CHAPTER VII. 
THE MACHINERY OF FLIGHT. 
THE BREASTBONE AND THE CONNECTED BONES—MUSCLES AND 
QUALITY OF MUSCLE—THE SCAFFOLDING OF THE WING— 
PNEUMATIC BONES—STIFFNESS OF WING—-EXPANSE OF BONE— 
THE SPREADING OF THE WING-—STRUCTURE OF A FLIGHT- 
FEATHER—MOULTING—LEGS. 
When wecarve a Partridge or a Grouse, since other 
questions seem at the time of more pressing interest, 
we seldom give a thought to the fact that we are 
slicing and disjointing what has been a most mar- 
vellous flying machine. Yet so it is. When we 
carve the breast, we first cut through the Great 
Pectoral, the powerful muscle that lowers the wing. 
Lying below it we find, easily distinguishable, a 
much smaller, lighter-coloured muscle—in the 
Grouse and its kin markedly lighter. This smaller 
muscle lies in the angle between the keel and the 
sternum (or breastbone) proper; its work is the 
lifting of the wing. 
The Breastbone and the Connected Bones. 
The framework, the bony skeleton, is wonderfully 
adapted to the purpose to which it is put. It is 
most important, to begin with, that there should 
be a wide expanse of bone from which the great 
flight muscles may spring. And so the area of the 
sternum is increased by the large projecting keel. 
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