320 
COLUMBA MIGRATORIA. 
have travelled between 300 and 400 miles in six hours, 
making 1 their speed, at an average, about one mile W * 
minute ; and this would enable one of these birds, if s# 
inclined, to visit the European continent, as swallo" 9 
undoubtedly are able to do, in a couple of days. 
individual of this species was shot, while perched on j 1 
wall near a pigeon-house at West Hall, Monym*® ’ 
Fifeshire, on the 31st December, 182.3.* This '"a-- 
Explanation of the Flight of Eirds . - — Were each muscle 
of 
o uum l/c no n/uumunuu* * , • 1 ■ — ’■ * , - 
respect. Thus, for example, in the lowering of the wings, durtf# 
flight, the resistance or contraction of the middle pectoral muse 
and their congeners is absolutely necessary, since without it t 
wings would fall by their own weight, and the action of * ^ 
great pectoral muscles would be useless. Besides, in the depress] 1 ’^ 
of the wings, the fixed point of the middle pectoral muscles, whi 6 ‘ 
is at the humerus, where their respective tendon is attach 6 ’ 
retiring, it must necessarily be that the sudden contraction ol th 6 ‘ 
muscles contributes to the ascent of the trunk, until the moo* 6 
when the humeri are arrested by the cessation of the action of * 
great pectoral muscles. ^ £ 
It is easy to conceive why the projector muscles of the tru ^ 
and the depressors of the wings are stronger thau the levators* ^ 
is because the former have to make the trunk perform a kiflh 
leap, and by this means lower the wings, notwithstanding J 
resistance of the latter ; and these, not being able to prevent t 
humeri from falling, take their fixed point in them, and draw 
trunk upwards, thus seconding the action of the great 
muscles, and participating of the kind of projection of the trow* 
upwards and forwards. e 
Thus, to enable the bird to rise in the air, and direct itself tn 6 , 
all the muscles of flight must contract in the following 
The clavicle and scapula, being fixed by the trapezius, the 
boideus, the upper part of the longissimus dorsi, the costo-scapu 
and the clavicularis brevis, and the wing being in part unfob ^ 
carried forwards, and raised by the action of the pectoralis met 1 • 
infra-clavicularis internu9, the levatores humeri, the coraco- ^ 
chialis and extensors of the anterior membrane of the wing> 
bird then springs into the air, in accomplishing the extension 0 
wings. At the same time, the great pectoral muscles, the ^ 
cipal ones of the wings,’ and whose fixed point is as the humeri*^ 
the insertion of their respective tendon, suddenly contract , _ ^ 
on account of the resistance which the air opposes to the mou° 
1 
