The development of the mono‐sleeve valve for aeroengines.** The author recently presented a paper on this subject to the society of automotive engineers, u.s.a., entitled “the single sleeve as a valve mechanism for the aircraft engine”—see s.a.e. journal, september, 1938, p. 349. certain passages and illustrations included in this paper are taken from the s.a.e. paper, for which acknowledgement is made to the society of automotive engineers.