodation inside for twelve passengers, and outside for fourteen passengers, and weighed 6,600 lb.
The combined vehicle was entered from the platform in the rear, which could hold four passengers, and from thence, as already mentioned, the staircase led on to the roof. The total number of passengers this vehicle could accommodate was thus eighteen inside, thirty-four on the roof, four on the platform, or fifty-six in all.
The total length of the carriage was 29 ft. 7 in., the width 7 ft. The distance between the axes of the bogies was 16 ft. 9 in. The distances apart of the centers of the wheels were in the case of the hind bogie 3 ft. 9 in., and in the case of the front bogie 4 ft. 4.6 in.
The motor is a compound engine, the diameters of the cylinders being 4.9 in. and 1.9 in., with a 12 in. stroke. The diameter of the wheels was 2 ft. 4 in. A small boiler is placed on one side, in front, for creating steam, which passes into a steam-jacket, inclosing the pipe of communication from the reservoir to the cylinders, as well as the cylinders themselves, so that the air was warmed before it escaped. The reservoirs on the motor contained 71 cubic feet.
In an experiment made on charging the reservoir in the motor, the pressure in the fixed reservoirs, at the time of charging the reservoirs on the motor, was 63.8 atmospheres, at a temperature of 68° F. One atmosphere was lost by letting the air into the pipe laid between the shed and the tramway where the motor stood; when the reservoir on the motor was charged, the pressure fell to 42.6 atmospheres in the fixed reservoirs, at a temperature of 55° F.
The pressure in the reservoir on the motor, when ready to start, was 42.6 atmospheres, at a temperature of 84° F. On its return, at the end of forty-six minutes, after a journey as above mentioned of about three and a quarter miles including the triangle, the pressure had fallen to 20.9 atmospheres, and the temperature to 71° F. The weight of air used during the journey was thus about 110 lb., or, say, 34 lb. per mile. The coal consumed by the stationary engine to compress the air amounted to 39 lb. per mile, in addition to 3 lb. of coke per mile for warming the exhaust.
While the motor was performing its journey, the stationary steam-engine was employed in raising the pressure in the fixed cylinders to 63 atmospheres, and worked, on an average, during fifty minutes in each hour; during the rest of the journey it remained idle. It was thus always employed in doing work in excess of the pressure which could be utilized on the car, and the work was, under the circumstances of the case, necessarily intermittent. This was a very unfavorable condition of working.
In the electric tram-car the haulage was effected by means of accumulators. The car was of the ordinary type with two platforms. It was said to have been running as an ordinary tram-car since 1876. It had been altered in 1884 by raising the body about six inches, so as to lift it clear of the wheels, in order to allow the space under the seats to be available for receiving the accumulators, which consisted of Faure batteries of a modified construction. The accumulators employed were of an improved kind, devised by M. Julien, the under manager of the Compagnie l'Electrique, which undertook the work.
The principal modification consists in the substitution, for the lead core of the plates, of one composed of a new unalterable metal. By this change the resistance is considerably diminished, the electromotive force rises to 2.40 volts, the return is greater, the output more constant, and the weight is considerably reduced. The plates being no longer subject to deformation have the prospect of lasting indefinitely. The accumulators used were constructed in August, 1884.
The car, as altered, had been running as an electric tram-car on the Brussels tramways since October, 1884, till it was transferred to the experimental tramway at Antwerp. The accumulators had been in use upon the car during the whole of this period, and they were in good order at the end of the experiments, that is to say, when the exhibition closed at the end of October, 1885.
The accumulator had forty elements, divided into four series, each series communicating, by means of wires fixed to the floor of the car, with commutators which connected them with the dynamo used as a motor.
There were two sets of these batteries or accumulators, one of which was being charged in the shed while the other was in use. The exchange required ten minutes, including the time for the car to go off the tramway into the shed and return to the tramway. This exchange took place after every seven journeys. Therefore, the two batteries would have sufficed for working the car over a distance of about forty-two miles during sixteen hours.
It may be observed that the first service in the morning would be performed by means of the accumulators charged during the afternoon and evening of the previous day.
Each element of a battery was composed of nineteen plates, of which nine were positive, four millimeters thick, and ten negative, three millimeters thick. Each positive plate weighed 1.44 lb., of which about twenty-five per cent. consisted of active material. Each negative plate weighed nearly 1 lb., of which one-third consisted of active matter. The weight of the metallic part of the battery amounted, therefore, to 1,846 lb.; and the whole battery, including the case and the liquid, amounted to 2,464 lb., which contained 499 lb. of active matter, or about 20.25 per cent. The four cases in which the battery was contained were so arranged as to divide the weight equally between the wheels.
Two commutators inclosed in a box were placed on the platforms at the two ends of the carriage, so as to be available for moving in either direction.
The accumulators were divided into four series of ten double elements, which, by means of the commutators, could be united under four combinations, viz.:
1st. 4 series in quantity—1 in tension.2d. 2 " " " 2 "3d. 3 "4th. 4 "
Finally, a fifth movement united the four series in quantity, coupling them on each other, and putting the dynamo out of circuit, thus restoring equilibrium. When in a state of repose, the handle was so arranged as to keep this latter switch turned on. The accumulators were arranged for charging in two series united in quantity, each containing twenty double elements. The charge was effected by a Gramme machine, worked by a portable engine. Each of these series received its charge during seven hours for the ordinary service of the car, and during nine hours for the accelerated service.
The accumulators on the car actuated a Siemens dynamo, acting as a motor, such as is used for lighting, having a normal speed of 1,000 revolutions, fixed on the frame of the carriage. The motion was conveyed from the pulley on the dynamo by means of a belt passing round a shaft fixed on movable bearings to regulate its tension, and thence to the axles by means of a flat chain of phosphor bronze. The chain was adopted as the means of moving the axle, on account of its simplicity and facility of repair by unskilled labor.
The speed was fixed at 4 meters per second (which corresponds with a speed of nearly 9 miles per hour) for 1,000 revolutions of the dynamo; and it was regulated by cutting a certain number of the accumulators out of circuit, instead of by the device of inserting resistances, which cause a waste of energy. By breaking the circuit entirely the motive power ceased, and the vehicle might either be stopped by the brakes or allowed to run forward by gravity, if the road were sufficiently inclined. The reversal of the motor was effected by means of a lever which reversed the position of the brushes of the dynamo.
The dynamo could be set in motion, and the carriage worked from either end, as desired. The handle to effect this was movable, and as there was only one handle, and this one was in charge of the conductor, he used it at either end as required.
It should be mentioned that the car was lighted at night by two incandescent lamps, which absorbed 1.5 amperes each; and the brakes also were worked by the accumulators.
The weight of the tram-car was 5,654 lb.; the weight of the accumulators was 2,460 lb.; the weight of the machinery, including dynamo, 1,232 lb. The car contained room for fourteen persons inside and twenty outside. Under the conditions of the competition the car was required to draw a second car occasionally.
The jury made special observations upon the work required to move the car between the 20th September and 15th October, 1885. Seals were attached to the accumulators. Moreover, from the 27th of September, after each charge, seals were placed on the belts from the steam-engine to prevent any movement of the Gramme machine, so that there could be no charges put into the accumulators beyond those measured by the jury.
The instruments used for measuring were Ayrton's amperemeter and Deprez's voltmeter, which had been tested in the exhibition by the Commission for Experiments on Electrical Instruments, under the presidency of Professor Rousseau. Besides this, Siemens' electro-dynamometer and Ayrton's voltmeter were used to check the results; but there was no practical difference discovered. During the period of charging the accumulators, the intensity of the current and the electromotive force was measured every quarter of an hour, and thence the energy stored up in the battery was deduced. It may be mentioned that the charge in the accumulators, when the experiments were commenced, was equal in amount to that at their termination.
An experiment was made on 21st October to ascertain, as a practical question, what was the work absorbed by the Gramme machine in charging the accumulators. The work transmitted from the steam-engine was measured every quarter of an hour by a Siemens dynamometer; at the same time the intensity of the electromotive force given out by the machine, as well as the number of the revolutions it was making, was noted. It resulted that for a mean development of 4 mechanical horse power, the dynamometer gave into the accumulators to be stored up 2.28 electrical horse power, or 57 per cent. The intensity varied between 25.03 and 23.51 amperes during the whole time of charging. Of this amount stored up in the accumulators a further loss took place in working the motor; so that from 30 to 40 per cent. of the work originally given out by the steam-engine must be taken as the utmost useful effect on the rail.
It was estimated that to draw the carriage on the level 0.714 horse power was required, or if a second carriage was attached, 0.848 horse power would draw the two together. This would mean that, say, 2 horse power on the fixed engine would be employed to create the electricity for producing the energy required to draw the carriage on the level.
The electric tram-car was quite equal in speed to those driven by steam or compressed air, and was characterized by its noiselessness and by the care with which it was manipulated.
Assuming the car, by itself, cost the same as an ordinary tram-car, the extra cost relatively to other systems was stated as being according to the following figures, viz.: the Gramme machine cost £48, the motor £208, and the accumulators 2.25 francs per kilogramme (10d. per pound). To these must be added the cost of erection, and of switches for manipulating the current; as well as the proportion of the cost of a fixed engine to create the electricity.
Having thus given a general description of the various motors which were presented for competition, I will now give a brief summary of some of the principal particulars obtained during the competition. In the first place, it may be mentioned that the jury consisted of the following:
President.—M. Hubert, Ingénieur en Chef, Inspecteur de Direction à l'administration des chemins de fer de l'Etat Belge.
Vice-President.—M. Beliard, Ingénieur des Arts et Manufactures, délégué par le Gouvernenent Français.
Members.—MM. Douglas Galton, Capitaine du Génie, délégué par le Gouvernement Anglais; Gunther, Ingénieur, Commissaire Général de la Section allemande à l'Exposition d'Anvers; Huberti, Ingénieur à l'administration des chemins de fer de l'Etat Belge, Professeur à l'Université de Bruxelles; Dery, Ingénieur Chef de service à l'administration des chemins de fer de l'Etat Belge.
Secretary.—M. Dupuich, Ingénieur Chef du service du matérial et de la traction à la Société Générale des chemins de fer économiques.
Reporter.—M. Belleroche, Ingénieur en Chef, à la traction et au matérial des chemins de fer du Grand Central.
Members added by the Jury.—MM. Vincotte, Ingénieur, Directeur de l'Association pour la surveillance des machines à vapeur; Laurent, Ingénieur des mines et de l'Institut électro-technique de l'Université de Liége.
The original programme of the conditions which were laid down in the invitation to competitors, as those upon which the adjudication of merit would be awarded, contained twenty heads, to each of which a certain value was to be attached; and, in addition to these special heads, there were also to be weighed the following general considerations, viz.:
a. The defects or inconveniences established in the course of the trials.
b. The necessity or otherwise of turning the motor, or the carriage with motor, at the termini.
c. Whether one or two men would be required for the management of the engine.
As regards these preliminary special points, the compressed air motor, as well as the Rowan engine, required to be turned for the return journey, whereas the other motors could run in either direction.
In regard to this, the electric car was peculiarly manageable, as it moved in either direction, and the handle by which it was managed was always in front, close to the brake. This carriage was the only one which was entirely free from the necessity of attending to the fire during the progress of the journey, for even the compressed air engine had its small furnace and boiler for heating the air.
Each of the motors under trial was managed by one man.
The several conditions of the programme may be conveniently classified in three groups, under the letters A, B, C. Under the letter A have been classed accessory considerations, such as those of safety and of police. These are of special importance in towns. But their relative importance varies somewhat with the habits of the people as well as with the requirements of the authorities; for instance, in one locality or country conditions are not objected to which, in another locality, are considered entirely prohibitory.