320 
COLUMB A MIGRATORIA. 
have travelled between 300 and 400 miles in six hours, 
making- their speed, at an average, about one mile in a 
minute ; and this would enable one of these birds, if so 
inclined, to visit the European continent, as swallows 
undoubtedly are able to do, in a couple of days. An 
individual of this species was shot, while perched on a 
wall near a pigeon-house at West Hall, Monymeal, 
Fifeshire, on the 31st December, 1825.* This vast 
* Explanation of the Flight of Birds . — Were each muscle of 
flight to contract separately, it would only put in motion the most 
mobile of the parts of the body to which it is especially attached, 
but there would be no locomotion. This assertion is true in every* 
respect. Thus, for example, in the lowering of the wings, during 
flight, the resistance or contraction of the middle pectoral muscles 
and their congeners is absolutely necessary, since without it the 
wings would fall by their own weight, and the action of the 
great pectoral muscles would be useless. Besides, in the depression 
of the wings, the fixed point of the middle pectoral muscles, which 
is at the humerus, where their respective tendon is attached, 
retiring, it must necessarily be that the sudden contraction of these 
muscles contributes to the ascent of the trunk, until the moment 
when the humeri are arrested by the cessation of the action of the 
great pectoral muscles. 
It is easy to conceive why the projector muscles of the trunk 
and the depressors of the wings are stronger than the levators. It 
is because the former have to make the trunk perform a kind of 
leap, and by this means lower the wings, notwithstanding the 
resistance of the latter ; and these, not being able to prevent the 
humeri from falling, take their fixed point in them, and draw the 
trunk upwards, thus seconding the action of the great pectoral 
muscles, and participating of the kind of projection of the trunk 
upwards and forwards. 
Thus, to enable the bird to rise in the air, and direct itself there, 
all the muscles of flight must contract in the following order : 
The clavicle and scapula, being fixed by the trapezius, the rhom- 
boideus, the upper part of the longissimus dorsi, the costo-scapularis 
and the clavicularis brevis, and the wing being in part unfolded, 
carried forwards, and raised by the action of the pectoralis medius, 
infra-clavicularis inter nus, the levatores humeri, the coraco-bra- 
chialis and extensors of the anterior membrane of the wing, the 
bird then springs into the air, in accomplishing the extension of its 
wings. At the same time, the great pectoral muscles, the prin- 
cipal ones of the wings, and whose fixed point is as the humeris at 
the insertion of their respective tendon, suddenly contract ; and, 
on account of the resistance which the air opposes to the motion of 
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