Rack Striking Work.
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 the rack is thrown back a distance corresponding to the width of two of its teeth. This requires two revolutions of the gathering pallet to return it to its place; and these two revolutions of the pallet and the wheel which carries it govern the two blows on the bell which signify the hour. At three o'clock the third step of the snail will be presented to the hammer-tail, and so on.
On the next page is an illustration of the back part of a French Clock, as seen upon opening the door of the case. At the right hand side will be observed the count-wheel A, fitting tightly upon a prolonged square arbor of the second wheel in the train, and having twelve openings of unequal length around its outer edge, 1, 2, &c. Just above the wheel towards the right will also be seen the 'Dog,' or 'Detent,' F, which falls into these notches, and is a part of the locking similar to that which is represented at the stud and the pin H. So soon as the stud is lifted the pin becomes disengaged, the wheel-work revolves, and the count-wheel being firmly fixed to the prolonged arbor of one of those wheels, advances with it in the direction indicated by the arrow, the detent resting upon the plain part of the locking-wheel. When the required number of hours have struck, the notch approaches the detent, the gravity of which allows it to fall therein.
Back of French Clock.
In connection with this detent is also another projecting piece, which is carried inside the frame, and when it falls presents a broad surface to a pin fixed in the rim of one of the wheels. Thus the motion of the wheel-work is stayed until this piece is again lifted by the going parts from the pin, and held in that position by the outer rim of the locking-wheel A, until again the next notch is presented to the detent. When it falls, the stud is carried with it, against which the pin becomes engaged. The number of strokes depends on the distance which the count-wheel has to revolve before being stopped by the detent F. The chief objection to the locking-plate being used for striking, arises from the fact that, if ever the clock is allowed to run down, or if the clock gets otherwise stopped, it strikes wrong afterwards, until it has been properly re-set to the hour.
Clocks are made of all manner of shapes, patterns, and sizes, for all manner of places, positions, and persons.
Bracket Clocks, which are intended to occupy but a small space, say on a staircase, or lobby, or landing, are sometimes made with extreme finish, care, and elegance, sometimes are simply plain and devoid of embellishment. They are constructed with or without striking work.