“I have some in my pocket,” said Ulfin, blushing, only she could not see that. “They keep me busy making nets in my spare time—I always have some string in my pocket.” A piece of stringy seaweed suddenly became visible as Ulfin took it out of his invisible pocket, which, of course, had the property of making its contents invisible too, so long as they remained in it. It floated toward the Princess, who caught the end nearest to her and held it fast. “Where are you?” said a small voice. It was Mavis—and almost at once Francis and Bernard were there too. The seaweed chain was explained to them, and they each held fast to their ends of the seaweed links. So that when the soldiers, a little late in the day, owing to the careful management of Ulfin’s friend, reached the front door, there was nothing to be seen but four bits of seaweed floating down the street, which, of course, was the sort of thing that nobody could possibly notice unless they _knew_. The bits of seaweed went drifting to the Barracks, and no one noticed that they floated on to the stables and that invisible hands loosed the halters of five Sea Horses. The soldier who ought to have been looking after the horses was deeply engaged in a game of Animal Grab with a comrade. The cards were of narwhal ivory, very fine, indeed, and jeweled on every pip. The invisible hands saddled the Sea Horses and invisible forms sprang to the saddles, and urged the horses forward. The unfortunate Animal Grabber was roused from his game by the sight of five retreating steeds—saddled and bridled indeed, but, as far as he could see, riderless, and long before other horses could be got out and saddled the fugitives were out of sight and pursuit was vain. Just as before they went across country to the rock cut and then swam up, holding by the linking seaweed. Because it was Tuesday and nearly two o’clock, the Professor of Conchology was making ready to receive pupils, which he did in an arbor of coral of various shades of pink, surrounded by specimen shells of all the simpler species. He was alone in the garden, and as they neared him, the Princess, the three children and Ulfin touched the necessary buttons and became once more visible and tangible. “Ha,” said the Professor, but without surprise. “Magic. A very neat trick, my dears, and excellently done.” “You need not remove your jacket,” he added to Ulfin, who was pulling off his pearly coat. “The mental exercises in which we propose to engage do not require gymnasium costume.”