The earliest railway rates were tolls charged for the use of the permanent way and were based on mileage, or on a combination of mileage and tonnage. The next stage came with the adoption of steam locomotion. The Stockton and Darlington Railway, for instance, was empowered by Parliament to charge a ‘locomotive toll’ in addition to the other charges when a trader made use of the company’s engines. Then when it became the rule for companies to provide wagons and incidental services, they were authorized to make a charge for ‘conveyance’ Parliament at first only stipulated that these charges should be ‘reasonable’ and no attempt was made to fix maximum rates since it was thought that the competition of outside carriers would keep rates down. But when this competition began to dwindle, Parliament fixed maximum charges for the various locomotive and conveyance tolls. This was generally done when Private Acts were passed to incorporate new companies or to extend the powers of old companies. Three separate charges were thus authorized by Parliament, viz. (1) road tolls, (2) locomotive tolls, and (3) conveyance tolls.