pounds, and when discharging at the lower rate of 22.34 amperes the available useful energy was 72.313 foot pounds, or nearly 2.2 electrical horse power per pound of active matter.  But this active substance has to be supported, and the strength or weight of the support has to be made sufficiently great to give the plate a definite strength and durability.  The support of the plates inclusive of the terminals above referred to weighs more than the active material, which consists of peroxide of lead and spongy lead; so that the plates of one cell weigh actually 26.5 pounds.  Add to this the weight of the receptacle and acid, and you get a total of about 41 pounds per cell when in working order.  Seventy of these cells will propel an ordinary street car for four hours and a half, while consuming the stored energy at the rate of 30 amperes, or over 5.6 electrical horse power.  The whole set of seventy cells weighs 2,870 lb., which is barely one-fifth of the entire weight of the car when it carries forty adult passengers.  Therefore the energy wasted in propelling the accumulator along with a ear does not amount to more than 20 per cent. of the total power, and this we can easily afford to lose so long as animal power is our only competitor.  From numerous and exhaustive tests with accumulators on cars in this country and abroad, I have come to the conclusion that the motive power for hauling a full-sized street car for fifteen hours a day does not exceed $1.75, and this includes fuel, water, oil, attendance, and repairs to engine, boiler, and dynamo.  We have thus an immense margin left between the cost of electric traction and horse traction, and the last objection, that relating to the depreciation of the battery plates, can be most liberally met, and yet leave ample profits over the old method of propulsion by means of animals.

The advantages of storage battery street cars for city traffic are self-evident, so that I need not trouble you with further details in this respect, but I would beg those who take an interest in the progress of the electric locomotive to give this subject all the consideration it deserves, and I would assure them that the system which I have advocated in this brief but very incomplete sketch is worthy of an extended trial, and ready for the purposes set forth.  There is no reason why those connected with electric lighting interests in the various cities and towns should not give the matter their special attention, as they are the best informed on electrical engineering and already have a local control of the supply of current needed for charging.

In the car which we use in Philadelphia there are actually 80 cells, because there are considerable gradients to go over.  Each cell weighs 40 pounds and the average horse power of each battery is six.  Sometimes we only use two horse power and sometimes, going up grades of 5 per cent., we use as much as 12 horse power, but the average rate is 6 electrical horse power.  With reference to the weight of passengers on the cars, we have never carried more than 50 passengers on that car, because it is impossible to put more than 50 men into it.  There are seats for 24, and the rest have to stand on the platforms or in the aisle.