Repairs made. New balance staff, hole jewel, cap jewel, glass, and cleaned.

The first test after making the repairs showed a variation of twelve seconds as per second column Fig. 25.

It will be observed that the rates in the horizontal positions are on the fast side and those in the vertical positions are on the slow side. In this instance the hairspring developed to the left from the collet similar to the illustration shown in Fig. 10, page 45.

Fig. 25
No. ...272854........... Make...V. & C. ........
D U+ 2+ 2- 4- 4P
D D+ 5+ 3- 8- 4
P U- 1- 6-14- 6
P R- 8- 7-21- 7
P L-17- 9-15- 4
12 3

Investigation found the escapement, regulator pins and pinning point satisfactory; the motion was one and one-fourth turn in the vertical positions when fully wound and only a trifle less when partially let down. In the flat positions, however, the motion was very little better than in the vertical, which indicated either pivot or end stone trouble as under normal conditions the flat motion would be about one-fourth turn greater than that of the vertical.

Inspection of the end stones proved that they were satisfactory but the ends of the balance pivots were found to be somewhat flat and not perfectly polished.

The ends of the pivots were slightly rounded and highly polished, the jewels and end stones cleaned and reoiled and the balance replaced, after which the motion in the flat positions was one and one-half turn with the mainspring fully wound and only slightly less when partially let down.

The motion in the vertical positions was also slightly improved and the next test in position showed a variation of three seconds as per fourth column Fig. 25.

Time required for making the above alteration was about one-half hour.

In the study of this example it should be clearly understood that when the ends of balance pivots are flat, burred or not well polished, or when the end stones are dry or dirty the motion in the horizontal positions will be shorter than normal and this will always cause the rate to be faster than it should be. Acceleration of the motion in such instances by means of refinishing the pivot ends or by cleaning and reoiling the jewels and end stones will always produce a slower rate through causing a longer arc of motion.