Why we take sixty-four
degrees for the angle _A b g_ will be explained later on, when we are
discussing the angular motion of the cylinder. By dividing the eleventh
degree from the point _b_ on the arc _a a_ into thirds and taking two of
them, we establish the point _y_ and draw the radial line _A y'_. Where
this line _A y'_ intersects the line _b g_ we name the point _n_, and in
it is located the point of the escape-wheel tooth. That portion of the
line _b g_ which lies between the points _b_ and _n_ represents the
measure of the inner diameter of the cylinder, and also the length of
the chord of the arc which rounds the impulse face of the tooth. We
divide the space _b n_ into two equal portions and establish the point
_e_, which locates the position of the center of the cylinder. From _A_
as a center and through the point _e_ we sweep the arc _e' e'_, and it
is on this line that the points establishing the center of the cylinder
will in every instance be located. From _A_ as a center, through the
point _n_ we sweep the arc _k_, and on this line we locate the points of
the escape-wheel teeth.
Pages:
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228