Langley Memoir on Mechanical Flight, Parts I and II, Volume 27 Number 3, Publication 1948, 1911Note 21 — Chapter V · ON SUSTAINING SURFACESReading editionSee “Internal Work of the Wind”; also Revue de L’Aeronautique, 3e Livraison, 1893.◇Copy noteReturn to CHAPTER V ON SUSTAINING SURFACES