CHAPTER VII

[Theory and Practice]

[26.] Theory of Frictional Errors and the Isochronal

Hairspring.

[27.] How Theory Works Out in Practice and what

Isochronism Consists of.

[28.] Common Causes of Extreme Isochronal Variation.

CHAPTER VIII

[Relative Pinning Points of the Hairspring]

[29.] Original Springing of Watches.