Burdale, indeed, seemed to have a good deal of information to give about the fens; and Jack could not help thinking that he must belong to the country, or, at all events, have lived a considerable time in it. Indeed, no one but a person thoroughly acquainted with the nature of the ground could have managed to find his way across it. The water was soon over the horses' fetlocks, and here and there up to their knees. More than once Jack could not help fearing that his guide had made a mistake, and that he was leading him into dangerous country; but he did not wish to show any suspicion of his judgment, and made no remark. Again the horses rose up out of the slough across which they had been wading and enjoyed for a short time some hard ground; but they soon had to leave it, to wade on as before. On every side was heard the loud croaking of frogs; their heads poked up in all the shallower marshes, with the object, it seemed, of observing the travellers, and then their croaking became louder than ever, as if they were amusing themselves by talking about them. "We call those animals `Holland-waits,'" observed Burdale. "Their king must look upon himself as fortunate, for he has got a large number of subjects; but they're not so bad as the midges. If you were to cross where we are on a hot day, with the sun broiling down on your head, you would wish you had a thick net over your face, for they do bite mortal hard!" Burdale's horse seemed better accustomed to the country than was Jack's. After having gone a considerable distance, he left Jack some way behind. The marks of the horse's feet had immediately been lost, by the spongy ground returning to its former state. Jack, however, thought there could be no difficulty in pushing on directly behind him. He had not, however, gone far before he found that, instead of following Burdale's direction to turn neither to the right nor left, he had by some means got off the track. His horse began to flounder, and the more he floundered the more difficult it was to extricate himself. Deeper and deeper he sank into the mire, till Jack, fearing that he might lose him altogether, shouted out to Burdale. Burdale heard his voice at length, and hurried back to his assistance. Jack had already got off his horse into the mud, hoping in that way to relieve the poor animal, but it did but little good, and he himself was also sticking fast! "Here, catch hold of the end of this rope!" exclaimed Burdale, as he threw one which was secured to his saddlebow. "I will haul you out; and then, maybe, we will get the horse free. You could not have followed my advice, or this would never have happened." Happily, Jack soon reached firm ground, and then he and Burdale together managed to get out the unfortunate horse.