In order, therefore, to protect the public against scientific bubbles we must impress upon both men and women the fact that an education in science is desirable, and is becoming more important as the world grows older; but until a scientific education becomes more general, it is important that there should be some scientific oracle of Delphos, and I can not think of any better than a well-managed scientific journal, the editors of which will seek for the best information on scientific questions which interest the financial world. When it is known that such a journal admits to its pages nothing that is sensational, when it is realized that the best specialists contribute to it, surely it will become a saving help in times of trouble. WHAT MAKES THE TROLLEY CAR GO. BY WILLIAM BAXTER, JR., C. E. NOTE.--The illustrations of railway generator and switchboard were made from photographs kindly furnished by the Westinghouse Electric and Manufacturing Company. For the photographs of the electric truck and car controller we are indebted to the courtesy of the General Electric Company. II. If the successful operation of a street-railway car by mechanical power depended wholly upon the ability to produce a motor of sufficient capacity to do the work, the problem would be an easy one to solve, and would have been solved long before the advent of the electric motor. Mere ability to furnish the necessary power, however, is not enough to meet the requirements. As already shown, the mechanism must be light, strong, compact, simple, and so well protected that it can not be injured except under abnormal conditions. In addition, speed-controlling devices must be provided whereby the velocity may be changed at will and in the shortest possible time, and with as nearly absolute precision as possible. This controlling mechanism must also be so arranged that the direction of motion may be varied with the greatest certainty and as rapidly as may at any time be required. The way in which these results are accomplished in an electrically operated car can be understood from Figs. 18 and 19, which are line drawings, in a simplified form, of an ordinary trolley car. Fig. 18 is an elevation showing the outline of the car body and the wheels in broken lines, while the motors and the wires through which the current is conveyed thereto are drawn in solid lines. Fig. 19 is a plan in which the outline of the car floor and the platforms is represented in broken lines, the solid lines being the motors and connecting wires.