wink wheeler reached the little channel first and gingerly climbed out on a brown ledge that flanked it on one side. others joined him there to lie panting in the sunlight. only joe and phil kept on and were presently swimming within a short distance of each other well outside. they were both strong rather than fast swimmers, and, although han frowned slightly as he watched them bob in and out of sight in the long, smooth swells, the others soon turned their attention to wink's suggestion that they dive from the rock and race around the anchored boats and back again. wink offered the others a ten-yard start. all save "brownie" accepted the challenge—"brownie" was built for comfort rather than speed—and in a moment they were lined up rather unsteadily on the edge of the boulder awaiting the word. then three bodies launched themselves through the air and the race was on. when the others had taken the first half-dozen strokes after reappearing wink plunged after them. "brownie" watched until the foremost swimmer disappeared beyond the boats and then turned his gaze seaward. for a moment he could not find the two venturesome ones, but presently he spied them. they had turned and were coming back straight for the mouth of the little harbour, phil leading and joe a dozen yards behind. it looked like a race from the way in which both boys were keeping under and "brownie" found it more exciting than the other contest. and then, while he watched, something happened, and he sprang to his feet and gazed seaward with wildly beating heart.

joe had stopped swimming and was on his back with one brown arm held aloft. if he made any outcry "brownie" failed to hear it, but apparently he had, for phil was turning now and hurrying back with short, quick strokes. but before he had covered half the distance separating him from the other, the watcher on shore uttered an involuntary cry of alarm. joe was no longer in sight!

"brownie" looked despairingly toward the boys in the pool, but the nearest was still a long way from the channel. confused thoughts of the boats were cast aside and "brownie" threw himself from the rock, hitting the water like a barrel, and turned into the channel. as he felt the tug of the tide he experienced a revulsion of fright, for he had no stomach for the task ahead of him. "brownie's" swimming was usually done in safer water than that he was making for. but he tried his best to forget the depths below him and the long swim ahead, to remember only that joe was in trouble out there and that phil, probably by now somewhat exhausted, would never be able to bring him to shore unassisted.

the long swells hid the others from him. once, though, poised for a moment on the round summit of a bank of water, he glimpsed ere he descended into the green valley beyond, a darker spot ahead and so found his direction. he knew better than to tire himself out by desperate strokes. his only hope of getting there and getting back was to conserve his strength. all sorts of thoughts came and went in a strange jumble. sometimes it seemed that he was making no progress, that the slow waves were bearing him remorselessly back to the cove, or, at least just defeating the strokes of his arms and legs. breathing became laboured and once a veritable panic seized him and it was all he could do to keep from turning and swimming wildly back toward shore. instead, though, fighting his fears, he turned on his back for a moment with his round face to the blue breeze-swept sky, and took long, grateful breaths of the sun-sweet air. above him a grey gull swept in a wide circle, uttering harsh, discordant cries. then, his panic gone, "brownie" turned over again and struggled on with renewed strength and courage. and suddenly, the long swells were behind him and there, but a few yards away, was phil, phil very white of face but as calm as ever.

he was swimming slowly on his side, one arm cleaving the water and the other supporting the nearly inert body of joe. "here comes 'brownie,'" the rescuer heard him say cheerfully. "all right now, joe. we'll get you in in a jiffy! roll over, 'brownie,' and get your breath," he added. "we're all right for a minute. that's the trick."

"i'm—a bit—tuckered," gasped "brownie," as he lay and puffed with outstretched arms.

"don't blame you," said phil. "how are you now, joe?"

"punk," muttered the other. "don't you fellows bother too much. if you'll just stay by for a minute or two—i'll be—um—all right, i guess."

"no need to do that," replied phil quietly. "'brownie' and i will take you between us. put a hand on my shoulder. easy, son! that's it. now the other on 'brownie's.' right you are. just let yourself float. ready, 'brownie?' don't hurry. easy does it. we've got an eighth of a mile or so and there's no use getting tired at the start. i guess the tide will help us, though."

there were no more words until the shore was nearly reached. by that time "brownie" was frankly all-in and phil was in scarcely better condition. joe had so far recovered then, however, as to be able to aid weakly with his legs, and before they reached the channel half a dozen eager helpers splashed to their assistance. anxious questions were showered on them, but only joe had the breath to answer them.

"i had a cramp," he explained apologetically. "it hit me all of a sudden out there. it was fierce!"

"legs?" asked steve.

"no—yes—about everywhere below my shoulders. it seemed to start in my tummy. i got sort of sick all over. thought—um—thought i was a goner until—"

"all right! shut up now. someone give phil a hand. he's about ready to quit. 'brownie,' too." steve and wink had taken the places of the rescuers and joe was finishing his journey at top speed. it was no easy task getting him aboard, but they finally accomplished it and hurried him below. "brownie," too, had to be pushed and pulled over the side, and while phil got aboard almost unaided he slumped onto a seat and, to use perry's expression, "passed out." hot coffee and many blankets and at least three different remedies from the medicine chest presently left joe out of pain, while in the case of phil and "brownie" the hot coffee and rest were alone sufficient.

breakfast was rather late that morning, and joe's place was vacant, for that youth was enjoying a sleep in the after cabin. "brownie" and phil, however, recovered wonderfully at the sight of bacon and eggs and did full justice to the repast. steve laid down the law during breakfast as follows:

"after this there'll be no more swimming away from the boats, fellows. we came on this trip for fun and not funerals. you took a big chance, phil, when you went that far out. this water's about ten degrees colder than what you and joe are used to. it's a wonder you didn't both have cramps and drown."

"i guess it was rather foolish," agreed phil. "the water was a lot colder out there than inside, too. still it didn't bother me any." he lowered his voice, with a glance toward the companion way and the other cabin. "i thought old joe was a goner, though, fellows. i was about forty feet away, i suppose, when i heard him yell, and before i could get back he'd gone down. i was afraid he meant to keep on going, but he thrashed his way up again and i managed to grab him. the trouble was then that he wanted to drown both of us and i had a hard time making him see reason."

"someone ought to recommend you for the carnegie medal, phil," said han, with a laugh that didn't disguise his earnestness.

phil shook his head. "i wasn't the hero of the adventure," he replied quietly. "i'm fairly at home in the water and i've done four miles without tiring much. it's 'brownie' who deserves the medal, fellows. he saw joe go down and jumped right in and beat it out there; and you all know that 'brownie' isn't any swimmer. i think he was just about scared to death!"

"i'll bet he was," agreed steve. "he's never been known to go ten yards from shore or boat. yes, i guess 'brownie' is the real hero, as you say, phil."

"he certainly is, because i'll tell you frankly that i never could have got joe in alone. i was just about used up by the time we'd tried to drown each other out there."

"we didn't know anything about it," explained ossie, filling phil's cup again unasked, "until someone happened to look from the follow me and saw you three out there. it was tom corwin, i think. i heard him yelling—i was getting my clothes on down here—and i ran up on deck and then grabbed the megaphone and shouted to steve and wink and the others who were over on the rock near the inlet. by the time they got it through their thick heads—"

"thick heads be blowed!" exclaimed steve disgustedly. "you were just yelling a lot of words that didn't mean anything. if you hadn't kept on pointing we'd never have known what was up. we all thought you had a fit."

all's well that ends well, however, and an hour after breakfast the incident was, if not forgotten, dismissed. joe reappeared, looking rather pale still, but announcing himself quite all right. "i was nice and sick at my tummy," he explained, "and now i feel fine."

"being sick at your tummy," remarked perry unkindly, "is quite the best thing you do, joe. if you can't be sea-sick you go and try to drown yourself!"

of course "brownie" was allowed to surmise that he had done something rather big, and joe thanked him very nicely, but mr. carnegie is still in ignorance of his exploit!

the two boats floated out of the pool about ten and set off for bar harbor. the barely averted tragedy somewhat modified their regret at leaving titania's mirror and mystery island. later, steve and joe tried to locate that island on the charts but without certain success. there were so many islands thereabouts that neither dared to more than guess at the identity of the one they had visited. looking back at it from a distance of a half-mile they saw that it was in reality much smaller than they had supposed, being scarcely more than a huge rock pushed up from the ocean bed. ossie, who had a leaning toward geology, furnished the theory that mystery island was no more nor less than the top of an extinct volcano and that titania's mirror was the crater.

"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."

they went on, all save the disapproving trio, perry and wink wheeler leading the way up the winding avenue toward the glow of fairy lights ahead. no one challenged them, although they were observed with curiosity by several servants before they came out on a wide lawn in front of a spacious residence. fully a hundred guests were already assembled. a platform overhung by twinkling and vari-coloured electric lamps had been laid for dancing and, as the uninvited guests paused to survey the scene, an orchestra, hidden by shrubbery and palms in tubs, started to play. chairs dotted the lawn and a big marquee was nearby. on a low terrace in front of the hospitable doorway of the residence the hostess was receiving as the carriages rolled around the immaculate drive and stopped to discharge the guests. the boys viewed each other questioningly. perry pulled down his waistcoat and walked boldly across the lawn and the drive and stepped to the terrace. wink followed unhesitatingly, but the others hung back for a moment. then they, too, approached, their assurance oozing fast. they reached the terrace in time to witness perry's welcome.

"good evening," said that youth in bored and careless tones, shaking hands with the middle-aged lady. "awfully jolly night, isn't it!"

"how do you do, mister—ah—so glad you could come. yes, isn't it splendid to have such perfect weather? marcia, you remember mister—ah—"

perry was passed on to a younger lady, evidently the daughter of the house.

"howdy do?" murmured the latter, shaking hands listlessly.

"how do!" returned perry brightly. "bully night, eh!"

"yes, isn't it?" drawled the young lady. then perry gave place to wink.

"good evening," said wink, grinning blandly.

"howdy do? so nice of you to come," murmured the lady. wink joined perry and they crossed to the other side of the terrace and maliciously watched the embarrassment of the other boys. joe and harry corwin carried things off rather well, but the others were fairly speechless. perry chuckled as he saw the growing bewilderment on the face of the hostess. but finally the ordeal was over and perry led the way back to the festivities. ossie groaned when they were safely out of ear-shot.

"she's on to us," he muttered. "i could see it in her eye! i'm off before they throw me out!"

"don't be a jay," begged perry. "the evening's young and the fun's just starting. mrs. thingamabob doesn't know whether she asked us or not. i'm going to see what's in the big tent over there. come on, fellows."

they went, dodging their way between chattering groups and impeding chairs, but when perry peered through the doorway of the marquee he was met with a chilly look from a waiter on guard there. "supper is at ten o'clock, sir," said the servant haughtily.

"that's all right," replied perry kindly. "don't hurry on my account, old top!"

what to do for the succeeding hour was the question, for, while all save perry and ossie danced more or less skilfully, they knew no one to dance with. "if you ask me," remarked cas temple, yawning, "i call this dull. i'd rather be in my bunk, fellows."

"well, let's find something to do," said joe. "maybe they've got a roller-coaster or a merry-go-round somewhere. let's—um—explore."

by this time the dancing had begun in earnest and the platform was well filled with whirling couples. the boys paused to look on and, since the throng was growing larger every minute, were forced to change their position more than once with the result that presently perry, wink and ossie found themselves separated from their companions. they looked about them unavailingly and waited for several minutes, and then, as the others did not appear, went on.

"we'll run across them," said perry cheerfully. "let's stroll around and see who's here."

"awfully mixed crowd," said wink. "really, you know, mrs. jones-smythe should be more particular. why, some of the folks don't look as though they had ever been invited!"

"i know," agreed perry, with a sigh. "society's going to the dogs these days. one meets all sorts of people. it's perfectly deplorable."

"beastly," agreed ossie, stumbling over a chair. "bar harbor's getting very common, i fear."

"hello, that's pretty!" exclaimed perry. they had emerged onto a walled space that looked straight out over the water. hundreds of lights dotted the purple darkness and the air held the mingled fragrance of sea and roses. "this isn't so punk, you know," continued perry, leaning over the wall. "maybe this would suit me as well as an island."

"you're on an island," ossie reminded him.

"i meant a real island," murmured perry. ossie was about to argue the matter when footsteps approached and they moved off again. a flight of steps led to a stone-floored verandah and they went up it and perched themselves on the parapet, to the probable detriment of the ivy growing across it, and watched the colourful scene. they were quite alone there, for the porch was detached from the terrace that crossed the front of the house. two french windows were opened and beyond them lay a dimly-lighted library. perry, hugging one foot in his hands, looked in approvingly.

"whoever owns this shanty knows what's what," he said. "just have a squint at all those books, will you? millions of them! wonder if anyone has ever read them."

"well, i'm glad i don't have to," said wink feelingly. "but that's a corking room, though. these folks must have slathers of money, fellows."

"oh, fairly well fixed, i dare say," responded perry carelessly. "say, what time is it! feed begins at ten, and with all that mob down there it's the early bird that's going to catch the macaroons. wonder if they'll have lobster salad."

"nothing but sandwiches and ices, i guess," said ossie. "i wouldn't object to a steak and onions, myself. funny how hungry you get up in this part of the world."

"you sure do," agreed wink. "let's move along. if the corwin family gets in there ahead of us we might just as well pull in our belts and beat it."

"let's go in through here," said perry. "it's nearer, i guess." he started toward the first window.

"oh, we'd better not," ossie objected. "they might not like it."

"piffle! they'll be tickled to death. they like folks to see their pretties." he stepped through the window and, dubiously, his companions followed. the library was a huge apartment, occupying, as it seemed to them, more than half the length of the house, with several long windows opening onto the terrace at the front. the furnishings were sombrely elegant and the dim lights caught the dull polished surface of mahogany and glinted on the gold-lettered backs of the shelf on shelf of books that hid the walls. deep-toned rugs rendered footsteps soundless as they made their way toward the wide doorway at the far end of the room. they had traversed barely a third of the distance when a sudden sound brought them up short.

one of the windows that opened onto the terrace further along swung inward and a middle-aged man in evening attire stepped into the room. perry, in spite of his former assurance, drew back into the shadow of a high-backed chair, stepping on wink's foot and bringing a groan from that youth. the newcomer, however, evidently failed to hear wink's protest, for, closing the window behind him in a stealthy manner, he crossed the further end of the library and paused beside a huge stone fireplace. wink and ossie had dropped to the protecting darkness of a big table, but perry still peered, crouching, from behind the chair. in the dim light of an electric lamp the intruder's face had shown for an instant, and in that instant perry had sensed it all! the stealthy manner of the man's entrance from the terrace instead of by the door, the plainly furtive way in which he crossed the room and the anxious expression of his face, a face which perry saw at once to be criminal, was enough! the watcher was not in the least surprised when the man, hurriedly and still stealthily, drew out a square of mahogany paneling at the left of the fireplace and revealed the front of a small safe. perry's heart began to thump agitatedly at the thought of witnessing a robbery. the man's fingers worked deftly at the knob. perry could hear in the silence the click of the tumblers as they slid into place. then the door was pulled open.

between perry and the robber lay a full thirty feet of floor, and a big table impeded his progress, but it took the boy less than a second to cover the distance, to seize the robber from behind, pinioning his arms, and to bear him heavily back to the floor.