the brushes b b is not required. To avoid the accumulation of water in the conduit the drain G is provided with outlets d, located at suitable points.
Although this system is the simplest that can be devised for use in streets or public highways its construction is very costly, so much so that it can only be used in cities where the traffic is so great as to require the running of cars on short headway; and, furthermore, it can not be operated with any degree of success except in municipalities where there is a good sewage system. During the summer months it is liable to be more or less impaired by heavy showers, but the trouble in such cases is only temporary. In winter time snowstorms are liable to affect it in the same way, especially if, after a heavy fall, a warm wave comes along and produces a rapid thaw.
From the fact that no attempt whatever is made to protect the conductors, one would naturally suppose that every time there is a rain the road would be compelled to shut down; for, as the slot through which the plow travels is open, water can enter the conduit with the greatest freedom, and, in trickling down the sides, would be caught to some extent upon the brackets c c, and thus make its way over to the channel bars a a, and thereby destroy the insulation. Practice, however, shows that this action does not take place, at least not so often as to produce any serious trouble. The roads that are operated by electricity in New York, and also the lines of the Capital Traction Company, of Washington, D. C, employ this system, and they have been in operation a sufficient length of time to fully demonstrate that the difficulties actually developed by the action of the elements are not of a formidable character. On one occasion the Sixth Avenue road, in New York, was compelled to stop its cars for a short time just after a severe snowstorm, but the failure was not due to impairment of the insulation, according to the statements of the officials of the company, but to the fact that the melted snow froze upon the track and caused the wheels to slip around without sending the car ahead. The fact that other roads in New York, belonging to the same company, are being equipped with the system, is proof that, upon the whole, its practical operation is regarded as satisfactory; but it is very evident that it is not the final solution of the problem. A system to be a decided success must cost very little more than the ordinary overhead trolley, and its construction must be such that it will not easily get out of order. If it is not inexpensive it will not come into use except in places where the authorities will not permit the overhead wires. A surface or underground system ought to be more durable than the overhead, as the wires are not
