In other cases, specially designed electric motor-cars have been constructed with a view to obtain a higher speed for passenger trains than is at present attained with the locomotives, and the trials made have proved that these cars could reach a high speed, but so far only with limited loads. Experiments are still going on with larger and improved machines, from which it is expected to obtain both high speed and much increased hauling power. It is more than probable that amongst the earliest practical applications of electric motive-power on existing railways will be its introduction as an auxiliary on the steep gradients of some of the mountain railways abroad. In many of these regions there are millions of gallons of water running to waste down the ravines, a portion of which could be utilized in working powerful generating plant, to drive strong electric motor-cars for assisting the ordinary locomotives up the steep inclines. In such localities, with free water-power, the cost of the electricity would be at a minimum, while the cost of the ordinary locomotive would be at a maximum. In whatever form the electric motor-car may be designed, we are brought face to face with the old axiom, that there must be a certain amount of weight to obtain a certain amount of adhesion; but there will be one important point in favour of the motor-car, that whereas in the ordinary locomotive the weight for traction can only be distributed over a few working wheels, the electric arrangement may distribute it over a much greater number, and so diminish the insistent weight of each wheel upon the rails. There would also be the 357 saving of the dead weight of the tender, the fuel, water, and other minor accessories, as well as the advantage that the active power would be applied in a rotary form instead of reciprocating. There are important interests at stake in the perfecting of this new system of haulage, and day by day new developments are being made to add to its efficiency and reduce its cost. Existing railways will, however, naturally require some very convincing proof of the all-round superiority of electricity before adopting that power generally in place of their present locomotives. The latter, with their corresponding workshops and appliances, represent so large an amount of invested capital, as to demand most thorough trials and investigation of the new power before they are superseded; nevertheless, if further experience proves that electrical power is better and cheaper than the ordinary steam locomotives, then the change will undoubtedly be made.