[33] “A tax upon carriages in proportion to their weight, though a very equal tax when applied to the sole purpose of repairing the roads is a very unequal one when applied to any other purpose, or to supply the common exigencies of the State. When it is applied to the sole purpose above mentioned, each carriage is supposed to pay exactly for the wear and tear which that carriage occasions of the roads. But when it is applied to any other purpose, each carriage is supposed to pay for more than that wear and tear and contributes to the supply of some other exigency of the State. But as the turnpike toll raises the price of goods in proportion to their weight, and not to their value, it is chiefly paid by the consumers of coarse and bulky, not by those of precious and light, commodities. Whatever exigency of the State, therefore, this tax might be intended to supply, that exigency would be chiefly supplied at the expense of the poor, not of the rich; at the expense of those who are least able to supply it, not of those who are most able.”--(_Wealth of Nations._ Book 5 part 3.) In a few years, experience proved that the theories on which Parliament had proceeded were impracticable. In the first place, the notion that railways could be used by all comers in much the same way as canals or roads was found to be erroneous. Railway companies accordingly applied, in their special Acts, for powers not only to find locomotive power and wagons, but also to convey traffic as common carriers. In 1845, the Railways Clauses Act (s. 86) authorised every company to convey on their railway all such passengers and goods as might be offered to them for that purpose, and to make such reasonable charges in respect thereof as might be from time to time determined upon, not exceeding the tolls by the special Act authorised to be taken. The special Acts contained, as has been stated, imperfect classifications of merchandise, the maximum rates chargeable for conveyance, and powers to charge for loading, unloading, and other services incidental to the business of a carrier. About 1845 a second great change in the mode of charging for conveyance came to pass; and it is a circumstance worth noting that about that date a similar change took place, without concert, in France, Belgium and wherever railways existed. Up to that time railways had, as a rule, acted on the principle of equal mileage rates. This proved disadvantageous; it did not meet the requirements of trade; it was particularly unsatisfactory to distant traders; it prevented the opening up of new districts; and it needlessly limited the amount of traffic.