leton stared at the master mechanic for a moment, pulling
ruminatively at his brier; then--they were in the super's office at the
time--his fist came down with a sudden bang upon the desk.

"I believe you've got it, Tommy!" he exclaimed.

"Believe I've got it!" echoed Regan, and his hand half-way to his mouth
with his plug of chewing stopped in mid-air. "Got what? I said he
wasn't blind in the other, and neither he is--you know that as well as
I do."

"Wait!" said Carleton. "It's very rare, I know, but it seems to me
I've heard of it. Wait a minute, Tommy." He was leaning over from his
chair and twirling the little revolving bookcase beside the desk, as he
spoke--not a large library was Carleton's, just a few technical books,
and his cherished Britannica. He pulled out a volume of the
encyclopedia, laid it upon his desk, and began to turn the leaves.
"Yes, here it is," he said, after a moment. "Listen"--and he commenced
to read rapidly:

"'The most common form of Daltonism'--that's color-blindness you know,
Tommy--'depends on the absence of the red sense. Great additions to
our knowledge of this subject, if only in confirmation of results
already deduced from theory, have been obtained in the last few years
by Holmgren, who has experimented on two persons, each of whom was
found to have _one color-blind eye_, the other being nearly normal."

"Color-blind!" spluttered the master mechanic.

"In one eye," said Carleton, sort of as though he were turning a
problem over in his mind. "That would account for it all, Tommy. As
far as I know, one doesn't go color-blind--one is born that way--and if
this is what's at the bottom of it, Owsley's been color-blind all his
life in one eye, and probably didn't know what was the matter. That
would account for his passing the tests, and would account for what
happened at Elbow Bend. It was the patch that did it--you remember
what he said--the light was white as the moon."

"And he's out!" stormed Regan. "Out for keeps--after forty years.
Say, d'ye know what this'll mean to Owsley--do you, eh, do you? It'll
be hell for him, Carleton--he thinks more of his engine than a woman
does of her child."

Carleton closed the volume and replaced it mechanically in the bookcase.

Regan's teeth met in his plug and jerked savagely at the tobacco.

"I wish to blazes you hadn't read that!" he muttered fiercely. "What's
to be done now?"

"I'm afraid there's only one thing to be