naval architecture has been put in requisition by the Emperor of Russia and the Sultan of Turkey. The steam machines invented by our countrymen to drive piles, load vessels, and excavate roads, are most ingenious and useful. The use of steam, as a locomotive power, upon the water and the land, is admirably adapted to our mighty rivers and extended territory. From Washington to the mouth of the Oregon is but one half,[3] and to the mouth of the Del Norte but one fourth, of the distance of the railroads already constructed here; and to the latter point, at the rate of motion (thirty miles an hour) now in daily use abroad, the trip would be performed in two days, and to the former in four days. Thus, steam, if we measure distance by the time in which it is traversed, renders our whole Union, with its most extended limits, smaller than was the State of New York ten years since. Steam cars have been moved, as an experiment, both here and abroad, many hundred miles, at the rate of sixty miles an hour; but what will be the highest velocity ultimately attained in common use, either upon the water or the land, is a most important problem, as yet entirely unsolved. Our respected citizens, Morey and Drake, have endeavored to substitute the force of explosion of gaseous compounds for steam. The first was the pioneer, and the second has shown that the problem is still worth pursuing to solution. An energetic Western mechanic made a bold but unsuccessful effort to put in operation an engine acting by the expansion of air by heat; and a similar most ingenious attempt was made by Mr. Walter Byrnes, of Concordia, Louisiana; as also to substitute compressed air, and air compressed and expanded, as a locomotive power. All attempts to use air as a motive power, except the balloon, the sail vessel, the air gun, and the windmill, have thus far failed; but what inventive genius may yet accomplish in this respect, remains yet undetermined. There is, it is true, a mile or more of pneumatic railway used between Dublin and Kingstown. An air pump, driven by steam, exhausts the air from a cylinder in which a piston moves; this cylinder is laid the whole length of the road, and the piston is connected to a car above, so that, as the piston moves forward on the exhaustion of the air in front of it, the car is also carried forward. The original idea of this pneumatic railway was derived from the contrivance of an American, quite unknown to fame, who, as his sign expressed it, showed to visitors a new mode of carrying the mail,[4] more simple, and quite as valuable, practically, as this atmospheric railway. The submerged propeller of Ericsson, and the submerged paddle wheel, the rival experiments of our two distinguished naval officers, Stockton and Hunter, are now candidates for public favor; and the Princeton on the ocean, as she moves in noiseless majesty, at a speed never before attained at sea, seems to attest the