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Show M ' vi SWIFTER. THAU" HAGKE3. Speed of Two and a Half Miles Per Minute to be Made. . (New York Tribune.) fc An experiment in electric traction "which will command world-wide atten- j 1 tion is soon to be made on a short mili- tary railway extending southward frm I I Berlin. The feature of the project - which has thus far received the most i I notice, and which, from a popular point : j of view, is probably the most inter-i inter-i i t-sting, is the speea which it is pro- f posed to develop. This is at the ."ate of between 125 and 135 miles an hour, I I or between two and two and a quarter miles a minute. The road is only f eighteen and one-half miles in length, f "' and hence the trip should be made in IV eight or nine minutes. If, however, jj such a speed can be maintained for I . that interval, it can be kept up for an I hour. All new questions of air reslst-R reslst-R ance and road and car equipment ought f j to be disposed of in a tenth of that f j time. f " It has been repeatedly pointed out " , that much higher speeds than are now I attained on steam railways would be practicable if curves and grade cross- ; Ings were done away with. It may also prove necessary to modify the A form of the car more or less, the bet- ter to withstand a blast greatly sur- i . passing the average hurricane in vio- J v lence. The Berlin-Zossen track meets the first of these requirements already, f And partial provision has been made for the second by rounding the fronts ; and sloping the roofs of the cars near 5 the ends. Whether a more elaborate ? taper will eventually prove desirable; is yet to be determined. 1 The coming trial will involve com- j paratively new and important problems prob-lems in electrical engineering. In the first place, the alternating current will be used instead of the direct current, j which is in practically universal ser- ! vice in traction work. This innovation ; has been introduced on a few roads in Switzerland and a line in Italy which i skirts Lake Como, with apparent suc- ; Xf cess, although a speed of more than j forty-five miles an hour has not been ' , recorded. In the next place, the feasi- bility of taking off the current when running at the rate of 120 miles an hour ' , has been doubted. Again, the "tri- "V phase" system of alternating currents calls for a more complicated arrangement arrange-ment of conductors than the direct ' current. The Lake Como line uses two j f overhead wires and employs the rails as a substitute for the third. The j BerlinVZossen road will have three overhead, -wires, with three poles at j each end of the car to make the con- I I tacts. In several other particulars also the apparatus will be original in design, de-sign, and until its practical efficiency Is demonstrated absolute confidence s cannot be felt in regard to the result. ; A larger degree of uncertainty exists I in the minds of experts as to the sat- isfactory working of the alternating I current for traction purposes than the j possibility of making 120 or even 140 " miles an hour. The former question is I one over which wide differences of j opinion prevail. Further experiment s , and discussion are needed, therefore, j to bring out the truth, i - The electricians long ago found that k it is much more convenient to transmit . i electricity for long distances when it . is in the form of an alternating cur- .i rent, because the voltage can be readily read-ily raised, and because it takes less copper to conduct at a high voltage ' ' than at a low one. Consequently this style of current is universally employed !j on transmission lines. Then, if at the I terminus a trolley road is to be oper- ' ated, not only is The voltage brought down to the desired level, but another j process is gone through with. The al-t al-t ternatlng current is "converted"' into a i direct one. It has been argued that !f I this last step could be avoided less ap-I ap-I paratus would be needed, and that a i - certain small waste of energy would j " . be prevented. Such reasoning is met ! with the assertion that there are losses in other ways which more than com- ' pensate for the gain. And so the j . economy of th new scheme, as well as ! the efficiency of the mechanism. Is yet I . . in doubt. Finally, when these oues-I oues-I tions have been cleared up, it will still be necessary to inquire into the ex- pedieney of using a system which will - not allow cars to be run over connect- ing roads where the direct current is employed. |