"It probably sank, like lots of them did," he elaborated, "and the sea wore away part of it and flowed into the crater. I'm pretty sure that that rock we climbed out on this morning when we were swimming was volcanic." "Sure," agreed Perry. "It was pumice stone. I meant to bring a bit of it along for you to clean your hands with." "I didn't say pumice," replied Ossie haughtily. "It was more probably obsidian." "My idea exactly! In fact, it had a very obstinate feeling. It--it left quite an impression on me!" The _Follow Me_ developed engine trouble that morning and they lay by for a half-hour or more while Tom Corwin toiled and perspired, argued and threatened. It was well after two o'clock when they ran up the eastern shore of Mount Desert Island and finally dropped anchor in Frenchman's Bay. They ate only a luncheon on board and then clothed themselves in their gladdest raiment and went ashore. They "did" the town that afternoon, mingling, as Wink said, with the "haut noblesse," and had dinner ashore at an expense that left a gaping hole in each purse. But they were both hungry and glad to taste shore food again, and no one begrudged the cost. It was when they were on their way back to the landing that the glow of coloured lanterns behind a trim hedge drew their attention to the fact that someone was conducting a lawn party. The imposing entrance, through which carriages were coming and going, met their sight a moment later and inspired Perry with a brilliant idea. "Say, fellows, let's go," he said, as they paused in a body to allow a handsome landau to enter. "I've never been to one of these lawn fêtes, or whatever they call them in the society papers, and here's the chance." "Anybody invited you?" drawled Joe. "No, but maybe they meant to. You can't tell. Maybe if they knew we were here--" "Might send word in to them," suggested Wink Wheeler. "Say that the crews of the _Adventurer_ and the _Follow Me_ are without and--" "Yes, without invitations," agreed Perry. "I get you, but that might cause our hostess embarrassment, eh? Why not just save her all that by dropping in sociably?" "Are you crazy?" demanded Steve. "Crazy to go and see all the pretty lanterns and things, yes. And maybe they'll have a feed, fellows! Come on! Take a chance! They can't any more than put us out! Besides, they probably won't know whether they invited us or not. It's just a lark. Be sports, fellows!" The notion appealed to most of them, but Steve and Phil and Bert Alley declined to countenance it. "What will happen to you," said Steve grimly, "is that you'll all spend the rest of the night in the town jail for impersonating gentlemen!" "Oh, if that's all you're afraid of," responded Perry sweetly, "you might as well come, too, Steve. They'd never charge _you_ with that." "Sub-tile, sub-tile," murmured Cas Temple. "Anyhow, our clothes are perfectly O.K.," continued Perry. "White trousers and dark coats are quite _de rigor_. Come on, fellows."