. 
262 THE STRUCTURE AND LIFE OF BIRDS cuHap. 
and we should expect that unless some new factor 
should come in and upset the calculation, the areas 
would vary as the weight of the winged animal, 
whether bird or insect. That this is not the rule is 
shown by the following examples. 
Wing area per kilogram. 
Dragon-fly De jek «++ 44,032 Sq. inches. 
Swallow sick es w -1,544$ 45 
Vulture ... 395 ‘ive he 260 35 
Australian Crane iis si 139 3 
Thus the Australian Crane has in proportion to its 
weight only a little more than half the wing area of a 
Vulture, rather less than ~, of that of the Swallow 
and not quite 5}, of that of a Dragon-fly !? 
How are we to account for these facts? Before 
1 These figures are those of M. de Lucy, quoted by Professor 
Pettigrew, Anzual Locomotion; also by Professor Marey, 
Animal Mechanism, p. 222. I have not referred to M. de 
Lucy’s work, but the quotations agree. 
2 The following figures from L. P. Mouillard’s L’Empzre de 
Zaiy are interesting. They give in grammes the weight sup- 
ported by one square metre of surface, the whole undersurface of 
thé body as well as that of the wings being included. The 
small birds, as a rule, have far more surface for their weight, 
though the cock Kestrel heads the list and is an exception 
difficult to account for. Most startling is the small amount of 
surface that the Goose, Turkey, and Duck have to support 
them. 
Grammes supported by Grammes supported by 
1 sq. metre of surface, 1 sq. metre of surface. 
Kestrel (cock) we 1,968 Golden Plover ves 3,565 
House Sparrow 2,066 ‘Kestrel (hen) ... ve 38773 
Swift .. sesh we 2,073 Bustard oe w. 6,410 
Turtle Dove ... vee 2,133 Goose ... ee « 8,333 
Kite... sh . 2,226 Turkey... fe ss 9,345 
Starling a vee 2,932 Duck (Anas Clypeata) 
Raven ... zie - 3,012 » hen... ss 9,750 
Stork ... si we 3,536 » drake ... ws FT,050 
