There are only two kinds of striking parts now in use, and these are characterized by the terms 'Rack' striking work, and 'Count-wheel,' or 'Locking-plate,' striking work. The Rack striking work (see next page) is the best and safest ever introduced, because with it the clock may be made to strike any number of times within the hour. A, the minute wheel revolving in the direction of the arrow, and driving the wheel B, which is of the same size, and has the same number of teeth. C, a pin fixed in the wheel B, and acting on the lever D, which has its centre of motion in the point E. L, the click, the lower point of which acts in the teeth K of the rack M. S, the rack-spring, which acts upon the lower end of the rack, or, as it is called, the rack-tail, and brings it in contact with the snail P. Q and R are the jumper and its spring, by which the snail P, fastened to the star-wheel O, is kept in its place. Y, the centre of motion of the rack, on which it acts freely. In the wheel A is fixed a pin U, which, as the wheel A rotates, gradually forces before it a tooth of the star-wheel O, which carries with it the snail P, until at last the second step of the snail is opposite the rack-tail. While this is going on, the wheel B, driven by the wheel A, is advancing in the opposite direction, and, by means of the pin C, is pushing before it the end of the lever D. It is obvious that the other end, F, of the lever will be gradually raised, and this will lift the lower point of the click L out of the teeth of the rack. The latter being now free will yield to the action of the spring S, which will force its lower end into contact with the second step of the snail, and throw back the head of the rack to a corresponding extent. By this action the striking train of wheels is released, and the two wheels, G and I, seen in the upper part of our cut, begin to rotate, but are stopped by H, a pin that is caught by a stud which projects from the end F of the lever. As the wheel B advances, the pin C gradually frees itself from the long arm of the lever D, which drops by its own weight into its original position, and frees the wheels G and I, which immediately commence once more to rotate. At the centre of the wheel I is fixed the gathering pallet, that, as it revolves with the wheel, gathers up one by one the teeth of the rack, which is prevented from falling back by the lower end of the click L, and thus gradually draws it forward until the last tooth is reached, when the end of the gathering pallet abuts on the end of the rack head, and the train of wheels is once more at rest. It is obvious that for every tooth of the rack which is gathered up, there is one revolution of the wheel I, and this communicates with the tail of the hammer, causing at each revolution a blow on the bell. There is, as will be at once seen, an important connection between the various parts. When the second step of the snail is presented to the rack-tail, the head of