"Now then, sit fast," cried the latter object of his thoughts; "and if we are capsized, girls, I'll look after you, Maddy. Pradelle here will swim out with Louie, and I shall leave you to bring out the boat, Leslie. You can swim, can't you?" "A little," said the young man dryly. Pradelle looked rather more green, for the light within the cave was of a peculiar hue, and he began to think uneasily of bathing out of a machine at Margate, holding on to a rope, and also of the effort he once made to swim across a tepid bath in town. But he laughed heartily directly after as he realised that it was all banter on his friend's part, while, in spite of himself, he gave a sigh of relief as, riding out on the crest of a broken wave, they once more floated in the sunshine. Ten minutes' careful rowing among the rocks, which were now four or five feet beneath the water, now showing their weedy crests above, brought them to the mouth of another cave, only approachable from the sea, and sending the boat in here, the collection went on till it was deemed useless to take more specimens, when they passed out again, greatly to Pradelle's satisfaction. "How's time?" said Harry. "Half-past four? Plenty of time. High tea at six. What shall we do--sail right out and tack, or row along here in the smooth water among the rocks?" "Row slowly back," said Louise; and Pradelle took an oar. At the end of half a mile he ceased rowing. "Tired?" said Harry. "No; I have a blister on my hand; that's all." "Come and pull, Leslie," said Harry. "You'd better steer, Louie, and don't send us on to a rock." The exchange of places was made, and once more they began to progress with the boat, travelling far more swiftly as they glided on close in to the mighty cliff which rose up overhead, dappled with mossy grey and patches of verdure, dotted with yellow and purple blooms. "To go on like this for ever!" thought Leslie as he swung to and fro, his strong muscles making the water foam as he dipped his oar, watching Louise as she steered, and seemed troubled and ready to converse with Pradelle whenever she caught his eye. "Starn all!" shouted Harry suddenly, as about three miles from home they came abreast of a narrow opening close to the surface of the water. The way of the boat was checked, and Harry looked at the hole into which the tide ran and ebbed as the swell rose and fell, now nearly covering the opening, now leaving it three or four feet wide. "Bound to say there are plenty of good specimens in there," he said. "What do you say, Vic, shall we go in?" "Impossible." "Not it. Bound to say that's the opening to quite a large zorn. I've seen the seals go in there often." "Has it ever been explored?" said Leslie, who felt interested in the place. "No; it's nearly always covered. It's only at low tides like this that the opening is bared. If the girls were not here I'd go in." "How?" said Pradelle. "How?--why swim in."