3673. Brecknell, H., Munro, E. M., and Rogers, M. I. Feb. 17. Electric railways on the overhead trolley system. Conductors.-Relates to a frog or point for trolley wires which, when the electric vehicle is shunted, automatically directs the trolley arm along a predetermined path. Fig. 1 is a plan of the under face of the frog. The steel piece or ramp b is screwed to the base of the frog, and made taper on the left half, so that a trolley wheel coming along the wire a can pass over it on to the conductor c. If the vehicle is shunted back, the wheel is compelled by this ramp to pass on to the wire d. In case the ramp becomes worn, it can be at once replaced.