Unpublished paper and letters, 'Project for a perpetual motion' by A B Author identified as ‘A B’ presents a plan for a perpetual motion machine consisting of a large ‘receiver’ into which air is pumped by a system of levers and pistons. The text is accompanied by two figures of the machine. Preceded by a letter from A B to the President of the Royal Society, and a letter from J G [John George] Children to A B. Subject: Physics 1831