This watch was a full plate model with the train developing to the left from the center and illustrations No. 22 and 23 are given to show that, while the train follows the Swiss development, the spring follows the American method and develops to the right from the collet even though it is located to the left of the watch center. The principle remains the same as that illustrated by Figs. 9 and 11 and explained in Chapter VIII.
[69.]Example No. 7.
Waltham. No. 10504112. Open Face, Vanguard model, 23 Jewels.
Repairs made. Cleaned and new hole jewel.
First five position test showed a very erratic rate as per second column Fig. 24.
Investigation proved that the motion dropped off considerably after a few hours run and that the mainspring was too weak for this grade of watch. A proper mainspring was fitted which in turn corrected the motion, but the next test in positions proved that there was still a variation of eighteen seconds as per fourth column Fig. 24.
| No. ...10504112......... Make...Waltham......... | |||||||
|---|---|---|---|---|---|---|---|
| D U | 0 | 0 | - 2 | - 2 | - 1 | - 1 | P |
| D D | 0 | 0 | - 5 | - 3 | - 1 | 0 | |
| P U | +14 | +14 | -21 | -16 | - 4 | - 3 | |
| P R | + 4 | -10 | -19 | + 2 | - 5 | - 1 | |
| P L | +16 | +12 | -25 | - 6 | - 3 | + 2 | |
| 24 | 18 | 5 | |||||
The balance and spring were removed and considerable poise trouble was discovered. The trouble was at different points of the balance and no one location seemed to be heavy at all times. The balance pivots were carefully gauged with a metric micrometer and found to be out of round, or to be exact, more oval in form than cylindrical. A new staff with round pivots was fitted, after which the balance was easily poised and the next test showed a variation of five seconds as per sixth column Fig. 24. The total time required for making the examination and alterations was about one hour.
[70.]Example No. 8.
Vacheron and Constantin. No. 272,854, Open Face, 21 Jewels.