All methods of transport must be judged by their cost of operation and the revenue they produce, and the comparison, therefore, of the cost of ton-miles provides a useful but not the only basis from which conclusions can be drawn as to the efficiency and utility of such services. Vehicle, train, ship, or air miles and their cost must also be considered as well as ton-miles, and above all the factors of speed and the completeness of the service from the point of view of the user must be taken into account.

We have seen during the last few years attempts made to bolster up certain methods of transport on the ground that they are beneficial as a whole to the community, to special trades, or to the welfare of particular places or classes. But sooner or later the practice of subsidising any kind of transport out of taxes or rates, or out of the proceeds of other allied concerns, will have to be recognised as unsound, though there are exceptional cases where one service is naturally complementary to another kind of service, and in the end the methods of transport that will survive will be those that can stand upon their own bases.