[71] “On the Physiology of Wings, being an Analysis of the Movements by which Flight is produced in the Insect, Bat, and Bird.”--Trans. Roy. Soc. of Edinburgh, vol. xxvi.
_The Wing area decreases as the Size and Weight of the Volant Animal increases._--While, as explained in the last section, no definite relation exists between the weight of a flying animal and the size of its flying surfaces, there being, as stated, heavy bodied and small-winged insects, bats, and birds, and the converse; and while, as I have shown by experiment, flight is possible within a wide range, the wings being, as a rule, in excess of what are required for the purposes of flight; still it appears, from the researches of M. de Lucy, that there is a general law, to the effect that the larger the volant animal the smaller by comparison are its flying surfaces. The existence of such a law is very encouraging as far as artificial flight is concerned, for it shows that the flying surfaces of a large, heavy, powerful flying machine will be comparatively small, and consequently comparatively compact and strong. This is a point of very considerable importance, as the object desiderated in a flying machine is elevating capacity.
M. de Lucy has tabulated his results, which I subjoin:[72]--
[72] “On the Flight of Birds, of Bats, and of Insects, in reference to the subject of Aërial Locomotion,” by M. de Lucy, Paris.
+------------------------------------------------------+ | INSECTS. | +------------------------------+-----------------------+ | | Referred to the | | | kilogramme | | NAMES. |= 2lbs. 8oz. 3dwt. 2gr.| | | Avoird. | | | = 2lbs. 3oz. 4·428dr. | +------------------------------+-----------------------+ | | sq. ft. in. | | | yds. | |Gnat, | 11 8 92 | |Dragon-fly (small), | 7 2 56 | |Coccinella (Lady-bird), | 5 13 87 | |Dragon-fly (common), | 5 2 89 | |Tipula, or Daddy-long-legs, | 3 5 11 | |Bee, | 1 2 74-1/2 | |Meat-fly, | 1 3 54-1/2 | |Drone (blue), | 1 2 20 | |Cockchafer, | 1 2 50 | |Lucanus} Stag beetle (female),| 1 1 39-1/2 | | cervus} Stag-beetle (male), | 0 8 33 | |Rhinoceros-beetle, | 0 6 122-1/2 | +------------------------------+-----------------------+ +------------------------------------------------------+ | BIRDS. | +------------------------------+-----------------------+ | | Referred | | NAMES. | to the | | | kilogramme. | +------------------------------+-----------------------+ | | sq. | | | yds. ft. in. | | Swallow, | 1 1 104-1/2 | | Sparrow, | 0 5 142-1/2 | | Turtle-dove, | 0 4 100-1/2 | | Pigeon, | 0 2 113 | | Stork, | 0 2 20 | | Vulture, | 0 1 116 | | Crane of Australia, | 0 0 139 | +------------------------------+-----------------------+