s 
BEAUTIFUL BIRDS. 
ber from four to six or seven, are white, and are depo- 
sited in a bed of moss, at the further extremity of 
the hole. 
It may be thought unnecessary to enter at any 
len^rth into the habits and character of the Swallows 
{Hirundiniclce) , so familiar are they to every one from 
their being so constantly on the wing, such confiding, 
friendly visitors to our houses, and so strikingly 
active in their motions ; but their powers of flight 
are so extraordinary, and their mode of capturing 
insects so different to that of any other bird, that we 
cannot pass by the consideration of their structure 
and economy. These birds are observed during sum- 
mer, from morning dawn till twilight closes upon the 
departing day, flying through the air with the greatest 
rapidity ; skimming the surface of water, or gliding 
swiftly on motionless wing; turning and doubling, 
and darting like an arrow from a bow, with so much 
ease that but little exertion appears to be made by 
any of their limbs. It is evident, however, that they 
have to support themselves in the am as well as to 
make progress through it — that muscles must be in 
action; and it is surprising that they so seldom 
appear to need repose. They are for ever on the 
wing. The Swifts, which get their common name 
from the rapidity of their flight, are generally sixteen 
or eighteen hours on the wing every day, at that time 
of the year when they have their broods. During 
these hours it has been computed that they cannot, 
on the average, move over less space than a thousand 
or twelve hundred miles. The rapidity of their flight 
must require constant exertion, which cannot be kept 
