_C. Electricity._--Of electric cars there are many patterns, but at present they are not commercially so practical as the other two types. The great drawbacks to electrically-driven cars are the weight of the accumulators (which often scale nearly as much as all the rest of the vehicle), and the difficulty of getting them recharged when exhausted. We might add to these the rapidity with which the accumulators become worn out, and the consequent expense of renewal. T. A. Edison is reported at work on an accumulator which will surpass all hitherto constructed, having a much longer life, and weighing very much less, power for power. The longest continuous run ever made with electricity, 187 miles at Chicago, compares badly with the feat of a petrol car which on November 23, 1900, travelled a thousand miles on the Crystal Palace track in 48 hours 24 minutes, without a single stop. Successful attempts have been made by MM. Pieper and Jenatsky to combine the petrol and electric systems, by an arrangement which instead of wasting power in the cylinders when less speed is required, throws into action electric dynamos to store up energy, convertible, when needed, into motive power by reversing the dynamo into a motor. But the simple electric car will not be a universal favourite until either accumulators are so light that a very large store of electricity can be carried without inconvenient addition of weight, or until charging stations are erected all over the country at distances of fifty miles or so apart. Whether steam will eventually get the upper hand of the petrol engine is at present uncertain. The steam car has the advantage over the gas-engine car in ease of starting, the delicate regulation of power, facility of reversing, absence of vibration, noise and smell, and freedom from complicated gears. On the other hand the petrol car has no boiler to get out of order or burst, no troublesome gauges requiring constant attention, and there is small difficulty about a supply of fuel. Petrol sufficient to give motive power for hundreds of miles can be carried if need be; and as long as there is petrol on board the car is ready for work at a moment’s notice. Judging by the number of the various types of vehicles actually at work we should say that while steam is best for heavy traction, the gas-engine is most often employed on pleasure cars. [Illustration: _By kind permission of The Liquid Air Co._ _This graceful little motor-car is driven by Liquid Air. It makes absolutely no smell or noise._] _D. Liquid Air_ will also have to be reckoned with as a motive power. At present it is only on its probation; but the writer has good authority for stating that before these words appear in print there will be on the roads a car driven by liquid air, and able to turn off eighty miles in the hour.