Few words are necessary to explain the present revision. When the work originally appeared, it excited great interest among artisans, and at once took the foremost rank among works of the kind. By its intrinsic merit, it has ever since maintained this position, although, latterly, many professedly new and original works have been issued, with the avowed object of taking its place. They have failed to obtain foothold; and the limited sale which some few have been so fortunate as to secure, must be attributed to the extensive and valuable contributions levied on this work of Mr. Nicholson's. Indeed, it has been for many years the great source of supply to pseudo authors, who, having mutilated what they took to avoid recognition, represented their alterations as new and superior designs. Some have, to a limited extent, succeeded; but not among those who were acquainted with this.