THE PLANING-MACHINE ROOM IN MESSRS FAWCETT AND CO.’S ENGINE FACTORY, LIVERPOOL.--In this room are valuable and elaborately contrived machines for the planing or levelling of large plates, or other pieces of iron or brass, so as to give them a smooth, true, and polished surface. The article or piece to be planed is securely fixed by screw-bolts, &c. to a horizontal iron table, perforated with holes for the insertion of the bolts from beneath it in any required point, to suit the size or form of the article. This table, when put in motion, travels backwards and forwards with its load on two iron rails, or parallel slides. Over the centre is perpendicularly fixed what is called the “planing tool,” an instrument made of steel, somewhat in the form of a hook, with the point so inclined as to present itself towards the surface of the metal to be planed, as it approaches it on the table, so as, when all is adjusted, to plough or plane it in narrow streaks or shavings as it passes under it. The extremity of the tool is about half an inch to three quarters in breadth, and being of a round form at the under side, and ground or bevelled on the upper, presents a sort of point. If a plate of iron is to be planed, the operation commences on the outer edge, and each movement backwards and forwards of the table places it in such a position under the tool, that another small parallel cut is made throughout its whole length. The tool, in ordinary machines of this kind, is fixed so that it cuts only in one direction, as the plate is drawn against its edge or point, which is raised to allow of the backward motion of the plate. A new patent has however been obtained for a great improvement in this respect by Mr Whitworth, of Manchester, and several of his machines are on Messrs Fawcett and Co.’s premises. In these, by a peculiarly beautiful contrivance, the cutting instrument, the moment the plate passes under it, “jumps” up a little in the box or case to which it is attached, and instantly “turns about” in the opposite direction, and commences cutting away, so that both backwards and forwards the operation goes on without loss of time. The workmen very quaintly and appropriately call this new planing tool “Jim Crow.” A workman attends to each of the machines; and when the piece to be cut is fixed with great exactness on the moving table by a spirit-level, he has nothing to do but to watch that it remain so, and that the machinery work evenly and correctly. Where a very smooth surface is required, the operation of planing is repeated, and two plates thus finished will be so truly level, that they will adhere together. It should be added, that so perfect are these machines, that in addition to planing horizontally, they may be so adjusted as to plane perpendicularly, or at any given angle. * * * * *