were caught and sent. Within the hut was the rest of the wireless apparatus, which, with the exception of some improvements of Frank’s devising, was of the portable kind—the same in fact that they had used in Florida. Outside the hut was a small shelter covering a four horse-power gasolene engine, which generated the power for the station.

As most boys are familiar nowadays with the rudiments of wireless telegraphy we are not going into technical details concerning the plant. Suffice it to say that the boys were able to converse with Portland, under favorable conditions, and judged that, in suitable weather, they had a radius of some two hundred and fifty miles.

But it was off to one side of the clearing, the side nearest to the cove, that the most interesting structure on the island was situated. This was more of a covering than a shed, for it consisted merely of a roof supported with uprights; but in bad weather canvas curtains could be drawn so as to make its interior stormproof.

This shed was now open, and under the roof could be seen what was perhaps at the moment the most unique machine of its kind in the world. Looking into that shed you would have said at first that it housed a boat. For the first object that struck your eye was a double-ended, flat-bottomed craft of shimmering aluminum metal, about thirty feet in length and built on the general lines of one of our life-saving craft. That is to say, with “whalebacks” at each end containing air chambers, and plenty of beam and room within the cockpit. A peculiar feature, however, was the addition of four wheels.

But the boat theory would have had to be abandoned the next moment, for above the hull of the whaleboat-shaped craft was what appeared to be the understructure of an aëroplane. But the planes—the broad wings—themselves were lacking. The twin propellers connected to a motor within the boat were, however, in place. Apparently they were driven by chains, similar to, but stouter than, the ordinary bicycle variety.

All about was a litter of tools and implements of all kinds. Several large frames leaning against one side of the shed appeared to be the skeleton forms of the wings which were soon to be added to the superstructure.

“Tamales and terrapins!” cried Pudge admiringly, as he gazed at the uncompleted craft, “but she begins to look like something, eh, Frank?”

“Yes,” nodded the young aviator, “but until your father arrives we cannot adjust the wings. There is a lot of theoretical work connected with them that he will have to do. By the way, I wonder if Portland’s got any answer to our message yet?”

Followed by the others, Frank entered the living hut, which proved to be a snug, neat compartment about fifteen feet in length, by ten in width. It had four windows, two on a side, and a door at one end. At the other end was the wireless apparatus, with its glittering bright metal parts, and businesslike-looking condensers and tuning coils. Along the walls were four bunks, two on a side, one above the other. In the center were a table and camp chairs, and from the ceiling hung a large oil lamp.

A shelf held a good collection of books on aëro and wireless subjects, and at one side of the door was a blue-flame kerosene stove. On the other side of the door was a cupboard containing crockery, knives, forks and cooking utensils. Altogether, if the boys had not been there for a more serious purpose, the place might have been said to form an almost ideal camp for four healthy, active lads.

“Start up the motor, Harry,” said Frank, as soon as they had deposited their burdens, “and we’ll try and get some track of Dr. Perkins. His answer to our message ought to be in Portland by now.”

The younger Chester lad hastened outside, and soon the popping of the motor announced that it was running. Frank sat down at the key and, depressing it, sent a blue-white flame crackling across the spark gap. Out into space, from the aërials stretched above, the message went volleying. It was the call of the Portland station that Frank was sending. He flashed it out three times, as is customary, and then signed it F-C., the latter being Brigg Island’s agreed-upon signature. Then, while the others gathered round, Frank adjusted the “phones,” the delicate receivers that clamp over the ear and through which, by way of the detector, any message vibrating in the air may be caught as it encounters the antenna.

Frank listened some time but—save for the conversation of two wireless operators far out at sea—he could hear nothing. With a gesture of impatience Frank began adjusting his tuning coil. All at once he broke into a smile of satisfaction. At last Portland was answering:

“F—C! F—C! F—C!”

“All right,” rejoined Frank, sending a volley of sparks crashing and flashing across the gap as soon as he could break in, “is there any answer to my message?”

“Yes. Perkins will be at Motthaven to-morrow night. He wants you to meet him,” came back the answer, winging its way over the intervening miles of space.

“Is that all?”

“That’s all.”

Frank removed the “phones,” grounded his key and told Harry he could stop the motor.

“I’ll be glad when the doctor does get here,” he confided to the others, after he had communicated the message, “for I’m beginning to think that we are in for some sort of trouble. Those two Daniels are pretty influential in the village, and it only needs a word from them to turn the whole crowd against us.”

“We could stand ’em off,” bragged Pudge grandiloquently, “lassoes and lobsters, we could stand ’em off. I half wish they would come—buttons and buttercakes, but I do!” and Pudge doubled up his fists and looked fierce.

“You forget, Pudge,” said Frank, “that we are here in positions of responsibility. All this property is your father’s. It is our duty to see that no harm comes to it. A bunch of those fishermen inflamed by anger might be able to do more harm here in an hour than could be repaired in months, not to mention the cost.”

“Surely you don’t think they’d come down to actual violence, Frank?” inquired Harry.

“I don’t know. The two Daniels looked mighty savage to-day, I can tell you. If it hadn’t been for the electric fence they might have made trouble. At all events I’ll be glad to have some advice.”

CHAPTER III.—A NIGHT ALARM.

After supper that night, a meal consisting of fried salt pork, boiled potatoes and some fresh fish which Frank had caught earlier in the day, the elder of the Chester lads called what he termed “a conference,” although Billy Barnes declared it was more in the nature of a “council of war.”

We are not going to detail here all that was said as it would make wearisome reading; but, after an hour or more of talk, Frank spoke his mind.

“It may be all foolishness, of course,” he said, “but I think that we ought not to leave the island unguarded to-night. Daniels and his son have had a taste of that wire fence and they may have figured out some way to get around it—it would be a simple enough matter to do, after all.”

“Well, what’s your proposal?” inquired Billy Barnes.

“To patrol the island all night, taking turns on watch. It’s not more than a mile or so all round it, and it ought to be an easy matter to keep the ground thoroughly covered.”

“Rifles and