"This correspondence is of no consequence in itself, of course. But
it gives us this: Carrier pigeons will only fly home, so if Mr.
Wynne received a message by pigeon it means that at some time, within
a week say, he has shipped that pigeon and perhaps others from the
house in Thirty-seventh Street to that person who sent him the
message. If he sends messages to that person it means that he has
received a pigeon or pigeons from that person within a week. And how
were these pigeons shipped? In all probability, by express. So,
gentlemen, you see there ought to be a record in the express offices,
which would give us the home town, even the name and address, of the
person who now has the diamonds in his or her keeping. Is that clear
to all of you?"

"It is perfectly clear," commented Mr. Laadham admiringly, while the
German nodded his head in approval.

"And that is the clew we are working on at the moment," the detective
added. "Three of my men are now searching the records of all the
express companies in the city--and there are a great many--for the
pigeon shipments. If, as seems probable, this clew develops, it may
be that we can place our hands on the diamonds within a few days."

"I don'd d'ink I vould yust blace my hands on dem," Mr. Schultze
advised. "Dey are his diamonds, you know, und your hands might ged
in drouble."

"I mean figuratively, of course," the detective amended.

He stopped and drummed on his stiff hat with his fingers. Again he