it was resolved to strip one machine that night, which was done, and a complete set of bobbins was out of the plant and in a car before daylight the next morning. Of course, "blue smoke" rolled about our heads the next day, but after the return of the bobbins from the factory and the machine was put into service again it was so satisfactory to the operators that the manager gracefully acknowledged that he had been beaten. In a selling office much "charity" and "missionary work" become necessary. For example: A customer reports that his motor is burnt out; an investigation shows, perhaps, that a fuse is blown or the power is off the circuit; another reports his motor is grounded, which means he had a static discharge coming from the belt. Recently a customer thought something was wrong because the voltage on a compound direct current generator increased when the load came on instead of decreasing. He had always been used to the voltage decreasing with the increase of load and any other condition he reasoned to be wrong. A party had a two-phase motor operated on a two-phase threewire system; it became necessary to take this motor down and reinstall it in another place, but in connecting up again the common wire was put in one side; of course the motor operated badly, and after much worry and many sleepless nights, the manufacturer was called upon for aid. A few minutes' work put him right and the man showed unmistakeable relief and joy. KILOWATT HOURS PER CAR MILE A subscriber on the Pacific coast writes as follows: "The November issue contains an article by Mr. Graham Bright, 'Tests of Interurban Single-phase Equipment.' On page 655 I find the following sentence: "The kilowatts (kw hours?) per car mile and watt hours per ton mile can be calculated from the average kilowatts which is obtained by integrating the line real kilowatt curves and dividing by the entire time of run including the stop.' "It is true that these quantities can be calculated in the manner indicated, but if so calculated they will not be cor rect. "Suppose that the total kilowatt hours of the run, including several stops, be determined by means of an integrating wattmeter. Disregarding instrumental errors, the kilowatt hours so determined will be precisely the same as those shown by integrating the kilowatt-time curves. The watt hours, no matter how determined, divided by the car miles and the ton miles, will give the watt hours per car mile and per ton mile. "It should be evident to Mr. Bright that car miles and ton miles are functions of distance, not in the least of time: and that if he integrates the curves as he states and divides by the entire time of the run, including the stop, his average kilowatts, with reference to distance, will be low in just the ratio that the time the car is actually in motion is to the total time of the run including the stops. "It should be evident also that he h only to make his runs short enough an his stops long enough, and calculate t watt hours per car mile and per ton m according to the method he gives, make these quantities as low as pleases." The original paragraph is obvious) in error in omitting the word hours an referring to "kilowatts per car mi instead of kilowatt hours per car mile. The contention that the length of st does not affect the power per car mile quite correct. It is certainly true th "the watt hours, no matter how & termined, divided by the car miles a the ton miles, will give the watt ho per car mile and ton mile." The cr determines the watt hours in one w the original author in another, i. e., the are to "be calculated from the avera kilowatts." To make the calculation kilowatt hours, (which involves time from the average kilowatts it is clear necessary to introduce the number hours. Thus, if during a day of to hours (during which a car may ha stopped many times for various inte vals) it is found that the “average k owatts" are 100, then the kilowatt hout are 1000 and the kilowatt hours per c mile are found by dividing 1000 by t total number of miles traveled. It obvious also that the method specif for finding the average kilowatts correct. If a single test run is all th is involved the critic's method is simp and satisfactory. If the test includ many runs, Mr. Bright's method sho be used. THE ELECTRIC JOURNAL VOL. III. FEBRUARY, 1906 NO. 2. Some Features of Heavy Electric Traction Electric locomotives were put into service by the Baltimore & Ohio Railroad Company in the Baltimore tunnel about ten years ago. This first important installation of electricity in steam railway service was popularly supposed to be the forerunner of a large and immediate general adoption of electricity by steam railroads. This innovation, however, was slow to come. In fact, over ten years have elapsed and this initial installation has not yet been duplicated. An official intimately connected with this work, observing the attractive cost per engine mile, had estimates made for electrical service over a mountain division. The cost of copper, however, ran into such an enormous sum that even a serious discussion of the matter was precluded. The cost of transmission conductors is a most important factor in the electrification of steam railways. It has prevented the economical adoption of the ordinary direct-current method of operation for heavy service. It is the real underlying factor in the impetus which the single-phase system is giving to heavy traction because it employes higher voltages which greatly reduce the cost of conductors. Operation under steam railway conditions is quite a different problem from the running of street railways or interurban roads. The most favorable condition for an ordinary electric railway plant is the operation of a large number of small units which thereby distribute the load over the system. In an interurban railway with many sub-stations, six or eight miles apart, it is desirable that some cars be at all times upon each section supplied by a sub-station, so that both sub-stations and the conductors from them may be in continuous service at a fair load. The operation of many small units at frequent intervals has thereby met the commercial requirements for street and interurban railways. In steam railway operation, however, the economical movement of traffic is in large volume, that is, by long and heavy trains. The important recent advances in steam railway operation have contributed to this end. The capacity of freight cars has been more than doubled; the strength and efficiency of the draft gear has been increased; locomotives have been developed to give greater tractive effort and greater power; with trains of greater length radical improvement in air brake appliance has been secured; rails have been made heavier and bridges have been rebuilt; grades have been reduced and curves have been eliminated; all for the purpose of handling the traffic by longer and heavier trains. The principal limits to this development are now found in the steam locomotive. The length of its rigid wheel base, the maximum weight on a pair of drivers and the steaming capacity cannot be materially increased. The electric locomotive operated from a high voltage trolley possesses certain fundamental features which adapt it to overcome these limitations. The high voltage trolley with sub-stations widely separated so reduces the cost of the transmission system that it is no longer imperative to keep the load upon the system in small distributed units. The multiple control system, by which a locomotive may be divisible into several separate parts which may be combined into one unit, in so far as the operation by a single motorman is concerned, overcomes the limitations of rigid wheel base and the weight on drivers of the steam locomotive. Several steam locomotives drawing one train are distinct individual elements under the control of different crews. The operation of several parts as one individual electric locomotive is as simple as the operation of a subway train in New York. in which six or eight motor cars are simultaneously controlled from a single operating handle. The horsepower which can be applied to the drawing of a train by locomotives is limited by the boiler capacity, but in the elec tric system it has no corresponding limit, as all trains receive their power from a large power plant. In the handling of a heavy freight train up a grade there is no reason why a train should not operate at twenty or thirty instead of ten or fifteen miles per hour, except for the problem of supplying sufficient power. The drawbar pull and the horsepower hours are practically the same for moving a given train a given distance at the higher speed. The time consumed, however, is only half as great. Instead of supplying one thousand horsepower to each of two trains running ten miles per hour an electric power house can supply two thousand horsepower to a single train at twenty miles per hour with equal facility, thereby reducing the number of trainhours for the handling of a given traffic. The handling of heavier trains or the operation at higher speeds will enable the traffic to be readily handled where there may at present be great congestion, which with steam locomotives could be relieved only by additional tracks. Incidentally many of the elements of delay in steam operation, such as taking water and coal, failures to steam, drawing fires and the time required for making engines ready for service will be obviated by electric operation. These are some of the elements which have not been fully appreciated. The adoption of electric operation when applied to any class of service, be it illumination or the operation of street cars, or trains, or machine tools, is wont not only to accomplish more satisfactorily what was done before but to lead to new methods. The introduction of the single-phase system has removed some formidable barriers to the adoption of electricity for railway service, and promises both economy and new methods of facilitating traffic. F. H. SHEPARD The Card The article elsewhere in this issue by Mr. Parsons on an improved system of indexing, emphasizes the great advance which has occurred with respect to classifying and systemizing reeords in recent years. When text books, reference books and technical journals were few, the man with a fair ly good memory could readily recall important articles, and he Index |