ng at this blotter."

"Whatever is there funny about that?" demanded the other, in puzzled
tones, as he glanced first at the object in question, and then up at the
face of his chum.

"It was a new one, or nearly so, you see! and somebody has been writing
heavily, and then pressing the blotter over it," Frank went on.

"And if you could read backwards now, you might make out what they said;
is that it, Frank?"

"Oh! that part is as easy as falling off a log. I held it up to the
looking glass here. See if you can make it out, Andy."

Hardly had the other looked than he started to read, interjecting
remarks of his own as he proceeded.

"Some words missing, looks like, Frank; let's see; 'Car on
siding----'rive at 11 P.M. Wed. He says keep low, and trust to
him--throw--track. Mum.' That's all I can make out, because he didn't
sign any name, it seems. Whatever do you make of all that stuff, Frank?"

First of all Frank pulled out a pencil and copied the marks upon a piece
of paper, which he thrust into his pocket.

"He might miss the blotter if I cribbed it, and take the alarm," he
explained, as he hastened to put the article in question back on the
table, lest Sallie come in at any minute and discover what they were
doing, taking liberties in the room of the boarder; and then she would
have to be told everything, which might work out badly, Frank feared.

"But I reckon you've got some sort of idea what that writing means,
Frank?" pursued the other Bird boy, who, once he started on a subject
could no more be shaken off than a bulldog.

"Of course I have, and it's given me something of a shock, too, let me
tell you, Andy. First of all, you may know that this very day is
Wednesday."

"The day he mentions there; to be sure it is. But Frank, can all this
have some reference to another crime they mean to commit?"

"I'm afraid it does," came the reluctant reply.

"Tell me what he means by 'car, siding, track, mum,' and all that. Of
course I can understand that he warns the fellow he's sending the
message to to keep quiet. What car can he mean? Do you think they aim to
steal some one's expensive car now--that they've gone and wrecked
Percy's biplane, and must have another means for getting away?"

But Frank simply shook his head at that.

"Oh! you're away off your base there, Andy. He speaks of a car on a
siding, and that can only refer to a railroad car. Now, I happen to know
that they expect the pay-car to be alon