placed on it.  After this operation the spring is complete and ready to be placed on the shaft.  The use of the springs is said to be beyond estimate.  They may be employed to operate passenger elevators, the springs being wound by a hand crank.  It is understood that the French Government has applied for them for running small yachts for harbor service.  Among the advantages claimed for this motor are its cheapness in first cost and in operating expenses.  It is estimated that an engine of twenty-five horse power will be required at the station to wind the springs.  If there be one at each end of the line, the cost for fuel, engineer, and interest will not exceed $100 per week.  This will answer for fifty or any additional number of cars.  The company claims that by using twelve springs, each 150 feet in length, an ordinary street car can be driven about twenty miles.—­Phil.  Inquirer.

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CASTING CHILLED CAR WHEELS.

We show herewith the method employed by the Baltimore Car Wheel Company in casting chilled wheels to prevent tread defects.  The ordinary mode of pouring from the ladle into the hub part of the mould, and then letting the metal overpour down the brackets to the chill, produces cold shot, seams, etc.  In the arrangement here shown the hub core, A, has a concave top, B, and the core seat, C, is convex, its center part being lower than the perimeter of the top of the core.  Figs. 3, 4, show the core, A, in the side elevation and in plain.  Fig. 2 is a core point forming a space to connect the receiving chamber, E, above, with the mould by passageways, D D, formed in the side of the top of the core.  The combined area of these passageways being less than that of the conduit, F, from the receiving chamber, the metal is skimmed of impurities, and the latter are retained in the receiving chamber, E. The entering metal flows first to the lower hub part at H H, thence by the sprue-ways, G G, to the lower rim part at J J, being again skimmed at the mouth of the sprue-ways.  Thus the rim fills as rapidly as the hub, and the metal is of a uniform and high temperature when it reaches the chill.

[Illustration:  CASTING OF CAR WHEELS.]

In the wheels made by this firm, every alternate rib is connected with the rim, and runs off to nothing near the hub; the intermediate ribs are attached to the hub, and diminish in width toward the rim.—­Jour.  Railway App.

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ELECTRICITY AND PRESTIDIGITATION.

The wonderful ease with which electricity adapts itself to the production of mechanical, calorific, and luminious effects at a distance, long ago gave rise to the idea of applying it to certain curious and amusing effects that simple minds willingly style supernatural, because of their powerlessness to find a satisfactory explanation of them.