We shan't get down to the cave to-day." As far as they could tell they were unobserved the next afternoon, and after exercising plenty of caution they reached the mouth of the little river tunnel and dropped down out of sight one after the other in an instant.

In fact, so quick was their disappearance that it would have puzzled the keenest searcher as to where they had gone.

For one moment they were standing upon a piece of lichen-covered granite, the next they had leaped in among the brambles, which parted for them to pass through and sprang up again, the lads dropping on to the old stream bed, which they had carefully cleared of stones.

They left no footmarks there, and they were careful to preserve the thin screen of ferns and bramble, so that a watcher would have credited them with having ducked down and crept away.
This ruse, trifling as it may seem, added to their enjoyment of their hiding-place, and as soon as they were in darkness they struck a light and went on down to the caves, had a look round, and Mike immediately began to get down the fishing lines which hung from a wooden peg driven into a granite crack.
"Never mind the fish to-day," said Vince, who was busily fixing a fresh piece of candle in the lanthorn.
"Why?
We're not hungry now, but we shall be before we go back.

Hullo! what are you going to do ?" "Wait a bit, and you'll see," replied Vince, who now took a little coil of rope from where it hung, and then asked his companion's assistance to extricate something which he had placed in the belt he wore under his jersey.
"Why, whatever have you got here ?" "Grapnel," was the reply; and Vince began to rub the small of his back softly.