See that the pivot holes are of the right size, and the end-shakes correct; if not, alter as may be necessary. Try, in the same manner, the centre-wheel depth with the third pinion, the third-wheel depth with the fourth pinion, and the fourth-wheel depth with the escape pinion, taking care to remember the pivot holes and end-shakes. Observe, also, that the centre wheel is free of its bed and the third wheel of the pillar plate.
In verge watches, it is very essential that the mainspring should be adjusted to the fusee, for the vertical escapement is so sensitive to variations of the motive force, that the time indicated would vary with the force that reached the escapement. In other escapements there is a kind of compensation in the action of the escapement which renders adjustment unnecessary. To adjust the mainspring, the barrel, fusee, and centre wheel are placed within the frame, and the top plate is pinned on. The chain is then attached to the fusee by the small hook, and to the barrel by the large hook, and wound up tight round the latter by turning the barrel arbor with a bench key. The ratchet is placed on the barrel arbor, and the spring is "set up" about half a turn - that is, the arbor is turned round about half a turn more than is required to pull the chain tight. The "adjusting-rod" (which is merely a weighted lever with sliding weight) is then secured to the winding square, and about one turn is given to the fusee. The weight is then moved along the rod, until it exactly counterbalances the force of the spring. The fusee is then turned till filled with the chain, and tested to see if the mainspring exerts the same power at the last turn as it did at the first.
If the last turn will pull over the weight quicker than the first, the spring is not set up enough. If, however, it shows less power at the last turn than at the first, then it is set up too much. When the correct adjustment is found, a slight mark is made upon the end of the top pivot of the barrel arbor, and a corresponding one on the name plate or top plate, as the case may be. Another item requiring attention is to see that the cannon pinion does not confine the shake of the centre wheel, and also that the cannon-pinion teeth are free of the third-wheel teeth.
Having completed the examination of the watch, with the exception of the eseapement - which for the present is assumed to be correct - it only remains to clean the different parts and put them together again. The greatest care must be taken to thoroughly clean each piece, and keep it clean until the movement is replaced in the case. Several methods are followed for giving the work a good appearance. Some workmen dip the various parts into pure benzine, others into spirits of wine or some other liquid, which renders the removal of grease and dirt easy; but equally good results will be obtained from the following plan : - Use a good soft watch-brush, occasionally rubbing it gently upon a piece of prepared chalk or burnt bone, holding the wheels, plates, and other parts in a piece of clean tissue paper, to prevent the perspiration from the skin soiling them. As each piece is cleaned, it must be placed under a "covering glass" (a wineglass broken at the stem being generally used for the purpose), to keep it free from dust until the movement is put together again. The chain does not require brushing, but simply wiping with a clean piece of chamois leather or tissue paper.
The "balance spring" (usually known as the hair spring) is best cleaned by laying it flat on the board paper and gently patting it with the brush; when very dirty or oily, the quickest way is to place it in some spirits of wine for a few minutes, and then pat with the brush.
The parts being ready for putting together, the first item to attend to is the oiling of the pivots which cannot be reached with the oiler after the movement is together. In the verge movement, these are the foot hole of the potence, the dovetail hole, follower hole, the pivots of the barrel arbor on which the barrel turns, and the jewel holes in the frame which have end-stones or cover-pieces in the lever.
The plan of putting together is as follows: - Take the potence, and, having oiled the foot and dovetail holes, screw it in its place upon the top plate, put in the escape wheel (called the "balance wheel" in the verge escapement only), push in the follower and oil its hole. Care must be taken to apply only a very minute quantity of oil - too much oil is as bad as none at all. See that the end-shake of the balance-wheel pinion is only just sufficient to ensure freedom, and that the wheel turns freely. Next take the pillar plate and arrange the wheels in their proper places in the following order: third wheel, centre wheel, fusee, barrel, and lastly the contrate, or fourth wheel. Put the top plate in position, and carefully guide the pivots into their respective holes, keeping the plate just tight down up n the pivots, but using no undue force. When all are in their right places, secure the top plate with the examining pins, and see that the train of wheels runs freely. In putting together, every piece must be held either in tissue paper or the tweezers, and no "finger marks" must appear on the plates or elsewhere.
Adjust the name plate, as well as the slide containing the index, or regulator, and secure them with the screws. Try all the end-shakes, and see that each piece has the necessary amount of freedom without excess. Attach the chain by the small round-ended hook to the fusee, and by the large pointed hook to the barrel, and wind it regularly round the latter till the chain is pulled tight. Then set up the spring in accordance with the adjustment previously made. The pivot holes of the frame may now be sparingly oiled, also the hole in the cock which receives the top pivot of the verge. Proceed to put the verge in, exercising great care, for owing to its very fragile construction it is easily broken. Always see that the bottom pivot of the verge is fairly in the foot hole before attempting to put the cock on in place.
The arbor that carries the balance, whether it is called a verge, a cylinder, or a staff, has to be placed in a certain arbitrary position relative to the next piece which moves it, in order to ensure the correct action of the escapement. When it occupies this position, it is said to be "in beat"; when otherwise, "out of beat." This position is necessarily determined by the connection of the balance spring with the plate, and one of the functions of the balance spring is to continually restore the balance, and with it the arbor, to its neutral position. The operation of finding the exact place for the balance spring to be secured in the stud by means of a pin is called "setting the watch in beat"; a practical method of setting the verge watch in beat is as follows: - Put the end of the hair spring through the stud, so as to bring the verge approximately to its correct position, and pin it moderately tight, taking the precaution to have the spring within the curb pins and quite flat. Put on the cock, and turn in the screw.
Hold the movement in the left hand, and with the thumb of the right hand slowly and carefully press forward the contrate wheel, allowing each escape of a tooth to be quite distinct; observe how much the balance is drawn to the right in order to allow the escape to take place, and how much to the left. If it is found that the distances are equal, the watch is in beat; if unequal, the cock must be removed, the pin withdrawn a little, and the balance spring moved in the direction necessary to make the "draw" equal.
This being correct, the pin must be pressed in tight, the balance spring set quite flat, working equally between the curb pins, and finally the cock screwed firmly on. The chain can now be wound upon the fusee, guiding it carefully into the grooves by means of a pointed peg - the stopwork having been tested at the time of adjusting the mainspring. Put on the cannon pinion, minute wheel, and hour wheel, and pin on the dial. The movement will now be finished and ready for the case.