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THE pioneer work of WILBUR and ORVILLE WRIGHT in producing the first aeroplane to fly nearly fifty years ago has been splendidly perpetuated in the wonderful series of WILBUR WRIGHT MEMORIAL LECTURES (of which the fortieth will be read this year) in England, and, in America, WRIGHT BROTHERS LECTURES. For the benefit, particularly, of our home readers we have long made a practice of publishing the latter series in full, with the kind permission and co‐operation of the INSTITUTE OF THE AERONAUTICAL SCIENCES, when they have been, as happens in alternate years, written by a British author, and consequently the fifteenth lecture— by DR P. B. WALKER of Farnborough—appears in this issue.