to Jason R. Hopkins of two patents,[9] in both of which
half rights were assigned to William D. Colt. Patent 165831, relates to a
barrel arbor for watches. The arbor will be seen (fig. 4) to consist of
two parts, one telescoped within the other and the composite arbor
_B_-_C_ supported at each end by the frame of the watch. The patent text
limits itself to a bare description of the arbor. In the light of what we
have seen of the shortcomings of the original model, however, the patent
drawings tell that much more had been accomplished on the general design
of a more workable rotary watch.

A square on arbor _C_ at the back of the watch permits winding the main
spring, which attaches to the largest diameter of _C_, a ratchet or
winding click being supplied just under support _F_. The inner or front
part _B_ of the composite arbor projects from the front of the movement
and revolves at the speed of the barrel arbor, which speed is not
specified. Also, looking at the perspective view, we see that while the
chronometer escapement has been retained, the balance has been placed
eccentrically to make room for the center arbor. The balance now
describes an orbit around the center of revolution. No driving train is
shown, it being irrelevant to the patent, but there seems to be ample
room for two intermediate wheels and their pinions between the escape
wheel and the train cock boss, seen at the upper right in the perspective
view of figure 4. Adding one more wheel and pinion to the train would
have the effect of reducing the number of revolutions required of the
spring barrel. We have seen from examination of the patent model of the
Hopkins rotary that this was necessary not only to reduce the number of
turns of the main spring and barrel but also to reduce the force
transmitted to the escapement. There seems little reason from the
foregoing observations and considerations to doubt that these
modifications had been realized by the time of this patent. Again no dial
gearing is shown. If the need for special gearing existed at this time it
seems strange that it was not covered by patent as was done in the later
patent[10] assigned to William B. Fowle. The only way to avoid special
gearing would be to revolve the barrel and train each hour so that the
minute hand could travel with them as it travels with the center wheel in
conventional watches. Once this condition was set up, the usual dial
gearing would apply.

Companion patent 1