Revolving steel and iron forts.
--We clip the following from the Philadelphia Sunday Transcript of April 20:‘ There has been on exhibition for several days in the Treasury building, Washington, one of the most remarkable works of inventive genius which has ever come under our observation. It is nineteen years since Timbey's revolving steel or iron batteries were invented, models made, and all the details laid before our Government; and, it is eight years since they were communicated to the French Government. The present model was finished in December last, and is of itself a beautiful and demonstrative exhibition of the manner that harbor and other defensive positions must, before long be fortified, and thus rendered impassible to any foreign foe. The vertical sides are pierced for sixty guns of any desirable calibre, and range of shot or shell arranged in three tiers, and presenting the guns to the object singly; that is, but one "port" in line of sight at a time. The whole superstructure, which is to be above ground, is made to turn on its vertical axis by a concealed steam power, say three hundred horse engine; which engine is also to force hot or cold air through the casements for the benefit of the garrison. The guns occupy galleries of equal height — in three tiers. When the structure is put in motion, the whole number of guns will bear on the object every two minutes, if it only revolves at the rate of one hundred and fifty feet in a minute, or one- fourth speed of a man at an ordinary walk. The officer in command takes his position in the top of the iron castle, where, under the upper dome, there is a narrow opening through which the light enters, and permits him to see out through a telescope, or theodolite, which instrument is fixed in position on a stand and platform, which platform moves by the hand of the commander — turning a slight wheel — on its vertical exist, independent of the moving of the castle by the motion of the steam-engine. The result is, that the operator, having determined by the micrometer of the theodolite the distance of the object to be hit outside the castle, telegraphs to each gunner the angle of elevation or depression, to act the guns, and all being loaded, he sets the castle in revolution by signal to the engineer; and when each gun falls into the same vertical line that held by the theodolite bearing on the object, or target, the gun is at that instant fired by an electric spark which ignites the priming of each gun in turn, as it bears on the object. In a word, there will be a continuous stream of the heaviest metal discharged from the largest guns that can be made or used anywhere, at any object within range, and at any point of the compass, without the slightest possible danger or inconvenience to the persons who are to occupy the inside of the walls and dome of this mighty engine of war.
’
