Burke nodded.  “Been closed ever since the last arrest.  There’s a servant who goes in now and then, but the car hasn’t been there before to-night, wherever it has been.”

“I should like to watch that house myself for a while,” mused Kennedy.  “I suppose you have no objections to my doing so?”

“Of course not.  Go ahead,” said Burke.  “I will go along with you if you wish, or my man can go with you.”

“No,” said Kennedy, “too many of us might spoil the broth.  I’ll watch alone to-night and will see you in the morning.  You needn’t even say anything to your man there about us.”

“Walter, what’s on for to-night?” he asked when they had gone.  “How are you fixed for a little trip out to Riverwood?”

“To tell the truth, I had an engagement at the College Club with some of the fellows.”

“Oh, cut it.”

“That’s what I intend to do,” I replied.

It was a raw night, and we bundled ourselves up in old football sweaters under our overcoats.  Half an hour later we were on our way up to Riverwood.

“By the way, Craig,” I asked, “I didn’t like to say anything before those fellows.  They’d think I was a dub.  But I don’t mind asking you.  What is this ‘portrait parle’ they talk about, anyway?”

“Why, it’s a word-picture—­a ‘spoken picture,’ to be literal.  I took some lessons in it at Bertillon’s school when I was in Paris.  It’s a method of scientific apprehension of criminals, a sort of necessary addition and completion to the methods of scientific identification of them after they are arrested.  For instance, in trying to pick out a given criminal from his mere description you begin with the nose.  Now, noses are all concave, straight, or convex.  This Forbes had a nose that was concave, Burke says.  Suppose you were sent out to find him.  Of all the people you met, we’ll say, roughly, two-thirds wouldn’t interest you.  You’d pass up all with straight or convex noses.  Now the next point to observe is the ear.  There are four general kinds of ears-triangular, square, oval, and round, besides a number of other differences which are clear enough after you study ears.  This fellow is a pale man with square ears and a peculiar lobe to his ear.  So you wouldn’t give a second glance to, say, three-fourths of the square-eared people.  So by a process of elimination of various features, the eyes, the mouth, the hair, wrinkles, and so forth, you would be able to pick your man out of a thousand—­that is, if you were trained.”

“And it works?” I asked rather doubtfully.

“Oh, yes.  That’s why I’m taking up this case.  I believe science can really be used to detect crime, any crime, and in the present instance I’ve just pride enough to stick to this thing until—­ until they begin to cut ice on the Styx.  Whew, but it will be cold out in the country to-night, Walter—­speaking about ice.”