The reader will
please bear in mind that we do not give these proportions as imperative,
because we propose to give the fullest evidence into the reader's hands
and enable him to judge for himself, as we do not believe in laying down
imperious laws that the reader must accept on our assertion as being
correct. Our idea is rather to furnish the proper facts and put him in a
situation to know for himself.
The reader is urged to make the drawings for himself on a large scale,
say, an escape wheel 10" pitch diameter. Such drawings will enable him
to realize small errors which have been tolerated too much in drawings
of this kind. The drawings, as they appear in the cut, are one-fourth
the size recommended, and many of the lines fail to show points we
desire to call attention to. As for instance, the pallet center at _B_
is tangential to the pitch circle _a_ from the point of tooth contact at
_f_. To establish this point we draw the radial lines _A c_ and _A d_
from the escape-wheel center _A_, as shown, by laying off thirty degrees
on each side of the intersection of the vertical line _i_ (passing
through the centers _A B_) with the arc _a_, and then laying off two and
a half degrees on _a_ and establishing the point _f_, and through _f_
from the center _A_ draw the radial line _A f'_.
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