The discovery of the cavern made us alter our plan of bringing water to the hut. We had intended to make a reservoir just below the pipe, into which we might let water from the lake whenever we needed it; but we contented ourselves now with putting a plug into the end of the pipe, with a small hole in the middle of it, which we could stop or un-stop at will, so that by removing the stopping we should have a small trickle of water which we could collect in one of our vessels, and draw up into the hut. Having fixed these plugs, we went to the lake and filled in with our spades the excavation we had made in the side, heaping rocks about the ground that had been disturbed, so that there should be nothing to betray our device to any one who might chance to come. We then removed our V-shaped dam, and hastened back to the hut to see whether the plan answered our expectations. We found when we took out the stopping that there was a continual drip of water, which pleased us very much, for we now knew that, however long we might be shut up in the hut, we should never lack for water, and so we might be quite easy in mind. [Sidenote: Exploring] When we had finished our work in this matter of the water supply, which was a day or two after our adventure in the tunnel, we set off again, both together, to make a further exploration, only this time you may be sure we took several torches of a large size, so that the same trouble of darkness and bewilderment should not overtake us. This time also we took the precaution to close and fasten the door, for though there was little or nothing in the hut to which the dogs could do serious hurt, we preferred their room to their company, as the saying is. We went through the tunnel together, and came to the spot where my torch had gone out, and had not gone very far from thence when we found our way blocked by water, which came right into the tunnel, and which we knew by its salt taste to be the sea. It was quite plain from this that there was an outlet to the shore, but we could not tell how far it was from us, the place being exceeding dark, so that the flames of two torches held together scarce seemed to penetrate the blackness. Billy was greatly disappointed at finding our further progress thus checked, and asked me whether he should swim through the water until he came to the opening on the shore; but this I would by no means consent to, for I could have given him no light, and we could not tell what perils of sunken rocks or other things we might encounter in the darkness. And it was a mercy that Billy paid heed to my words, and was not obstinate, for if he had done what he proposed, and entered the water, I doubt not I should never have seen him again. [Sidenote: The Dogs Again]