Mr. Vane was delighted.  There was a good deal of the boy about him still; he loved anything in the shape of a bit of fun, and he loved boating.  So off the two came, and were most pleasantly welcomed by old Tobias and his second-in-command at the lighthouse.  And by another happy chance, just as Biddy began to wade, Mr. Vane had come to the side of the lantern-room looking over in her direction.

‘What can that be, moving slowly through that bit of water?’ he said to Tobias.  ‘I am rather near-sighted.  Is it a porpoise?’

‘Nay, nay, sir, not at this season,’ replied the old man; ’besides it’s far too shallow for anything like that, though there is a deepish hole near the middle.’

He strolled across to where Mr. Vane was standing as he spoke, and stared out where his visitor pointed to.  Then suddenly he flung open one of the glazed doors and stepped on to the round balcony—­perhaps that is not the right word to use for a lighthouse, but I do not know any other—­outside, followed by Mr. Vane.  Just then Biddy’s screams came shrilly through the clear afternoon air, for it was a still day, and out at the lighthouse, when there was no noise of wind and waves, there was certainly nothing else to disturb the silence except perhaps the cry of a sea-gull overhead, or now and then the sound of the fishermen’s voices as they passed by in their boats.  And just now the waves were a long way out and the winds were off I know not where—­all the better for the poor silly child, who, having got herself into this trouble, could do nothing but scream shrilly and yet more shrilly in her terror.

Old Tobias turned and looked at Mr. Vane.

’It’s a child, ‘pon my soul, it’s a child,’ he exclaimed, and he sprang inside again and made for the ladder leading downstairs.  But quick as he was, his visitor was before him.  People talk of the miraculous quickness of a mother’s ears; a father’s, I think, are sometimes quite as acute, and Bridget’s father loved dearly his self-willed, tiresome, queer-tempered little girl.  Long before he got to the top of the ladder he knew more than old Tobias, more than any of them—­Mr. Mildmay or young Williams, the other lighthouse man—­had any idea of.  He knew that the voice which had reached him was that of his own Biddy, and before Tobias could give him a hint, or ever a word had been said as to what was best to do, he had pulled off his coat, tossed away his hat, and was up to his waist in the water.  For though not so deep close round the lighthouse as at the dangerous place where Biddy had lost her head, this salt-water lake even at low tide was never less than two or three feet in depth at the farther side.

‘I can swim,’ was all Mr. Vane called out to the three hurrying after him.  But so could Mr. Mildmay, and so could, of course, Tobias and Williams.  And it was not so much the fear of his friend’s drowning as the thought of the mischief that might come to him, delicate as he was, from the chill and exposure, that made Mr. Mildmay shout after him, ‘Come back, I entreat you, Vane; you are not fit for it,’ while he struggled to drag off a very heavy pair of boots he had on—­boots he had on purpose for rough shingly walking, but which he knew would weight him terribly in the water.