39 This is the result arrived at by Helmholtz, Ueber ein Theorem geometrisch ûÊhnliche Bewegungen flû¥ssiger KûÑrper betreffend, nebst Anwendung auf das Problem Luftballons zu lenken, Monatsber. Akad. Berlin, 1873, pp. 501ã14. It was criticised and challenged (somewhat rashly) by K. Mû¥llenhof, Die GrûÑsse der FlugflûÊchen, etc., Pflû¥gerãs Archiv, XXXV, p. 407, XXXVI, p. 548, 1885.
40 Cf. also Chabrier, Vol des Insectes, Mûˋm. Mus. Hist. Nat. Paris, VIãVIII, 1820ã22.
41 Aerial Flight, vol. II (Aerodonetics), 1908, p. 150.
42 By Lanchester, op. cit. p. 131.
43 Cf. Lãempire de lãair; ornithologie appliquûˋe û lãaviation. 1881.
44 De Motu Animalium, I, prop. cciv, ed. 1685, p. 243.
45 Harlûˋ, On Atmospheric Pressure in past Geological Ages, Bull. Geol. Soc. Fr. XI, pp. 118ã121; or Cosmos, p. 30, July 8, 1911.
46 Introduction to Entomology, 1826, II, p. 190. K. and S., like many less learned authors, are fond of popular illustrations of the ãwonders of Nature,ã to the neglect of dynamical principles. They suggest, for instance, that if the white ant were as big as a man, its tunnels would be ãmagnificent cylinders of more than three hundred feet in diameterã; and that if a certain noisy Brazilian insect were as big as a man, its voice would be heard all the world over: ãso that Stentor becomes a mute when compared with these insects!ã It is an easy consequence of anthropomorphism, and hence a common charôÙacôÙterôÙisôÙtic of fairy-tales, to neglect the principle of dynamical, while dwelling on the aspect of geometrical, similarity.
47 I.e. the available energy of muscle, in ft.-lbs. per lb. of muscle, is the same for all animals: a postulate which requires considerable qualification when we are comparing very different kinds of muscle, such as the insectãs and the mammalãs.
48 Prop. clxxvii. Animalia minora et minus ponderosa majores saltus efficiunt respectu sui corporis, si caetera fuerint paria.