Several were coiled to strike, and had, in accordance with their habit, sounded their rattles.  This had aroused the whole den, many snakes appearing from under ground, or crawling from beneath stones.

“Come on!  They’ll chase us!” cried Bob.

“Nonsense,” replied the professor.  “Rattlesnakes never attack man unless they are first disturbed.  It wouldn’t be advisable to go too close, but, as long as we don’t molest them, we have nothing to fear from the snakes.  I’d like to get a few specimens if I had the proper appliances for extracting their fangs.  But I never saw so many in one place, before.  It is quite interesting to watch—­”

The professor broke off suddenly, for the thunderous noise of the approaching steers was now louder.

“They’re coming right at us!” exclaimed Jerry.

“Yes, and they’ve stampeded!” cried Ned.  “We’re in for it now!”

The situation of the boys and the professor was extremely perilous.  They were right in the path of the now frightened steers.  The circle had been broken, by many animals, which had been approaching from the rear of the travelers, joining the beasts on either side, so that now a compact, dark mass of cattle, nearly a quarter of a mile wide, was surging ahead with great speed.

“Run!” called Ned.  “There’s an opening at our backs now!”

“You couldn’t go a hundred feet before they’d overtake you!” shouted Jerry.  “Let’s see if we can’t frighten ’em.  Take off your hats, jump up and down, and yell like mad.  If we can force ’em to separate and go on either side of us, we’ll be all right!”

He started to swing his hat in the air, and prepared to let out a series of yells in imitation of an Indian war-whoop.

“Don’t!” cried the professor quickly.

“Why not?” asked Jerry.  “It’s the only way to stop ’em.”

“I know a better, and a surer way,” replied the scientist.  “Get the rattlesnakes between ourselves and the cattle!  Those steers will never go near a rattlesnake den, no matter how frightened they are, nor how badly stampeded!  Quick!  Here they come!”

The cattle were scarcely two hundred feet away, and were maddened by the sight of unmounted persons, something to which they were unaccustomed, and which thoroughly frightened them.  The ground was trembling with their hoof-beats, and the rattle of the horns, as they clashed together, was like the murmur of cannibal tom-toms.

The professor grabbed Bob, who was nearest him, and swung the boy around, so as to get the nest of rattlesnakes between them and the steers.  Ned and Jerry followed.  The snakes, now all aroused, were rattling away like half a hundred electric batteries working at once.

Would the professor’s ruse succeed?  Would the steers be afraid to come over the deadly reptiles, to trample down the little group, which the animals probably took for some new species of enemy?  These were questions which the boys waited anxiously to have answered.  Nor did they have to wait long.