View source for Cayley, 1843, Retrospect of the progress of aërial navigation and demonstration of the principles by which it must be governed

Cayley examines the question of heavier-than-air flight in light of the publicity around Henson's recent invention. He argues that propulsion is the key, that the steam engine is too heavy, and that the success of this type of aircraft depends on the future development of a lighter "first mover". He expresses some optimism about an engine using "common atmospheric air expanded by heat" through the combustion of coke.

{{Publication
|Original title=Retrospect of the progress of aërial navigation and demonstration of the principles by which it must be governed
|Simple title=Retrospect of the progress of aërial navigation and demonstration of the principles by which it must be governed
|Authors=George Cayley
|Date=1843
|Countries=GB
|Languages=en
|Keywords=Patent GB-1842-9478; airplane; heavier-than-air; propulsion; glider; stability; hot air; motor; internal combustion
|Journal=Mech. Mag. Mus. Reg. Journ. Gaz.
|Related to aircraft=1
|Page count=3
}}
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=== Sources ===
* [[Brockett 1910]], page [https://archive.org/details/bibliographyaer02brocgoog/page/181 181], entry 2615: Cayley. Retrospect of the progress of aërial navigation and demonstration of the principles by which it must be governed. Mech. Mag. Mus. Reg. Journ. Gaz., Vol. 38, No. 1025 (April 1843), London, pp. 263-265. (2615
* [https://babel.hathitrust.org/cgi/pt?id=nyp.33433062611946&view=1up&seq=275&skin=2021 Scan] at HathiTrust