THE SWALLOW FAMILY 73 
like a large pipe cut in half, the long way. This 
half cylinder was laid on top of the brick cor- 
nice, and that made a little roof, you see. The 
whole length of that cornice was thus made into 
one long room, with a brick floor and terra-cotta 
roof, and an entrance at the end. That room 
must have had a dozen martin nests, for a flock 
was all the time sailing about in the air, above 
the roofs of the houses. 
As these birds eat only flying insects, they 
cannot stay with us when it is too cool for in- 
sects to fly abroad. So they leave us very early. 
When the little ones are out of the nest and can 
fly well, swallows from all the country around 
collect in great flocks, and go to some swamp, 
or lonely place where people do not go much. 
There the young ones are taught and exercised 
every day in flying. And some day we shall go 
out and find them all gone, not a swallow to be 
seen. They have started for their winter home, 
which is far south, in tropical countries, where 
insects never fail; but it is a comfort to think 
that next summer we shall have them back with 
us again. 
The swallows I have mentioned, barn swallow, 
eave swallow, and purple martin, are found all 
over our country. 
Let me tell you a story that shows the purple 
