ger you said you found in the empty house?"

"Here it is. And it's a very unique weapon."

Old King Brady held up the knife.

It had a double-edged blade, eight inches long, as thin as paper, and
was embossed with the initials P. V., in frosted letters.

"What an ugly-looking weapon!" Harry commented, with a shudder.

"It's an oddity," replied the old detective. "But it isn't a certainty
that these are the initials of the person who last used it."

"You'd better keep those three things," advised Harry, thoughtfully.
"They may come in handy if this case amounts to anything."

"If they serve us no better purpose, we can show them to our chief when
we get back to New York, so he will have evidence of what we are
doing," said Old King Brady, with a faint smile.

"He expected a report from us to-night, on the case he put us on, but
he won't get it," said Harry, grimly.

The boy referred to some work they had been doing before they stumbled
upon the Thirty-sixth street affair.

Information had reached the Central Office that Oliver Dalton, a Broad
street broker, suspected his nephew, Ronald Mason, of robbing his mail.

The detectives had gone to the broker's house in West Thirty-eighth
street to get the particulars privately. But the man's daughter,
Lizzie, told them her father had not yet come home. They waited for him
till nearly eight o'clock, and as Mr. Dalton did not appear, they were
going back to headquarters when they stumbled upon the suspicious case
already recorded here.

Old King Brady smiled at Harry's remark.

"There's no great hurry about that case," he remarked.

"Well," said the boy, "are you ready to go through the cars on a hunt
for Solomon Gloom? We must make sure of our man before he has a chance
to alight at a way station and elude us."

Old King Brady bent nearer to Harry, to reply, when suddenly a cloth
was thrown over their heads by a man who sat behind them.

The cloth was saturated with chloroform.

While the detectives were struggling to extricate their heads, they
inhaled the deadly fumes and were overcome by the drug.

Not until they were fast asleep did the man remove the cloth.

No one had seen the deed, as they occupied the last seats in the aisle
and not an undue noise had arisen to attract attention.

Seeing the detectives stupid from the drug, a low chuckle escaped the
man, and he rose to his feet and muttered:

"Sleep, you dogs! Tracked me, eh? Well, it won't do you