But, Mother, when you tell that story again, you must not say little
throats, or any one will know who your travellers are quick enough;
but do please tell us more about them."

"Yes, Frank, you have caught me; these travellers are martins; and,
if you wish, I will tell you more about them. Mr. Wilson, whom I
have been reading to-day, calls them birds of passage."

"What does that mean, Mother"?"

"It means that they find it necessary for their support to pass from
one country to another when winter is coming on. At that time they
leave us.

Some people think that martins and swallows hide themselves from the
cold in holes in rocks and banks, or in hollow trees; but Wilson,
who spent many years in watching the habits of birds, and learning
their history, thinks that these fly a great way off to a warmer
country as winter approaches, and that they return again in the
spring."

"But how can they find the way?" asked Frank.

"All that we know about that, Frank, is, that He who created the
martins has given to them the knowledge that guides them right. In
their long way through the pathless air, they never make a mistake.
Our great vessels and our skilful captains sometimes get lost in the
wide ocean; but these little birds always know the way, and arrive
with unerring certainty at their place of destination.