"What's that? No, not that schooner below there—I mean that sort of whitish drift—it looks like cotton—on the horizon?"

Jess leaned forward and addressed Jimsy.

"You've got me guessing," rejoined that slangy young person.

"Ask Peggy."

"No, I don't want to bother her now. She's got her hands full, I fancy."

The Golden Butterfly was swinging steadily onward above a sparkling sea. The slight haze perceptible from the land was not noticeable to the air voyagers. Below them a four-masted schooner was tacking in the light wind. Closer in shore lay several grim looking battleships and cruisers. In their leaden colored "war paint" they looked menacing and bulldoggish.

Far off, a mere speck, could be seen a dim and indistinct object pointing upward from the cape like a finger. They guessed it was the light for which they were aiming. Peggy's last glance at the compass had confirmed this guess.

Jimsy looked about him. About a quarter of a mile off, and slightly ahead was the Cobweb. The silvery aeroplane was rushing through the atmosphere at a great rate. But profiting by Mortlake's experience, Fanning was evidently not speeding the 'plane to its fullest capacity.

On the other side was a large red biplane flying steadily and keeping about level with the Golden Butterfly. Far behind lagged a monoplane. The other contestants had dropped out of the race. They were so manifestly out of it that their drivers did not care to continue.

A glance at the speedometer showed Peggy's two passengers that they were reeling off fifty-five miles an hour. The Cobweb was doing slightly better.

"We should round the light in a few minutes now," said Jimsy scrutinizing his watch anxiously.

"Will they report us?" asked Jess.

"Yes. There is a wireless rigged up there. The minute we round it on our return trip word will be flashed back to the starting point."

Silently they sat counting the minutes roll by. All at once Jimsy noticed that the air had become strangely damp and moist. He looked up. He could not refrain a cry of astonishment as he did so. The Golden Butterfly was enveloped in a damp, steamy sort of smother. The Cobweb had been blotted out and so had the other aeroplanes.

"Fog," he exclaimed. "What a bit of bad luck."

"It's just as bad for the others," Peggy reminded him.

"Have you got your course?" asked Jess anxiously.

"Yes. Almost due east. But in this dense mist it will be hard to come close enough to the lighthouse to be reported without the danger of dashing into it."

"Are you going to try for it?"

"Of course," was the brief reply. Peggy slowed down the engine. The Golden Butterfly now seemed to be gliding silently through lonely billows of white sea fog. It was an uncanny feeling. The occupants of the machine felt a chilling sense of complete isolation.

Thanks to their barograph, however, they could judge their height above the sea.

"Good thing we've got it," commented Jimsy; "otherwise we might have a thrilling encounter with the topmasts of some schooner."

"I only wish we had some instrument to show us where the other aeroplanes are," said Peggy; "it's hard to hear anything in this fog."

"Maybe it will clear off," suggested Jess hopefully.

"Not unless we get some wind," opined Jimsy; "queer how quick that wind dropped and this smother came up."

Nobody even hinted at the deadly danger they were in. But each occupant of the Golden Butterfly knew it full well. Except for the compass, they had no way of guiding their flight, and to turn about would have been to court disaster. There was only one thing for it, to keep on. This Peggy did, grimly compressing her lips.

"Hark!" exclaimed Jimsy suddenly.

Far below them they could hear a mournful sound. It was wafted up to them in fits and starts.

"Ding-dong! Ding-dong!"

"A church bell," cried Jess, "we must be over land, Peggy!"

The other shook her head.

"That's a bell buoy, I guess," she said.

"I wish he'd tell us how to get out of here," joked Jimsy, rather wearily.

"Who?" asked Jess.

"That bell boy."

Never had one of Jimsy's jokes fallen so flat. He mentally resolved not to attempt another one.

Presently he looked at his watch.

"Almost eleven," he said, "we must have passed the light by this time."

"I don't know," said Peggy helplessly; "if only the chart marked that bell buoy—but it doesn't."

She again scrutinized the chart pinned before her on the sloping slab designed for such purposes. But no bell buoy was marked on it as being located anywhere near where they estimated they must be drifting. Drifting, however, is not quite the correct word. An aeroplane cannot drift. Its life depends upon its motion. The instant it stops or decreases speed beyond a certain point, in that same instant it must fall to the earth.

This fact is what made the position of the young sky cruisers particularly dangerous. Although the gauge showed that they had plenty of gasoline, the supply—even with the use of the auxiliary tanks—would not hold out indefinitely. If the fog did not lift, or they did not land, sooner or later they must face disaster. Worse still, they were—or believed they were, navigating above the sea.

Had the Golden Butterfly been fitted with pontoons like some of the Glen Curtiss machines, this would not have been so alarming. But a descent into the ocean would inevitably mean a speedy death by drowning.

Suddenly voices struck through the smother all about them. They seemed to come from below.

"It's thick as pea soup, captain!"

"Aye, aye; I'll be glad when we're out of it I kin tell yer. This bay's a bad place ter be in er fog."

"A ship," cried Jimsy. "Quick, Peggy," he almost yelled the next instant. "Set your rising levers."

The girl swiftly manipulated the machinery that sent the Golden Butterfly on an upward course.

But it was only just in time that this maneuver was carried out. All of them had a glimpse for an instant of the gilded ball on the main-mast head of the vessel beneath them. For an instant Peggy's watchful eye had been deflected from the height gauge, and she had allowed the Golden Butterfly to drop almost on the top of some coasting vessel's mast.

The danger over, they could not help laughing at the whimsical adventure.

"Just to think how utterly unconscious those fellows were of the fact that three human beings were hovering right above them and listening to every word of their conversation," chuckled Jimsy; "isn't it queer?"

A little while later a steamer's whistle boomed through the fog beneath them, but as the altitude register showed five hundred feet, they did not bother about it.

"At all events we know we're still above the water and not in danger of colliding with any church steeples," said Jess, and she found consolation in the thought.

"Have you any idea at all as to the direction of the light, Peggy?" inquired Jimsy at length.

"I—I really don't know," confessed Peggy, with a gulp; "everything's mixed up. It's so thick I can't tell anything and I'm deathly afraid of running into the lighthouse by mistake."

"Then for goodness sake give it a wide berth," cried Jimsy; "if we keep on cruising about for a while we'll be bound to land somewhere. Anyhow we've got lots of gasoline, that's one comfort."

It was, indeed. In the steady hum of their powerful motor the young aviators found consolation in that lonely ride through the billowing fog-banks. At all events, there was no sign of a falter or skip there.

"If only we could get some wind," sighed Jess.

"Might as well wish for the moon," said Jimsy; "the air is as still as it used to be at noon out on the desert."

"What a contrast between the Big Alkali and this!" cried Jess, half hysterically. The strain of the white drifting fog was beginning to tell upon her.

Jimsy looked at her sharply.

"Look here, Sis," he began and was going on when a sharp cry from Peggy arrested him. At the same instant the Golden Butterfly swerved sharply, swinging over on her beam-ends almost.

Right in front of them, for one dreadful instant, there loomed the outlines of another aeroplane. The next instant it was gone. But the picture of the deadly peril, its outlines exaggerated by the mist, was photographed in the minds of every one of them.

"We must land somewhere, soon," said Peggy, in rather a faint voice; "I don't think I could stand many shocks like that. Another inch, and——."

She did not complete the sentence. Her two listeners did not require her to. It did not take a vivid imagination to have pictured the result of that "other inch."