pieces of candy, but aside from this, nothing seemed
to have been damaged seriously.

Jimmy's followed Bob's gaze, and, finding his precious sweets upon the
floor, began gathering them up hastily, stuffing a doughnut in his mouth
to help him hurry. What mattered it to Jimmy that the floor was none too
clean?

"Say, what's the big idea, anyway," Joe demanded of the blackened Herb.
"Trying to start a Fourth of July celebration, or something?"

"I was just mixing some chemicals, and the result was a flare-up,"
explained Herb sulkily. "Now, stop rubbing it into a fellow, will you?
You might know I didn't do it on purpose."

Bob began to laugh.

"Better get in connection with some soap and water, Herb," he said.
"Just now you look like the lead for a minstrel show."

"Never mind, Herb," Joe flung after the disconsolate scientist as he
made for the door. "As long as you don't hurt anything but Jimmy's
doughnuts, we don't care. You can have as many explosions as you like."

"Humph, that's all right for you," retorted Jimmy. "But I'll have you
know I spent my last nickel for those doughnuts."

"Just the same," said Bob soberly, as they returned to the problem of
the vacuum tube, "we're mighty lucky to have come off with so little
damage. Mixing chemicals is a pretty dangerous business unless you know
just what you're doing."

"And even then it is," added Joe.

CHAPTER IX

A HAPPY INSPIRATION

The days passed by, the boys becoming more and more engrossed in the
fascination of radio all the time. They continued to work on their sets,
sometimes with the most gratifying results, at others seeming to make
little headway.

But in spite of occasional discouragements they worked on, cheered by
the knowledge that they were making steady, if sometimes slow, progress.

There were so many really worth-while improvements being perfected each
day that they really found it difficult to keep up with them all.

"Wish we could hear Cassey's voice again," said Herb, one day when they
had tuned in on several more or less interesting personal messages.

"I don't know what good it would do us," grumbled Joe. "If he speaks
always in code he could keep us guessing till doomsday."

"He's up to some sort of mischief, anyway," said Bob; "and I, for one,
would enjoy catching him at it again."

"We would be more comfortable to have Dan Cassey in jail, where he
belongs," observed Jimmy.

But just at present the trailing of t