In case they had scented a danger unknown to him, he cast a wide circle around them at a sharp gallop, but nothing met his nostril, his eye, or his ear except the dust with its keen taint of alkali, and the bare hills, and the vague horizon sounds.  Alcatraz came back to his companions at a halting trot which denoted his uneasy alertness.  They were milling more closely than ever.  The brood mares had passed to a sullen nervousness and were kicking savagely at everything that came near.  Decidedly something was wrong.  The wise-headed grey mare loped out to meet him and threw a course of circles around him as he came slowly forward.  Plainly she expected him to do something, but what this might be Alcatraz could not tell.  Besides, a growing thirst was making him irritable and the insistence of the grey mare made him wish to fasten his teeth over the back of her neck and shake her into better behavior.

By her antics she had worked him around to the head of the herd and she had no sooner reached this point than she threw up her head with a shrill neigh and started off at a gallop.  The entire herd rushed after her and Alcatraz, in a bound, ranged along side the grey and a neck in the lead.  While he ran he whinnied a soft question to which she replied with a toss of her head as though impatient at such ignorance.  In reality she was guiding the herd.  She knew it and Alcatraz understood her knowledge, but he made a show of maintaining the guidance, keeping a sharp outlook and turning the moment she showed signs of veering in a new direction.  Sometimes, of course, he misread her intentions and swerved across her head and on each of these occasions she reached out and nipped him shrewdly.  Alcatraz was too taken up in his wonder at the actions of the herd to resent this insolence.  For half an hour they kept up the steady pace and then Alcatraz literally ran into the reason.

It was a beautiful little lake, bedded in hard gravel and maintained by a dribble of water from a brook on the north shore.  Alcatraz snorted in disgust at his folly.  What had disturbed them was exactly what had disturbed him—­thirst.  He controlled his own desire for water, however, and followed an instinct that made him draw back and wait until all the rest—­the oldest stallion and the youngest colt—­had waded in and plunged their noses deep in the water.  Then he went to the lake edge a little apart from the rest and drank with his reflection glistening beneath him.

It was a time of utter peace for the chestnut.  While he drank he watched the line of images broken by the small waves in the lake and listened to the foals which had only tasted the water and now were splashing it about with their upper lips.  For his own part he did not drink too much, since much water in the belly makes a leaden burden and Alcatraz felt that, as leader, he must always be ready for running.  A scrawny colt, escaping from the heels of a yearling floundered against him.  Alcatraz