me waves in a whip, soft and undulating though they
be, result in a loud crack, as you know."

"Muddled again," said Johnson.

"Ditto," said Slagg.

"Why, I'm not muddled a bit!" suddenly exclaimed Stumps, with a
half-contemptuous laugh.

"Of coorse you're not," retorted Slagg. "Brainless things never git
into that state. You never heard of a turnip bein' muddled, did you?"

Stumps became vacant, and Sam went on.

"Well, you see, the waves are not substance. They are a condition--a
result of atoms in motion. Now, when the atoms of a substance are
disturbed by friction, or by chemical action, they get into a state of
violent commotion, and try wildly to fly from, or to, each other. This
effort to fly about is energy. When the atoms get into a very intense
state of commotion they have a tendency to induce explosion, unless a
way of escape is found--escape for the energy, not for the atoms. Now,
when you cause chemical disturbance in an electric battery, the energy
thus evolved is called electricity, and we provide a conductor of escape
for it in the shape of a copper or other metal wire, which we may carry
to any distance we please, and the energy runs along it, as the wave
runs along the carpet, as long as you keep up the commotion in the
battery among the excited atoms of copper and zinc."

"Mud--no, not quite. I have got a glimmer o' su'thin'," said Johnson.

"Ditto," said Slagg.

"Supper," said old Meerta.

"Ha! that's the battery for me," cried Stumps, jumping up.

"Not a bad one either," said Robin, as they entered the cave; "alternate
plates of beef and greens, steeped in some such acid as lemonade, cause
a wonderful commotion in the atoms of the human body."

"True, Robin, and the energy thereby evolved," said Sam, "sometimes
bursts forth in brilliant sparks of wit--to say nothing of flashes of
absurdity."

"An' thunderin' stoopidity," added Slagg.

Further converse on the subject was checked at that time by what Sam
termed the charging of the human batteries. The evening meal went on in
silence and very pleasantly for some time, but before its close it was
interrupted in an alarming manner by the sudden entrance of Letta with
wild excitement in her eyes.

"Oh!" she cried, pointing back to the entrance of the cave, "a ship!--
pirate-ship coming!"

A bombshell could scarcely have produced greater effect. Each
individual leaped up and darted out, flushing deep red or turning pale,
acco