t's what you thought!" blurted Delaney with loyalty.

"I was at sea," said Drew. "Now," he continued, "we have a live
cartridge at the opposite end of this core from the diaphragm. See it?"
Loris leaned over the little table.

"Right here!" The detective pointed. "That is a twenty-two cartridge
with a cupronickel bullet. See the cap? See how it is held from coming
back by those tiny screws about the rim?"

Loris nodded and gathered up her straying hair.

"Now," continued Drew. "Now, this cartridge was exploded by the action
of the human voice. Here's a tiny spiral of very slender platinum wire.
It must be number forty, at least. That's very fine! This spiral is in
series with the winding about the magnets. The same current pulsated by
the human voice which actuates the receiver diaphragm, also passed
through this spiral. Now," Drew paused. "Now," he added with rising
voice, "here is a tiny charred piece of match-head, I guess. It was set
in the coil. It flared when the wire became hot. The heat was
sufficient to ignite the cap. See it!"

"I see it!" exclaimed Nichols.

"The action is simple," continued Drew. "A pulsation of the current
which was formed by the action of the vibrating, transmitter diaphragm,
also pulsated the fine wire before it went to the receiver magnets. The
louder the voice into the transmitter the more current--measured in
fractions of amperes--passed through the spiral. It became sufficiently
hot to flare the piece of match-head or whatever Cuthbert placed there.
This flare was communicated to the percussion cap, or fulminate of
mercury, at the base of the cartridge. This exploded the powder charge,
which in turn projected the cupronickel bullet forward through the tube
or the bore of the receiver and out through the thin, metal diaphragm,
and----"

"What's that?" asked the operative.

"Out through the hole in the diaphragm," continued Drew, "and right
into your ear or my ear, Delaney!"

"Not into mine!" exclaimed the operative. "I'll never telephone as long
as I live, Chief!"

"We'll all be careful," said Nichols, turning toward Loris.

Drew gathered together the different parts of the telephone receiver.
"Evidence against Morphy," he said dryly, as he dropped them into the
side pocket of his coat. "They are our Exhibit A if he ever finishes
that twenty years in the cooler."

Loris reached out her hand. "You saved my life," she said. "You saved
it, Mr. Drew."

"I blundered and blu