As soon as they entered the gates, Tommy escaped from Captain Osborn,
and ran away in his hurry to see the lions; but Captain Osborn caught
him again, and held him fast by the hand.

"Here is a pair of very strange birds," said the gentleman who
accompanied them; "they are called Secretaries, on account of the
feathers which hang behind their heads, as the feather of a pen does
when a clerk puts it behind his ear: but they are very useful, for they
are snake-killers; indeed, they would, if they could, live altogether
upon snakes, which they are very great enemies to, never letting one
escape. They strike them with their feet, and with such force as to
kill them immediately."

"Are there many snakes in this country?" inquired William.

"Yes, and very venomous snakes," replied Mr. Seagrave; "so that these
birds are very useful in destroying them. You observe, William, that
the Almighty, in his wisdom, has so arranged it that no animal
(especially of a noxious kind) shall be multiplied to excess, but kept
under by being preyed upon by some other; indeed, wherever in any
country an animal exists in any quantity, there is generally found
another animal which destroys it. The Secretary inhabits this country
where snakes exist in numbers, that it may destroy them: in England the
bird would be of little value."

"But some animals are too large or too fierce to be destroyed by
others, papa; for instance, the elephant and the lion."

"Very true; but these larger animals do not breed so fast, and