[Illustration:  Figure 2]

The actual adjustment of the detector is rather a delicate job, and once it is in the proper position it is a good plan to avoid jarring it, as it is liable to get out of adjustment very easily.

Once the sensitive spot on your detector is found, slowly turn the knob on your condenser and at some spot on it you should be able to pick up signals of some sort, either of radiophone or spark.  If the set does not work, then go over all your wiring and be sure that the windings of the two coils are both running the same way.

The above set will work well for short distances, say up to twelve or fifteen miles.  Beyond that, however, it will not receive music unless you have unusual facilities for putting up an aerial to a considerable height and well clear of surrounding objects.

Such a set should be constructed at a minimum of cost and may later, after you have become familiar with the operation of radio appliances, easily be converted into a set of much greater range by the use of a vacuum tube as detector and may even, by slight changes, be given the much desired regenerative effects.

CHAPTER I

A CRY IN THE AIR

“Well, Bob, here we are again.  And no word from Jack yet.”

“That’s right, Frank.  But the weather has been bad for sending so great a distance for days.  When these spring storms come to an end the static will lift and well stand a better chance to hear from him.”

“Righto, Bob.  Then, too, the Hamptons may not have finished their station on time.”

The other shook his head.  “No, Jack wrote us they would have everything installed by the 15th and that we should be on the lookout for his voice.  And when he says he’ll do a thing, he generally does it.  It must be the weather.  Let’s step out again and have a look.”

Taking off their headpieces, the two boys opened the door of the private radiophone station where the above conversation took place and stepped out to a little platform.  It was a mild day late in June, and the sandy Long Island plain, broken only by a few trees, with the ocean in the distance, lay smiling before them.  A succession of electrical storms which for days had swept the countryside in rapid succession apparently had come to an end.  The clouds were lifting, and there was more than a promise of early sunlight to brighten the Saturday holiday.

The boys looked hopefully at each other.

“Looks better than it has for days, Frank.”

“That’s right.”

A few moments more they chatted hopefully about the prospects, then re-entered the station.

Frank Merrick and Bob Temple were chums, a little under 18 years of age each.  It was their bitterest regret that they had been too young to take any part in the World War some years before.  Frank was dark, curly-haired, of medium height and slim, but strong and wiry.  Bob was fair and sleepy-eyed, a fraction under six feet tall and weighed 180 pounds.  A third chum and the leader of the trio was Jack Hampton, 19 years of age.  He had gone to New Mexico several months before with his father, a mining engineer.