THE NIGHTJAR AND THE SWALLOW. 51 
erecting its nest beneath the shelter of our eaves, or 
in our chimneys, and thus occasionally introducing 
insects of a rather unpleasant character into our 
dwellings, it injures us in no way whatever, and is 
most assuredly a being to encourage which is not 
merely an advantage, but a manifest duty. 
From the swift and the martin, with which it is 
frequently confounded, the swallow may be at once 
distinguished by the great comparative size of its 
forked tail, which, as may be seen by the accom- 
panying illustration, rather exceeds the entire body in 
length. 
EQUALLING the swallow in the speed and strength 
of its flight, the Swift even surpasses that bird in point 
of agility, the quickness and certainty with which it 
alters its course reminding one more of the vagaries 
of a flash of lightning than of those of a mere 
denizen of air. Most remarkable, perhaps, is the 
infrequency with which the wings are moved, the 
bird shooting through the air and twisting and 
turning almost as though its progress were due to 
the mere power of its will, and not to the exercise of 
its physical powers. ‘The tail, of course, bears its 
share in the flight, acting as a rudder by which 
the course may be directed, and a close observer 
may notice that this organ is in almost incessant 
motion, now being spread and now folded, even 
while the wings themselves are held closely to the 
sides. 
From other members of the family the swift may 
