have already obtained the sanction of the Legislature to charge the monstrous Toll of 1s. 6d, per "horse-power," as if it were a national object to prevent the possibility of such Engines being used: Besides, they have supplied no standard of their own conception of horse-power. Engineers have differed very much in their estimates of this power, there is not, therefore, much probability that the opposite interests of a Steam Coach proprietor and Toll collector would lead to any agreement as to the meaning of the term. But suppose the Legislature were to settle this point, and to arrange that a certain length of stroke and diameter of cylinder should represent a certain power, we still fail to ascertain that which alone it is essential to know; viz, the actual efficiency of the Engine. Can we regulate the density of Steam at which an Engine of a given size should be worked? To be effectual, it would be also necessary to ascertain the quantity of water consumed, and even this check would be inadequate with an Engine on. Mr. Trevithick's principle. If the toll be left as at present on "horse power," it would be the obvious interest of the proprietor to work with the smallest nominal power, but to increase as much as possible the force of his Steam, thereby increasing the probability of explosion.
Some Trustees have placed the Toll upon the number of wheels. The Committee would object to this mode of charge, if only, because it interferes between the rival modes of Steam travelling, and gives a bounty in favour of that, in which the Engine is placed on the same Carriage with the passengers. The opposite plan of separating the Engine from the Carriage is that which probably the Public will prefer, until the safety of the mode of conveyance shall have been fully ascertained.
There is still a more serious objection to this mode of charge, it tends to discourage the use of separate Carriages; although it must be evident; that if a certain weight be carried, it will be much less injurious to the road when divided over eight wheels, than when carried on four only. On this point the Com-
