speed, no matter how the actual feeding at the boiler fronts is being operated. As shown in the diagram, two 44-inch pipes start from the two extractors, belonging to the second hot well, the one passing along the first floor boilers, the other along the second floor boilers. These meet and connect with the pipe from the two other pumps at the west end of the first floor boiler room. The boilers are connected by 2-inch pipes and valves to these headers and to the blow-off pipes, as indicated in Fig. 2. A secondary line has been provided for the first floor boilers of two 24-inch pipes, running along the back of the boilers, and communicating with the railway feed pumps and pipe ends A at the front of the boilers, to guard against accident to the main feed pipes. Boilers.-There are eighten boilers of the Galloway internal double flue type, with all the latest American improvements, manufactured with special reference to the work required, by the Edge-Moor Iron Company, of Edge Moor, Delaware, for a working pressure of 160 pounds, capable of generating 250 h. p. at 15 pounds per h. p. hour; this is the estimated quantity required for the triple compound engines of the Edison type at their maximum efficiency point. The boilers are 27 feet in length by 7 feet in diameter and have a flue space all around the shell enclosed with sheet iron, mineral wool and brick, making a very efficient battery. The flues of the boilers on each of the two floors are divided so that one half go to one stack Fig. 4. The boilers are also fitted with direct forced draft which can be used when necessary without interfering with the ordinary firing. Some of the boilers have now been in operation for over two years, and up to the present time have required absolutely no repairs; only one tube has started to leak and that was due to a blister in the material. It may also be here stated that at the time of adopting these boilers they were the only ones on the market cap able of supplying steam at high working pressure. Forced Draft-The stacks, being only 125 feet high on account of the unstable ground upon which they are built may, under unfavorable conditions prove insufficient to produce the necessary draft, and forced draft apparatus has accordingly been installed. This consists of four 60 inch fans driven by 5 x 4 inch double upright direct coupled steam engines, manufactured by B. F. Sturtevant, of Boston, Mass. The air is taken from the different parts of the building where heated air is likely to accumulate, thus greatly aiding the ventilation, and is forced into two large sheet iron conduits which connect under the fire-room directly, with the furnace. The system is divided into two complete sections which are interchangeable. Coal Storage and Ash Handling Apparatus.-The problem of storing and handling coal was a difficult one, owing to the contracted space available, and its solution has been remarkably happy. The coal is taken either from the street, where it is unloaded through an opening in the FIG. 4.-COAL STORING AND ASH HANDLING APPARATUS. side-walk, into the basement, and lifted by elevators to the top floor, or, it may, by means of a second elevator on the river side, be directly hoisted from barges to the main large coal bin on the upper floor, whence it is distributed by a reversible conveyer. From this bin, or bunker, it descends by gravity through small channels to the other bins alongside the south wall in front of the two boiler batteries, as shown in Fig. 4. The storing capacity of the bins is about 600 tons. The ashes are taken away from the front of the boilers through conduits and delivered by elevators into bins at each end of the building where they descend by gravity either to wagons on the street or to barges on the river. The conveyers and elevators both for the coal storage and ash handling apparatus are driven by electric motors. The plant was installed by the Link-Belt Machinery Company, of Chicago, Ill. Steam Piping.-A diagram of the steam piping is shown. in Fig. 5. The boilers are connected by 7 inch wrought iron pipes with large copper bends to two 16 inch headers, running along the south wall of the engine room and connected by three vertical pipes. From the upper header the steam is led to two sub-headers, 12 and 16 inches in diameter, respectively, from which it branches to the engines. Copper has been very extensively used to secure sufficient elasticity, and by well placed valves it is possible to shut off any part of the piping independently. Before entering the engines the . steam passes through a centrifugal trap to be relieved from all entrained and condensed water. All flanges were specially designed for the high pressure used and are faced, turned and connected by fitted bolts. All joints are of brass wire gauze and litharge cement, and are in first class condition, and all piping and connections are covered with magnesia non-conducting blocks. THE COPPER-ZINC ACCUMULATOR.-V. (Concluded.) Daul Schoop A NEW PROCESS OF MAKING COPPER ANODES WITH POROUS SURFACES. As has already been set forth, the active material for the copper electrode, is applied mechanically to a copper support; while Desmazures uses spongy copper, which he applies by means of great pressure to a net-work of copper wire, Phillips and Entz make use of finely ground oxide of copper, which is pressed as a paste into the meshes of a copper cable. So far, both proceedings are very similar to the well-known process of "pasting" lead plates, covered by Faure's and Brush's patents. It might also be possible to render a copper electrode porous by an electrolytic process, similar to Planté's invention, for instance, but perhaps the best and most practical way is the following: At ordinary temperatures, copper does not readily combine with oxygen, except in a very finely divided powder and the facility for combining increases at higher temperatures. Solid copper, either cast or wrought, begins to absorb oxygen at a temperature near 400 degrees C., and is covered by a black coating of oxide of copper. But this layer protects the subjacent copper from further contact with oxygen and prevents the deeper penetration of oxygen. If the temperature is raised, say, to a full red heat, the black oxide of copper reacts upon the metallic support, giving part of the oxygen off and forming suboxide of copper. If now, at the same time, air or oxygen is permitted to circulate around the copper piece, the effect is that its surface can be oxidized to any desired depth; even so far that no more metallic copper is left, but the whole is transformed into oxide of copper. This is not, however, what is wanted for our purpose. The surface should be oxidized to or of an inch and have a metallic support left of sufficient conducting power. To perform the desired result is a matter of maintaining the proper degree of heat; since the right temperature is very near the point where the oxide of copper fuses, some care has to be taken to prevent too high a temperature. One great drawback will be found, and that is, that while the article is cooling down, the oxide of copper blisters and cracks off; the contraction of the oxide of copper is different from that of the metallic copper and therefore the brittle oxide detaches itself from the metallic core. It is still possible, however, to attain a practical result. Before that point is reached at which the oxide cracks off the surface, it can be reduced to copper by contact with, for instance, carbonic oxide. The porous copper thus formed, adheres firmly to the solid core, and repeating the process once or twice, the porosity of the superficial layer can be brought to any desired degree. Of course, the second time, the temperature for effecting the combination with oxygen is much lower, only about 300 degrees C., and there is no more cracking off of oxide, or the temperature may be chosen so low as only to allow the formation of suboxide of copper; in this latter case the copper electrode is quite ready for use in the accumulator. This process for making porous copper electrodes may be advantageously carried out with the aid of the apparatus described below, and which is shown in the shown in the dia gram. In the centre of the cylindrical furnace is placed a muffle м of refractory material, such as magnesia or china clay. This muffle has a false, perforated bottom в and a perforated cover c. Below the false bottom there are two inlets A and A'; A is for the supply of air, a' for the supply of carbonic oxide or generator gas. P is a partition wall of insulating material, like asbestos or any other refractory substance. The generator G, which surrounds the muffle and partition wall is filled with coke by the supply-holes z. A chimney K surmounts the generator. The copper is first put in the muffle and raised to the necessary red heat, while air is introduced through the inlet A. When the copper is sufficiently and uniformly oxidized, the air is stopped and the generator cooled down by blowing steam through the pipes w. At the proper time, the inlet a' is opened and carbonic oxide or the water gas produced in the generator, is let into the muffle, where it reduces the copper oxide to porous copper. This operation is then repeated, but at much lower temperatures, in order to obtain the desired porosity of the layer. After a little practice, it is possible to treat a large amount of copper each day in this way. The time of the whole treatment is about three hours. There is, perhaps, no cheaper and more rapid way for rendering copper porous, but there are still other interesting points connected with this method. 1. The layer of porous copper adheres so firmly to the could be compared with it. The copper may be bent many core of the electrode, that no mechanically applied layer times and in all directions without detaching the layer. tion, without interfering with the application of the porous 2. The form of the copper electrode may be of any descriplayer. It need not be a wire netting or loosely made cable or a grid or any special form adapted to retain the active material firmly. For several reasons, a plain copper sheet is the most desirable form. 3. An electrode, made according to this process, does not infringe any patents, covering the mechanical application of active material to a support (paste, paint or cement). lytic process, because no chemicals are used and the air 4. The heating process must be cheaper than any electroand generator-gas are the cheapest agents possible. 5. The labor and hand work is almost entirely eliminated. After the copper electrode has been treated, it must be covered or surrounded by a partition or membrane; since it is very doubtful whether organic substances like cotton likely to stand the action of the strong caustic electrolyte (cellulose) or parchment paper (hydro-cellulose) are without injury to the cell. The copper electrode is put preferably in a porous pot made of magnesia. The magnesia the measurements. This clearly showed the presence of pin holes, flaws and a non-homogeneous coating of the insulating material, a state of affairs that recent tests show to be rapidly disappearing with the modern improvements in manufacture to meet various requirements. This inferior or uncertain quality of insulation continued to pour in until December, 1892, but from that date up to the present time a wonderful improvement has been noted and the tests on all samples, submitted by over fifteen different manufacturers, show that in no case has the insulation resistance dropped lower than 220 megohms, after having been submerged in water for fourteen days and then in lime paste for three days, and each reading being made with a potential of 550 volts; while several samples showed a resistance of over 4,400 megohms after the same severe test. We thus see that the manufacturer has more than met the insurance requirements and it is certainly very gratifying to both parties to note the steady improvement in the manufacture of insulated wire upon which depends the safety of our buildings and the lives of our linemen, as the insulation requirements hold good for outside as well as interior conductors. TIAL VARIABLE SPEED DYNAMO. EVERY piece of insulated wire that is to be used for lighting or power purposes in the city of Boston has to be subjected to a very careful insulation test before it can be used in any building within the city limits. This test is made by the Boston Fire Underwriters Union, and a similar test has to be made for the New England Insurance Exchange THE LEWIS SELF REGULATING CONSTANT POTENbefore they will pass upon its use in any building in New England, outside of Boston. Although neither board can enforce the removal of a single piece of disapproved wire or wiring they can so add to the insurance rate on the building in which the wiring is done that the owner soon comes to the conclusion that there is really danger of fire and out comes the bad work which is replaced by good wire and good workmanship. Electric lighting, as we all know, is the safest mode of illumination when properly installed; yet there is nothing so likely to set fire to a building as electricity when carelessly handled. With the knowledge of this fact the insurance companies, all over the country, have adopted rules which have been very carefully compiled by men of long and varied experience in electrical construction work and as every piece of wiring, either for lighting or power, is now thoroughly inspected before the current is turned on in the building, and due to the fact that we are getting better wire and fixtures every year, it is safe to say that there is no possible chance of a fire from electricity if the wireman and inspector does his duty according to the present rules and requirements. Although we have had numerous makes of insulated wire for a number of years it is only within the last two years that we have had uniformly excellent wire insulation. Not that we have not always had the insulating material but the method of manufacture has been crude. Rule 12, of the Rules and Requirements of the Boston Fire Underwriters Union, state that : "Insulation that will be approved for interior conductors must be solid, at least of an inch in thickness and covered with a substantial braid. It must not readily carry fire, must show an insulation resistance of one megohm per mile after two weeks submersion in water at 70 degs. Fahrenheit, and three days submersion in lime water, with a current of 550 volts and after three minutes' electrification." Every test on samples of insulated wire, furnished by over fifty manufacturers, has been kept on file by the Boston Fire Underwriters Union since March, 1888, and each year since then has shown a vast improvement over the previous year as to quality of wire, insulation, finish and power to withstand abrasion. The samples of wire submitted in the year 1888 showed a very uncertain quality, the insulation showing a resistance of from 1800 megohms to 3.3 megohms per mile upon being submerged in water and many of the samples showed no resistance whatever after having been in water five or six days with only 140 volts used in making In recent issues we gave a description of the electric car lighting system of the Lewis Electric Co., and of their windmill plant designed as a source of electrical energy; b both being operated in connection with storage batteries. In the one case we have a dynamo driven from the car axle and in the other by the windmill through gearing. The character of both these driving agents is identical in the variable nature of the speed to which the dynamo must necessarily be subjected and our readers will recall the fact that in those descriptions we stated that the inventor, Lieut. I. N. Lewis, U. S. A., had designed a very simple method for obtaining a constant potential at the battery terminals, without introducing any auxiliary regulating apparatus, which has heretofore so greatly retarded progress in this direction. We are now able to describe the method alluded to, which consists simply in a special method of winding the field magnets of the dynamo. In the ordinary method of compounding dynamos for constant potential where the driving speed is constant, the current in the series coil acts cumulatively with the shunt to maintain the strength of the field magnetism. To accomplish the maintenance of constant potential with varying speed, however, Lieut. Lewis simply reverses this order of things and connects the series coil differentially or reversely, so that its acts to demagnetize and weaken the field as the speed increases. The method will be readily understood by inspection of the accompanying diagram which shows the long shunt method of connection, the same principle of course holding true with the short shunt. The shunt coil is here shown at b and the regulating differential series coil at a. The results obtained in practice with this method of winding are quite remarkable. In some recent tests with speeds varying between 600 and 800 revolutions and with current varying from 1 to 35 amperes, the potential did not vary more than 1 volt from the normal 35 volts for which the machine was designed. With such a machine available the problem of electric car lighting and windmill. storage is in a fair way to find a speedy solution. ELECTRIC TRANSPORTATION DEPARTMENT. THE CHLORIDE ACCUMULATOR ON PARIS Some attempts at electric traction by accumulators have been made in these latter years in France as well as in other European countries but nearly every where this method of traction has been abandoned, principally on account of the failure of the system of accumulators employed. The Street Railway Company of Paris and the Department of the Seine once abandoned the system after a few months' use on its St. Denis lines. Now, however, it is no longer a question of mere experiment, but one of genuine industrial development. The installation of the St. Denis station has been made in view of the development of two lines, each about six miles in length. They both extend from the rond-point de Picardie at St. Denis, the one to the Madeleine, the other to the Opera. The first trials took place in February, 1892. Electric traction has The accumulators are of the chloride type, manufactured by the Société pour le Travail Electrique des Métaux, to the operation of which its distinguished director, M. Sarcia, has imparted a very remarkable impulse. The accumulators are placed under the seats of the car. There are one hundred and eight elements of eleven plates each contained in hard rubber boxes. The plates are seven and three-quarter inches by seven square and a quarter of an inch thick, and the weight of an element is thirty-eight and a half pounds. These one hundred and eight cells are divided into twelve groups of nine batteries each, contained in twelve wooden boxes, six on each side of the car, the batteries of each group being connected in series, and the two terminals attached to copper strips fastened to one of the partitions of the wooden box. To the wooden props of the car are attached brass springs connected to the motor circuits, with intermediate regulating switches. The introduction of the boxes into the car causes these been employed regularly on the portions of the two lines situated outside of the city walls since June 1st. Horse cars were entirely done away with on the Madeleine line October 1, and will shortly be abandoned on the Opera line. A third line, about three miles long, running from the mayoralty house of St. Ouen to Neuilly, will soon be operated by electric cars. The plan laid out for the constructors of the motors and accumulators was to substitute for the horse cars on the two lines above designated, self-propelling cars, with seats on the roof, having a carrying capacity of fifty passengers and two company employees. The lowest speed imposed, with full car, was seven and a half miles per hour, with the possibility of attaining a speed of ten miles an hour outside of Paris, and a minimum rate of three and three-quarter miles on the heaviest grades, which are about four per cent. Moreover, the company reserved the right of attaching another car to the electric cars. The daily mileage of each car was to be at least sixty-five miles, and the weight of the ac cumulators, including all accessories, was not to exceed 6,000 pounds. All these conditions have been fulfilled to the letter. The body of the car rests on rollers upon two trucks, each having one axle, and being held in place by a king bolt. These two trucks are bound together by a system of joints and springs, which allows the axles to converge on curves and restores them to parallelism on a straight track. A motor is attached to each axle by double-reduction gear wheels, the ratio between motor and axle being twelve to one. The gears are in an iron casing, the first pair completely immersed in oil. The motors are bi-polar, of the Manchester type, with Gramme armature, series wound. The brushes are four carbon blocks. Each motor will develop, with a speed of 1,350 revolutions per minute, a power of 10,000 watts, with a difference of potential of 200 volts. Under these conditions the efficiency between motor and axle is seventy-three per cent. The trucks and motors were supplied by the firm of Averly, of Lyon, and M. Lemoine's roller brake is used. springs to slide on the copper strips and the circuit through the constituent parts of the battery is thus automatically established. The batteries are charged on a platform made of joists, covered with tar, supported by brick piles and supplied with glass insulators. These platforms have brass contact springs like those in the cars. The batteries when placed on the platform for charging are connected in series. The station for accumulators has space for twenty-four sets of batteries, each one connected to a distributing switchboard by a special circuit, in which is an ammeter, a polarity indicator, a double-pole circuit breaker and a make and break switch. The transfer of the batteries between the charging tables and the cars is effected by means of small cars moving on tracks which run alongside of the platforms and the street car tracks. When a car returns to exchange its discharged battery for another, seven of these transfer cars are ranged on each side of the tracks, six carrying boxes of accumulators freshly charged and the seventh empty. The first box of batteries contained in the street car is slid on the empty transfer car by which it is carried to the place which it is to occupy on the charging platform. The first box of the new battery passes from its transfer car into the space in the street car thus left empty, and a second box of discharged battery is removed, and so on consecutively. The platform of the transfer car can be raised and lowered by a screw and fly wheel so that it can be brought to the level of the interior of the street car or of the charging platform. This is accomplished in five minutes or less. The charging current for the accumulators is furnished by three Desroziers dynamos. constructed by the firm of Bréguet, each run by a one hundred and twenty-five horse-power Corliss horizontal condensing engine. Two of these engines run at a speed of seventy-five revolutions, and the third at one hundred and sixty revolutions. This last runs its dynamo by means of a single belt, the other two by intermediate shafting. The engines are supplied by three semi-tubular boilers. This plant was installed by M. E. Garnier. Each dynamo, at a speed of 600 revolutions, develops a current of 230 ampers, with an electromotive force of 260 volts, and the sets of accumulators are charged in parallel, with a constant electromotive force of 260 volts. The duration of the charge is six hours for a battery which has furnished all its capacity of 230 ampere hours, or fifty-two horse-power hours. The yield in energy of the batteries is as high as seventy per cent. The batteries in service, with an electromotive force of upwards of 200 volts, give a discharge, which on grades reaches seventy amperes, or nearly two amperes per pound of element. The average output on the level is about thirty-five amperes, which increases to fifty-five amperes on grades of two and a half per cent. One charge of the batteries will run the car about forty miles on grooved rails and about seventy-five miles on ordinary T rails. In order to operate the car at the various speeds required in service the coupling of the cells of battery is changeable. In the car the batteries are divided into four parts, each of twenty-seven cells in series, which give, on closed circuit, about fifty volts. By means of a regulating switch, placed under the control of the driver, three couplings of batteries may be obtained of 50, 100, or 200 watts. The speed of the car is doubled in passing from one coupling to the other. The motors of the car are usually connected in series, but, by means of a switch, may be placed in parallel when greater speed or power is required. This second switch also reverses the direction of running of the car by reversing the current in the motor armatures, and by it also a motor may be cut out of service in case of damage by short circuiting on the series combination. A single motor is sufficient to run the car with a slightly reduced speed. The switch for altering the coupling of the sub-batteries consists of a cylinder of non-conducting material, carrying three sets of copper strips, corresponding to the three couplings or combinations of the batteries. These strips become connected when the cylinder is revolved on its axis between the metallic brushes, communicating with the sub-batteries. In passing from one position to another the current is broken before the strips are released from between the brushes, the break being made on special strips supplied with blocks of carbon, so arranged as to be easily replaced. The barrel is revolved by means of a lever. The switch or regulator which changes the couplings of the motors is composed of three commutators, operated by separate cranks, which are so interlocked that they cannot be operated except when the current is broken by the battery switch. The daily service on the Madeleine route (the only one at present entirely operated by electric cars), consists of one hundred and four trips, or fifty-two round trips. Seven cars are operated on this line, some making eight and others nine trips, about ninetytwo and one hundred and three miles; while horse cars make not much more than sixty miles. Each car is operated with two sets of batteries, making from four to six consecutive trips, forty-six to sixty-nine miles without recharge. The running time between terminals is fifty-five minutes, including stops. The weight of a full car is about 29,000 pounds, of which 5,700 pounds are for the batteries and their accessories and 7,700 pounds for the passengers. The mean tractive force is about twenty-six and a half pounds per ton. The average results of operation on the Madeleine line for October, November and December, 1892, per car mile are as follows: Ampere hours charged, 6.2; horse-power hours, generated, 2.2; coal consumed, 9.2 pounds; oil consumed, .015 pound. The averages for a whole year would be lower, as the average for the three months considered is relatively high in consequence of the heavy condition of the road due to mud, snow and ice. The road is built of T rails, weighing about fifty pounds to the yard, except in St. Denis and Paris, where the Broca grooved rail is used, weighing about ninety pounds to the yard. The service has been very regular and the receipts per car mile have increased to a marked degree, and the favor of the public has been instantly won by the new, comfortable cars lighted by electricity. Encouraged by the good results obtained, the street car company has determined to introduce storage battery traction on their other lines. On the new cars, which are to be built, a system of regulation is to be employed whereby, in stopping the cars and in running down grades, the motors will become generators, and a portion of the energy previously given out by the accumulators restored. Great credit is due to the manager and directors of the street railway company through whose efforts and perseverance storage battery traction has triumphed in Paris, and will, it is thought, be speedily adopted throughout France. CAPACITY OF RAILWAY MOTORS. BY I. d. Menill. THE usual traction formula or table gives the draw-bar pull required to keep a given load in motion either at a very slow speed or at some specified speed and with a specified coefficient of resistance. While these tables are applicable at all speeds to locomotives and other engines where the tractive power may be kept constant and the power consumed varies directly with the speed for any given tractive power, they are not at all applicable to electric motors in which the tractive power is constantly varying independently of any method of motor control, and in which the energy utilized in propelling the load may be, and often is, very different from the total energy consumed. To illustrate: A certain table gives .32 h. p. as the power required to propel 1 ton at a speed of 4 miles per hour, on a level, with a coefficient of resistance of 30; a 50 h. p. equipment should therefore be capable of propelling 156 tons at this speed without exceeding its rated h. p.; this might easily be true for a steam locomotive but is assuredly not for an electric motor which, if geared for a normal speed of 12 miles per hour, will reach its normal ampere capacity at 52 tons. The table is therefore unreliable and almost useless at all speeds and loads except those at which the motors will give their rated output. The reason for this discrepancy is found in the fact that the tractive power of the locomotive can be varied widely and for indefinitely long periods without undue strains on the working parts, while electrical and mechanical limitations practically compel a maximum tractive power in the motor not far above its normal capacity except for very short periods; this tractive power, aside from magnetic variations in the iron, is dependent upon the ampere capacity of the motor windings. and is practically the same for all speeds; therefore, as the coefficient of resistance in street railway work will not vary by any determinable amount for speeds up to 12 or 15 miles per hour, the maximum load that can be propelled at any speed will not exceed the maximum load that can be propelled at its rated speed so long as the normal tractive power is not exceeded; the speed will vary directly with the E. M. F. at the motor terminals. This indicates a simple method of ascertaining what is more important than the total horse power consumed in moving the load, viz., the proportion of the normal tractive power which must be excited to move any given load, the rated horse power and normal speed of the motor at the E. M. F. of the line being known. For, from the horse power and speed at which that horse power will be developed the pull at the periphery can be determined and this pull is independent of all variations in wheels, gears, speed reductions or armature diameters, and also holds true per horse power for any size of motor. If we know the ratio of tractive power exerted to normal tractive power we know pretty accurately how far the proper carry. ing capacity of the armature and field windings is being utilized or overloaded; the total horse-power consumed does not give the remotest indication of this important point. To determine this ratio the writer has used the following table which is presented with the hope that others may find it equally useful; it is based on the assumption that the rated horse-power of the motors can be applied at the periphery of the driving wheels at the rated speed without overheating fields or armatures. |