(_e_) To the plates of the English edition has been added one, (plate A) representing a high-pressure engine as constructed by the West Point Foundry in the state of New York. The principal parts will be readily distinguished from their resemblance to the analogous parts of a condensing engine. The condenser and air-pump of that engine, it will be observed, are suppressed. At _v x_ and _y z_ are forcing-pumps by which a supply of water is injected into the boiler at each motion of the engine. For the four-way cock, used in the English high-pressure engines, a slide valve at _r s_, is substituted, and is found to work to much greater advantage. It is set in motion by an eccentric, in a manner that will be more obvious from an inspection of the plate than from any description.--A. E. (_f_) A very safe and convenient boiler for a high-pressure engine has been invented in the United States by Mr. Babcock. The boiler consists of small tubes, into which water is flashed by a small forcing-pump at every stroke of the engine. The tubes are kept so hot in a furnace, as to generate steam of the required temperature, but not hot enough to cause any risk of the decomposition of the water. The strength of the apparatus is such, and the quantity of water exposed to heat at one time so small, as to leave hardly any risk of danger.--A. E. (83.) Two years after the date of the patent of this engine, its inventor constructed a machine of the same kind for the purpose of moving carriages on railroads; and applied it successfully, in the year 1804, on the railroad at Merthyr Tydvil, in South Wales. It was in principle the same as that already described. The cylinder however was in a horizontal position, the piston-rod working in the direction of the line of road: the extremity of the piston-rod, by means of a connecting rod, worked cranks placed on the axletree, on which were fixed two cogged wheels: these worked in others, by which their motion was communicated finally to cogged wheels fixed on the axle of the hind wheels of the carriage, by which this axle was kept in a state of revolution. The hind wheels being fixed on the axletree, and turning with it, were caused likewise to revolve; and so long as the weight of the carriage did not exceed that which the friction of the road was capable of propelling, the carriage would thus be moved forwards. On this axle was placed a fly-wheel to continue the rotatory motion at the termination of each stroke. The fore wheels are described as being capable of turning like the fore wheels of a carriage, so as to guide the vehicle. The projectors appear to have contemplated, in the first instance, the use of this carriage on turnpike roads; but that notion seems to have been abandoned, and its use was only adopted on the railroad before mentioned. On the occasion of its first trial, it drew after it as many carriages as contained 10 tons of iron a distance of nine miles; which stage it performed without any fresh supply of