that too without materially increasing the expense. [Illustration] The application of steam-engines to the _propelling_ of _carriages_ on the public road, has hitherto been considered as a refinement in mechanics, rather to be wished for than a matter of reasonable expectation. The _locomotive_ engine was first employed for this purpose by Messrs. Trevithick and Vivian, in 1802; and it found a ready introduction to the mining districts where rail-roads are general. In some cases, five, six, and even ten waggons laden with coal are dragged up an inclined plane by means of these vehicles; and of course impelled by a high pressure engine, from the utter impossibility of carrying condensing water in a moveable vehicle. An engine of four horses' power, employed by Mr. Blenkinsop, impelled a carriage lightly loaded on a rail-road at the rate of ten miles an hour, and when connected with thirty coal waggons, each weighing more than three tons, its average rate was about one-third of that pace. When the locomotive engine was first tried, it was found difficult to produce a sufficient degree of re-action between the wheels and the tract road; so that the wheels turned round without propelling the vehicle. This inconvenience was, however, obviated by Mr. Blenkinsop, who, when he adopted the locomotive engine, took up the common rails, on one side of the whole length of the road, and replaced them by a series of racks, or rails, furnished with large teeth. The impelling wheel of the engine was made to act in these teeth, so that it continued to work in a rack which insured a sufficient degree of re-action. From the great weight of an ordinary _locomotive engine_ as well as the construction of its impelling wheel, it must be evident that the employment of this species of prime mover on the public roads would be in the highest degree destructive; and as such that its use will for some years to come be partially confined to the mining districts, in which the greatest facilities are offered for its general adoption. Indeed, we find in one neighbourhood alone, and within a space of less than thirty square miles, more than twenty miles of road admirably adapted for this species of conveyance; and it is a well known fact, that there are many situations in which iron rail-roads might be advantageously employed, in which it would be quite impossible to open a navigable canal. In illustration of the above fact, it may be proper to state, that a company, with a large capital, is now forming for the express purpose of facilitating the conveyance of goods by locomotive engines. The mode of applying the steam-engine to the purposes of navigation is equally simple with its employment in our manufactures. It is generally supposed that the _steam-boat_ is of very recent invention; on the contrary, however, the possibility of employing steam as a prime mover in the propelling of vessels was suggested as far back as the reign of Charles I.