It is well known that we can discharge the storage battery ad libitum at the rate of 2 amperes or 200 amperes.  I can get out of a storage battery almost any horse power I like for a short space of time.  I have not the least objection to the direct system.  But when you come to run twenty or thirty or fifty cars on one line, you will require very large conductors or dangerously high electromotive force.  The overhead system is applicable to its own particular purposes.  Where there are only five or ten, or even twenty, cars running on one line, and that line runs through a suburb or a part of a city where there are not many houses, that system is to be preferred.  The objection to the overhead system is not so much the want of beauty, but the want of practicability.  You have to put your posts very high indeed, so as to let great wagon loads of hay and all sorts of things pass underneath.  Most of the trouble comes in winter, and when it is snowing hard a great many difficulties arise.  As regards the loss, suppose that the resistance of the overhead lines is one ohm.  To draw one car it will take an average of 20 amperes, and the only loss will be 20 multiplied by 20, that is, 400 watts through line resistance.  But if there are ten cars on that line, you get 40,000 watts loss of energy, unless you increase the conductor in proportion to the number of cars.  If you do that, you get an enormous conductor, and have a sort of elevated railroad instead of a telegraph wire, as most people imagine an overhead conductor to be.

The current required to run a street car is about thirty amperes, and an electromotive force of about 180 volts.  If cars are run in connection with an incandescent light station, we can arrange our apparatus so that we can use an E.M.F. say of 110 volts, and then we can put in a smaller number of cells with a larger capacity that will give a corresponding horse power.  We can charge such larger cells with 50 or 60 amperes instead of thirty.

In regard to arc lighting machinery, the arc lighting dynamo should not be used to charge the accumulators.  They can be used, but they require such constant attention as to make them impracticable.  We can only use shunt-wound dynamos conveniently for that purpose.

In regard to using two motors on a car, there are several advantages in it.  I use two motors on all my cars in Europe, and always have done so from the beginning.  One of the advantages is that in case of an accident to one motor the other will bring the car home; secondly, with two motors we can vary the speed without changing the E.M.F. of the battery.  If I want very much power, I put two motors in parallel, getting four times the power that I do with one machine, and an intermediate power of two motors.

There is another advantage of having two motors, and that is that we can use two driving axles instead of one, and we can go up grades with almost double the facility that way, because the adhesion would be double.  These are the main advantages arising from the use of two or more motors.