Note 4 — Front matter

During the summer, 1891, Charles found the bicycle business left him some spare time, and the gasoline-powered carriages he had read of earlier came constantly into his mind in these periods of idleness.[4] He and Frank studied several books on gasoline engines, among them one by an English writer (title and author now unknown);[5] this described the Otto 4-stroke cycle as now used. Some engineers, however, were concerned because this engine, on the completion of the exhaust stroke, had not entirely evacuated all of the products of combustion. The Atkinson engine, patented in 1887, was one of the attempts to solve this as well as several other problems, thus creating a more efficient cycle. This engine was designed so that the exhaust stroke carried the piston all the way to the head of the engine, while the compression stroke only moved the piston far enough to sufficiently compress the mixture. The unusual linkage necessary to create these unequal strokes in the Atkinson engine made it seem impractical for a carriage engine, where compactness was desired.