oil which is undoubtedly diatomaceous."

"That sounds awful."

"Diatoms in a fossilised condition are silicious, and they are to be
found in Virginia, in Bermuda, and here."

"Professor, I am an ignoramus."

"Then it is my duty to inform you that the man or woman who drinks
water from that spring is swallowing millions of tiny flint knives,
hard as diamond dust--indeed, diatomaceous earth is used commercially
as a polishing powder."

"You mean that if we drink that water we shall be polished off?"

The Professor glared. Like many distinguished scientists, he took
himself seriously, and he knew that this was a serious matter.

"Those tiny flint knives cut to ribands the mucous membrane."

"Fortunately," said Ajax, "we don't drink that water. The spring was
only developed a few days ago." In a graver voice he continued: "We
are exceedingly obliged to you. Of course we shall warn our men."

"Has nobody drunk of that spring?"

Ajax thought that he detected a note of disappointment. He replied
reflectively: "I don't think so. The cattle have used it. It doesn't
seem to have affected them."

"Are you sure of that?" he demanded sharply.

"You can ask our foreman."

Later, the Professor did so. Uncle Jake came out of the corrals,
carrying a branding-iron and found himself confronted by a short,
thick-set man with prominent, slightly congested grey eyes, which
shone keenly out of an immense head.

"I am Professor Chawner, of the Smithsonian. I wish to ask you a
question."

"Perfessor, I'm happy to meet ye. It tickles me to death to answer
questions. And I stand by the editor o' _The Tribune_. If I kin
co-operate in yer important work, why, count me in."

The Professor raised his grizzled brows in astonishment, but he said
politely--

"I am very much obliged to you. My question is this: 'Do the cattle
drink at the spring which bubbles out of that hill yonder?'"

"Some of 'em do."

"Regularly?"

"Not to say reglerly, Perfessor. It's this way with cattle on a ranch
as well watered as ours. They drink when they feel like it, and they
drink where the water is handy to the feed. Come to think of it, there
never has been much feed around that spring; and it never flowed good
and hard till we opened it a few days ago."

"Since you opened it, to your personal knowledge, have cattle drunk of
it?"

Uncle Jake scratched his head. The Professor's manner was impressive.

"Have you seen cattle actually drinking t