e impulse to the roller.

[Illustration: Fig. 26.]

[Illustration: Fig. 28.]

The impulse is transmitted closer to the line of centers than could be
done with any ruby pin. If the pin _i_ were wider the impulse would be
transmitted still closer to the line of centers, but the intersection of
it with the roller would be less. It is very delicate as it is,
therefore from a practical standpoint it ought to be made thin but
consistent with solidity. If the pin is anyway large, it should be
flattened on the sides, otherwise the friction would be similar to that
of the round ruby pin. It would also be preferable (on account of the
pin _i_ being very easily bent) to make the impulse piece narrow but of
such a length that it could be screwed to the fork, the same as the dart
in the double roller. The impulse radius is also the radius of the
roller, because the impulse is transmitted to the roller itself; for
this reason the latter is smaller in this action than in the ordinary
one having the same angles; also a shorter lever is in contact with a
longer one in the unlocking than in ordinary action of the same angles;
but for all this the pins _u u_ should be pitched close to the edge of
the roller, as the angular connection of the balance with the escapement
would be increased during the unlocking action. This escapement being
very delicate requires a 12deg. pallet angle and a proportion between
impulse and pallet angles of not less than 3 to 1, which would mean an
impulse angle of 36deg.; this, together with the first rate workmanship
required are two of the reasons why this action is not often met with.

George Savage, of London, England, invented this action. He was a
watchmaker who, in the early part of this century, did much to perfect
the lever escapement by good work and nice proportion, besides inventing
the two pin variety. He spent the early part of his life in Clerkenwell,
but in his old days emigrated to Canada, and founded a flourishing
retail business in Montreal, where he died. Some of George Savage's
descendants are still engaged at the trade in Canada at the present day.

The correct delineation of the lever escapement is a very important
matter. We illustrate one which is so delineated that it can be
practically produced. We have not noticed a draft of the lever
escapement, especially with equidistant pallets and club teeth, which
would act correctly in a watch.

We have been aggressive in our work and ha