we'll
look over the set-up. The apparatus is strewn all over the place."

He had not exaggerated. The set-up consisted of a whole bank of tubes,
each one in its own shielding copper box. On a much-drilled horizontal
panel, propped up on insulators, were half a score of delicate meters of
one kind and another, with thin black fingers that pulsed and trembled.
Behind the panel was a tall cylinder wound with shining copper wire, and
beside it another panel, upright, fairly bristling with knobs, contact
points, potentiometers, rheostats and switches. On the end of the table
nearest the door was still another panel, the smallest of the lot,
bearing only a series of jacks along one side, and in the center a
switch with four contact points. A heavy, snaky cable led from this
panel to the maze of apparatus further on.

* * * * *

"This is the control panel," explained Mercer. "The whole affair, you
understand, is in laboratory form. Nothing assembled. Put the different
antennae plug into these jacks. Like this."

He picked up a weird, hastily built contrivance composed of two
semi-circular pieces of spring brass, crossed at right angles. On all
four ends were bright silvery electrodes, three of them circular in
shape, one of them elongated and slightly curved. With a quick, nervous
gesture, Mercer fitted the thing to his head, so that the elongated
electrode pressed against the back of his neck, extending a few inches
down his spine. The other three circular electrodes rested on his
forehead and either side of his head. From the center of the contrivance
ran a heavy insulated cord, some ten feet in length, ending in a simple
switchboard plug, which Mercer fitted into the uppermost of the three
jacks.

"Now," he directed, "you put on this one"--he adjusted a second
contrivance upon my head, smiling as I shrank from the contact of the
cold metal on my skin--"and think!"

He moved the switch from the position marked "Off" to the second contact
point, watching me intently, his dark eyes gleaming.

Carson entered, and Mercer gestured to him to wait. Very nice old chap,
Carson, impressive even in his bathing suit. Mercer was mighty lucky to
have a man like Carson....

* * * * *

Something seemed to tick suddenly, somewhere deep in my consciousness.

"Yes, that's very true: Carson is a most decent sort of chap." The words
were not spoken. I did not _hear_ them,