IN THE DARK
"Now," continued Dr. Dale, as he glanced round the circle of eager
faces, alight with interest in the subject, "we're getting pretty
close to the time when one picks up the receiver and begins to listen
in.
"But as the electric vibrations, if left alone, would have a good deal
of trouble in passing through the telephone receiver, we must have a
condenser to help them out. This is very easily made by gluing a piece
of tinfoil about one and a half inches square to each side of a sheet
of mica. Then you must have two strips of tinfoil, one extending from
each side of the mica. If you haven't any mica, a sheet of ordinary
writing paper will do, though the mica is better.
"The telephone receiver you will have to buy, as a satisfactory one
can't very well be made by an amateur. The receiver ought to have a
high resistance to get the best results.
"There," he said, as he laid the telephone receiver on the bench,
"those are the essential things you have to have in order to make
a set of your own. With these things only, it will of course be a
simple set and have a limited range. There are a hundred improvements
of one kind or another that you'll learn about as you get more expert,
and these can be added from time to time. But the special thing I
wanted to prove to you to-day was that it would take only a very small
expenditure of money to get this material together. You see how many
things I've used that any one of you can find about the house, such
as tinfoil, curtain poles, curtain rings, wood for the box, and so on.
The wire needed for your tuning coil and your aerial can be obtained
for less than a dollar. The detector, including the crystal, can be
got for another dollar. An excellent receiver can be bought for two
dollars. A few minor things will be needed at perhaps five or ten
cents each. Altogether the cost of the set can be brought within
five dollars."
This was good news to the boys, many of whom began at once a mental
calculation as to the amount of their pocket money, while others began
to figure on odd jobs that might bring them in the required amount,
in the event that their parents would not supply the money.
With a few deft movements the doctor attached the various parts of
the apparatus to their proper places on the baseboard. There was
not time that day to put up the aerial, but he gave them practical
illustrations of how to use the detector by pressing the point of the
wire firmly against the crystal, how to slide the rings back and forth
until they found the point of greatest loudness and clearness, and all
other points essential to using the set successfully. Not all the boys
caught on to all that was involved, but to the majority it was made
reasonably clear. To Bob and Joe, who had followed every point of
the demonstration with the keenest attention, the operation of the
receiving set was made as clear as crystal, and they had no doubt
of their ability to construct a set for themselves. Herb's attention
had wandered somewhat, because in the back of his mind there still
lurked the idea of buying a set ready made. Jimmy had been somewhat
distracted by looking about in various parts of the barn to see if he
could detect the presence of any "eats," and his ideas were somewhat
hazy in consequence.
"Well, boys," at last said the doctor, with a smile, "I guess we'll
call it a day. But remember that if at any time you are puzzled and
want more information all you have to do is to come and ask me. I'll
gladly lay aside my work any time to help you youngsters out."
The boys thoroughly appreciated the doctor's cordiality and the
demonstration that he had given them, and most of them took occasion
to tell him so as they said good-bye to him and filed out of the
extemporized workshop.
"He certainly does make things clear," said Bob enthusiastically,
as he and his friends made their way toward their homes.
"Not only that, but he makes you want to do them," said Joe. "After
seeing and hearing him this afternoon, I'd ten times rather make
a set than buy one."
Jimmy agreed with them, and even Herb seemed ready to reconsider the
idea of getting one ready made, though he was not yet quite prepared
to surrender.
"All of you come over to my house to-night," said Bob, as they neared
their homes. "We haven't got the materials yet, but we can go over
again what the doctor told us to-day and make sure that we've got it
all straight in our minds. What one forgets, the other may remember.
Then when we do get the stuff we can put a little snap and speed into
making the set."
"That will be bully," replied Joe, and the others agreed with him.
"For my part," Joe continued, "I count every day lost that we have
to go without it. I sure am becoming a radio fan."
It turned out that Herb was prevented from coming by unexpected
company but the others were there. Their talk that night was animated
and enthusiastic, so much so in fact that the time passed more quickly
than they imagined, and they were surprised when the clock struck
eleven.
"By the way," said Jimmy, as he was preparing to leave with the rest,
"I had a run in with Buck Looker when I was coming here to-night,
and he said he was going to lay for me and do me up."
"He did, did he?" asked Bob. "What was he sore about?"
"Oh, he's had a grouch ever since the day of the fire," replied Jimmy.
"You remember that when he spoke of the work he'd been doing to help
put out the fire, I spoke up and said that he hadn't done a thing.
He's had it in for me ever since. He bumped against me on purpose
to-night just as I was coming in the gate, and when I called him down
for it he said he was going to lay for me and change my face."
"The big bully!" exclaimed Bob. "Just wait here a minute while I go
into the next room."
The adjoining room was dark and commanded a view of the street in
front, while Bob himself could look out of the window without being
seen. Some large shade trees were on the other side of the street,
and as Bob's eyes became accustomed to the darkness, he could dimly
descry three forms lurking in the shadows. One of them he felt sure
was Buck, and he felt reasonably certain that the others were Carl
Lutz and Terrence Mooney, Buck's boon companions.
"I guess Buck and his gang are hanging around all right," he
announced, as he returned to the other room and reported his
discovery. "But he's going to get a little surprise party. I tell you
what we'll do. You go out of the front door alone, Jimmy. Joe and I
will stand there in the light from the hall lamp and say good-night.
Then we'll close the door, and you stand on the stoop a minute,
buttoning your coat, and then go slowly down the walk. That will give
Joe and me a chance to slip around through the back in the darkness
and get behind the bushes near the gate. Leave the rest to us."
"And what we'll do will be a plenty," added Joe.
Jimmy thought well of this plan, and agreed to do his part.
They followed out this program to the letter. As Jimmy came down the
walk, the lurking figures across the street came out from the shadow
of the trees and over toward him.
"I've got you now, Jimmy Plummer," snarled the voice of Buck Looker.
"I told you I was going to take some of the freshness out of you,
and now I'm going to tan your hide."
"Does it take three of you to do it?" asked Jimmy.
"None of your lip now," growled Buck, as he clenched his fist.
"I'm going to have the fun of doing it myself."
With one spring Bob vaulted over the low fence.
"You've got another guess coming, Buck Looker," he said coolly.
The bully started back in surprise and consternation, which was not
diminished when Joe followed his friend's example and stood at his
side.
"What are you butting in for?" Buck snapped, as soon as he recovered
his breath.
"Because I choose to," answered Bob. "Because I won't stand by and see
you hit a fellow half your size. If it's fighting you're looking for,
I'll give you all the fighting you want right here and now. If your
gang want to mix in, Joe will take care of Lutz and Jimmy can look
after Mooney. But I'll take you on myself. How about it? Is it a go?"
He advanced on Buck, and before his flashing eyes those of the bully
wavered and fell.
"I--I'll settle with you some other time," he stammered, retreating
toward the middle of the street.
"No time like the present," challenged Bob, but as Buck, muttering
threats, still continued to retreat, while his cronies slunk away
with him, Bob gave a little laugh and came back to his friends.
"All right, Jimmy," he chuckled. "I guess your face won't be changed
to-night. Buck seems to have changed his mind."