The butts, after being treated as above described, are frequently oiled lightly on the grain, and are taken into the drying-lofts, where they are hung on poles till about half dry. They are then laid on the floor in piles, and covered up till they heat or "sweat" a little, which facilitates the succeeding operation of "striking." This is performed by laying the butt over a horizontal "beam" or "horse," and scraping its surface with a triangular pin, shown at D in Fig. 25. This pin has an even, though tolerably sharp, edge, and is so used that it stretches and smooths out the grain, without breaking it; and at the same time it removes a portion of the white deposit called "bloom," which has been mentioned. Common goods are frequently struck by the machine introduced by Priestman, of Preston Brook, shown in Fig. 44; but the work is not very uniform, and the leather is much compressed and stretched. For offal, the machine is a very useful one, and perfectly satisfactory. [Illustration: Fig. 45.] [Illustration: Fig. 46.] Butts are now generally struck by the very ingenious machine of Wilson, whose name has also been mentioned in connection with the disintegrator, and which is shown in Fig. 45. The arms carry blunt brass or steel knives or sleekers, and work outwards from the centre, while the butt is carried backwards and forwards over the drum. Stones may be substituted for the sleekers, when it is required to remove the bloom. The machine requires a firm foundation, as its reciprocating motion causes considerable vibration. [Illustration: Fig. 47.] After a light oiling and a little further drying, the butt is laid on a flat "bed" of wood or zinc, and is rolled with a brass roller loaded with heavy weights. Various machines are also in use for this purpose. In Fig. 46, is shown Wilson's spring butt-roller, in which the pressure is produced by springs immediately above the roller, which works backward and forward over a flat table, beneath a fixed girder. In the later patterns of this machine the roller is automatically reversed by a mechanical finger before coming to the edge of the butt. Fig. 47 shows an adaptation of the American pendulum roller, which is specially suited for refinishing Singapore kip sides and the commoner class of goods, giving great firmness and a high gloss. Fig. 48 represents a machine in which the roller is fixed, and works over a brass drum; it is specially adapted for offal, and, when used for butts, is apt to make them "baggy." In this machine, the reversing motion is obtained by using two belts, one being crossed. [Illustration: Fig. 48.]