casion. The use of the blinded carriage was a decidedly audacious
proceeding. I should put him down as a gambler of a very discreet,
courageous and resourceful type."

"Which all leads to the probability that he has pursued his scheme and
brought it to a successful issue."

"I am afraid it does. But--have you got your notes of the
compass-bearings?"

"The book is in my overcoat pocket with the board. I will fetch them."

I went into the office, where our coats hung, and brought back the
notebook with the little board to which it was still attached by the
rubber band. Thorndyke took them from me, and, opening the book, ran
his eye quickly down one page after another. Suddenly he glanced at the
clock.

"It is a little late to begin," said he, "but these notes look rather
alluring. I am inclined to plot them out at once. I fancy, from their
appearance, that they will enable us to locate the house without much
difficulty. But don't let me keep you up if you are tired. I can work
them out by myself."

"You won't do anything of the kind," I exclaimed. "I am as keen on
plotting them as you are, and, besides, I want to see how it is done. It
seems to be a rather useful accomplishment."

"It is," said Thorndyke. "In our work, the ability to make a rough but
reliable sketch survey is often of great value. Have you ever looked
over these notes?"

"No. I put the book away when I came in and have never looked at it
since."

"It is a quaint document. You seem to be rich in railway bridges in
those parts, and the route was certainly none of the most direct, as you
noticed at the time. However, we will plot it out and then we shall see
exactly what it looks like and whither it leads us."

He retired to the laboratory and presently returned with a T-square, a
military protractor, a pair of dividers and a large drawing-board on
which was pinned a sheet of cartridge paper.

"Now," said he, seating himself at the table with the board before him,
"as to the method. You started from a known position and you arrived at
a place the position of which is at present unknown. We shall fix the
position of that spot by applying two factors, the distance that you
travelled and the direction in which you were moving. The direction is
given by the compass; and, as the horse seems to have kept up a
remarkably even pace, we can take time as representing distance. You
seem to have been travelling at about eight miles an hour, that is,
rough