Their circumferences approach or intersect each other--so that, in fact, the whole country is under a network of them.

Now, as soon as one of the vultures, thus sailing about, discovers with far-seeing eye the carrion below, he immediately drops from his high orbit, and wings his way downward.

He is observed by that one circling nearest him; who, well knowing the cause of the altered flight of his companion, at once forsakes his own orbit and follows; and he, in his turn, is followed by another; and so on to the end of the chain." "But how can one of them tell that the other is gone in pursuit of prey ?" inquired Francois, interrupting Lucien in his explanation.
"Suppose you saw Basil at a great distance off on the prairie, could you not tell by his actions when he had started game, and was in pursuit of it ?" "Oh! yes! I could easily." "Well, then, the vultures, who have far keener sight than you, understand each other's movements thoroughly--even to the shaking of a feather--so that they can easily tell when one of their number has a good dinner in sight.
"I think I have shown," continued Lucien, "that they all start within a few seconds of the same time; and as they fly in a nearly direct line towards the object, if we knew the rate at which they go, it would only remain for us to mark the date of their arrival, to be able to tell how far they had come.

Of course it is supposed that we have already noted the time when the first one came upon the spot.
"If we suppose," continued Lucien, as he pointed up to the vultures, "that the first of these has alighted here two hours ago, and we allow them a flight of thirty miles an hour, we may then safely conclude that some of those now coming in have made a journey of sixty miles this morning.

What think you of my theory ?" "It is, to say the least of it, a curious one, brother," replied Basil.
"But what are they waiting for now ?" demanded Francois; "why don't they at once fall to, and enjoy it while it is fresh ?" Francois' interrogatory was a very natural one.