CHAPTER VII. 

 THE MACHINERY OF FLIGHT. 



THE BREASTBONE AND THE CONNECTED BONES MUSCLES AND 



QUALITY OF MUSCLE THE SCAFFOLDING OF THE WING 



PNEUMATIC BONES STDTFNESS OF WING EXPANSE OF BONE 



THE SPREADING OF THE WING STRUCTURE OF A FLIGHT- 

 FEATHER — MOULTING — LEGS. 



When we carve 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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