The mines from which most minerals, such as sulphuret of lead (galena) or of copper, are drawn, belong to the second class, or those whose shafts “cut” the vein of mineral at a very acute angle. When the existence of the required mineral and its “dip” or inclination is ascertained, a shaft is sunk so as to cut its upper surface, and then carried through it, cross-cuts being formed on to the vein, and “levels” or galleries right and left in the direction of the vein. From these levels “winzes” or small shafts are cut at intervals from one level to that below it, thus leaving square portions of the mineral vein to be explored, which is done by digging away the roof or upper part, so that the rubbish and ore falls down, when it is sorted and carried away. SHIPS. Illustration: BUILDING SLIPS. Illustration: FIG. 1. (‡ KEEL CONSTRUCTION.) Illustration: FIG. 2. (‡ TREENAIL.) The first part of a ship “laid down” is the “keel;” this is the projection which runs along the whole length and forms the lowest part of the ship. The ship is built in what is called the “building slip,” which slopes towards the water; in this “slip” a row of oaken blocks are placed at a few feet apart, and about three feet high, on which the keel is laid; these blocks are for the purpose of allowing the workmen to cross from side to side below the keel and to form a foundation for the ship to rest on. In fig. 1, A is this arrangement of blocks, C the keel, at the hinder part of which is the “dead wood,” or the timbers filling up the space between the keel and the curved bottom of the ship, which is more curved than the keel, and very much so towards the “stern” or hindermost part. Across the keel are laid the “floor-timbers” or “ribs,” B, which are curved timbers laid at right angles to the keel and passing outwards and upwards in the exact curve which the sides of the ship are to assume; these are too curved and too long to be of one piece, others, therefore, are added, and joined end to end with the first by wooden bolts or “dowels;” these curved timbers are cut to a pattern, chalked on the floor of the “mould-loft.” The ribs as they cross the keel are bound to it by a piece of strong timber running along inside of or above them, but parallel to, and exactly over it, which is called the “keelson,” and is bolted to the keel through the centre of each lower piece of the ribs or floor-timbers; it is shown at D, fig. 1. In large ships there are three of these keelsons, running side by side, and forming a strong support to the masts, which rest upon them. At each end of the keel a bar of timber rises, the hindermost being called the “stern-post,” and that in front the “stem-post” (marked E and F in fig. 1). Across the ribs on the outside and parallel to the keel, are laid the “planks,” which are boards of oak of from two to six inches thick, laid close together and touching at their edges;