by any chance cause a spark when they walked over her metal floors
and ladders just beneath her great bag."

"That is true," vouched John Ross. "One little spark reaching any of
that stored hydrogen would have torn that great dirigible into
fragments in one gigantic blast."

"We have handled recent newspaper copy containing mention of this new
gas, helium; but I must confess I am in the dark regarding its nature
and source," said Mr. Giddings. "What is it, anyway?"

"I will refer your question to Paul here," replied John. "He is the
one who worked out this idea of using helium in an airplane and giving
it the best properties of a dirigible without any of the dirigible's
handicap of clumsiness and excessive wind resistance. He has been
studying the properties of helium in school, also the flight of birds."

"Well, not to get into a tiresome discourse, as Professor Herron would
say, I shall make this description very rudimentary," said Paul, with a
smile. "During a total eclipse of the sun in India in 1868, Lockyer, a
British astronomer, saw in the spectroscope a bright, yellow line of
light around the sun. He called it _helium_, after the Greek word for
sun. So much for him. Twenty-seven years later an element was found
on earth in natural-gas in Kansas, which gave the same bright, yellow
light viewed through the spectrum. The people, finding it would not
burn, disgustedly let millions of barrels of this valuable element
escape into the air, before a scientist told them that it was of untold
value for balloon and airship purposes. It is thought the gas comes
from radium deposits. It has never been found in any country except
the United States, and only here in Kansas and northern Texas, where it
occurs in sands from 14,000 to 16,000 feet deep. Our government is now
securing about 50,000 cubic feet of helium per day, refusing to sell it
to foreign countries, as it is all needed here, besides which it might
be used against us in case of another war."

While Paul had been telling this, Mr. Giddings had been busy jotting
something down in shorthand in a notebook.

"Pardon me, Paul," he said, looking up with a smile, "but this is so
mighty interesting that, before I knew it, my old-time reportorial
instinct had gotten the best of me, and I found my pencil at work. If
you have no objection I should like to use this in the columns of the
_Daily Independent_ some time when it seems to fit in."

"No objection