the ground
wire.

Jessie had bought a galena crystal mounted, as that was more
satisfactory, the book said. After all the parts of the radio set had
been assembled and the connections made, the first essential
operation, if they were to make use of the invention at once, was to
adjust the tiny piece of wire--the "cat's whisker"--which lightly
rests on the crystal-detector, to a sensitive point.

Jessie, who had read the instruction book carefully, knew that this
adjustment might be made in several different ways. One satisfactory
way is by the use of a miniature buzzer transmitter.

"What are we going to hear?" Amy demanded eagerly. "How you going to
tune her, Jess?"

"As there are only three sets of head phones," grumbled Burd, "one of
us is bound to be a step-child."

"We can take turns," Jessie said, eagerly. "What time is it, Darry?"

"It points to eight, Jess."

"Then there is a concert about to start at that station not more than
thirty miles away from here. We ought to hear that fine," declared the
hostess of the party.

"What is the wave length?" Amy asked.

"Three-sixty. We can easily get it," and Jessie adjusted the buzzer a
little, the phones at her ears.

Eagerly they settled down to listen in. At least, three of them
listened. Darry said he felt like the fifth wheel of an
automobile--the one lashed on behind.

"I shall have to get an amplifier--a horn," Jessie murmured.

At first she heard only a funny scratchy sound; then a murmur, growing
louder, as she tuned the instrument to the required wave length. The
murmurous sound grew louder--more distinct. Amy squealed right out
loud! For it seemed as though somebody had said in her ear:

"--and will be followed by the Sextette from Lucia. I thank you."

"We're just in time," said Burd. "They are going to begin the
concert."

String music, reaching their ears so wonderfully, hushed their speech.
But Darry got close to his sister, stretching his ear, too, to
distinguish the sounds. The introduction to the famous composition was
played brilliantly, then the voices of the singers traveled to the
little group in Jessie Norwood's room from the broadcasting station
thirty miles away.

"Isn't it wonderful! Wonderful!" murmured Amy.

"Sh!" admonished her chum.

When the number was ended, Burd Alling removed his head-harness and
gravely shook hands with Jessie.

"Some calico, you are," he declared. "Don't ever go to college, Jess.
It will spoi