draw the line a a. At some convenientposition on this line is established the point a, which representsthe center of the escape wheel. In this drawing it is not impor-tant that the entire escape wheel be shown, inasmuch as we havereally to do with but a little over sixty degrees of the periphery… … thirty degrees from the brass degree arc, and through the pointsthus established are drawn the radial lines a b and a d. The point on the arc n where it intersects with the line b istermed the point b. At the intersection of the radial line a d isis established the point d. We take ten and one-half…
Clocks and watches
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![An illustration from [Graphophone patents] (1878)](https://img.insideoutlibrary.com/img/200/ia-graphophonepaten07unit-337-227.webp)
