Rotary valves for four-cycle spark ignition engines have long fascinated the author. He describes a very early example of a rotary valve and then follows with an outline of the various developments with this type of valve within his own company. While such a valve has yet to achieve production status, he demonstrates his conviction that ideas initially formed around the rotary valve are quite likely to lead to useful developments in other directions, and quotes sound examples of cases in which this has happened in his experience.
