I thought he was spinning a yarn at the time."

"You were wrong, Willis; he likewise told us that sound travels at the
rate of four hundred yards in a second."

"Well, but--"

"Have patience, Willis! When the lightning flashes, the electric spark
is discharged, is it not?"

"Well, I was never high enough aloft to see."

"But others have been; Newton and Franklin have seen it. Now, if the
sound reaches our ears a second after the flash, it has travelled four
hundred yards. If we hear it twelve or thirteen seconds after, it has
travelled twelve or thirteen times four hundred yards, or about half a
mile, and so on."

"But what has that to do with your pulse?"

"In the first place, I am in perfect health, am I not?"

"I hope so, Master Jack."

"Then when our systems are in good order, the pulse, keeping fractions
out of view, beats once in every second; and consequently, though we
do not always carry a watch, we always have our arteries about us, and
may therefore always reckon time."

"Now I understand."

"Ah! then we are to escape this time without the 'Mariner's March.'"

"It appears, Master Jack, that you have turned philosopher as well as
your brothers. Can you tell me what causes lightning?"

"Yes, I can, Willis. You must know, in the first place, that all the
layers of the atmosphere are, more or less, charged with electricity."

"Ask him how," said Fritz drily.

"Ah, you hope to puzzle me," replied Jack, "but thanks to Mr. Wolston,
I am too well up in physics to be easily driven off my perch, and
therefore may safely take my turn in philosophising."

"Well, we are listening."

"The air, by means of the vapor it contains, absorbs electricity from
terrestrial bodies, and so becomes a sort of reservoir of this
invisible fluid. All chemical combinations evolve electricity, the air
collects it and stores it up in the clouds. There, worshipful brother,
your question is answered."

"Good, go on."

"Well, Willis, you must know, in the second place, the clouds are very
good fellows, and share with each other the good things they possess.
When one cloud meets another, the one over-supplied with this fluid
and the other in its normal state, there is an immediate interchange
of courtesies, the negative electricity of the one is exchanged for
the positive of the other."

"There does not appear, however, to be much generosity in this
transaction, since the surcharged cloud does not cede its superfluous