ere on the jackshaft.
A small sprocket on each end of the shaft carried a chain from the
larger sprockets clamped to the spokes of each rear wheel. The lower
surface of the flywheel had been machined so as to form a friction disc,
with a one-quarter inch depression 3 inches in diameter turned in the
center. The drum was positioned so that its upper surface was
one-quarter inch below the face of the flywheel. Hanging loosely around
the drum was an endless belt, one and one-half inches wide, first made
of rather soft rubber packing material. The belt lay on the drum surface
between the fingers of a shipper fork. While it lay under the 3-inch
depression in the center of the flywheel, the belt and the drum were at
rest, but when it was moved away from that depression the belt wedged
itself tightly between the drum and flywheel, the resulting friction
causing the drum to turn and setting the vehicle into motion. The
farther the belt was moved toward the outer edge of the wheel, the
faster the drum and the vehicle moved.

In September 1892, Charles, who had contracted with a Peoria, Illinois,
firm to have bicycle parts manufactured, decided to move to that city.
Departing on the 22d of September, he did not return to Springfield for
over two years, and thus was not able to participate in the completion
and testing of the carriage. At the time of his departure several units
on the carriage were incomplete. A carburetor had not been built, nor
had a satisfactory burner or belt-shifting device. Charles had
experimented with various shifting levers just before leaving
Springfield: however, as he reported later, he did not succeed in
designing a workable mechanism.[15] Frank Duryea, now left to finish the
work unassisted, continued the experiments with the belt shifter. He
finally worked out a fork mounted on a carriage that was supported by
two rods, each of which slid in two bearings. Although the short
distance between the two bearings caused the shifter carriage to bind
occasionally, the device was thought to be sufficient and was installed
just in front of the frame. Connected to a system of cables, arms, and
rods, possibly similar to the present cam-bar shifter, the shipper-fork
carriage was moved from side to side by raising or lowering the tiller.

[Illustration: FIGURE 16.--DRAWING of the carburetor used on both Duryea
engines, 1893-1894, showing sight feed on left and choke mechanism on
right. (Smithsonian photo 13455