with the sentiments that they had expressed; whereat
he smiled with quiet amusement.

"I thought," he remarked, "that letter would bring Marchmont to our door
before long. As to Winwood, I have never met him, but I gather that he
is one of those people whom you 'mustn't mind.' In a general way, I
object to people who tacitly claim exemption from the ordinary rules of
conduct that are held to be binding on their fellows. But, as he
promises to give us what the variety artists call 'an extra turn,' we
will make the best of him and give him a run for his money."

Here Thorndyke smiled mischievously--I understood the meaning of that
smile later in the evening--and asked: "What do you think of the affair
yourself?"

"I have given it up," I answered. "To my paralysed brain, the Blackmore
case is like an endless algebraical problem propounded by an insane
mathematician."

Thorndyke laughed at my comparison, which I flatter myself was a rather
apt one.

"Come and dine," said he, "and let us crack a bottle, that our hearts
may not turn to water under the frown of the disdainful Winwood. I think
the old 'Bell' in Holborn will meet our present requirements better than
the club. There is something jovial and roystering about an ancient
tavern; but we must keep a sharp lookout for Mrs. Schallibaum."

Thereupon we set forth; and, after a week's close imprisonment, I once
more looked upon the friendly London streets, the cheerfully lighted
shop windows and the multitudes of companionable strangers who moved
unceasingly along the pavements.

Chapter XV

Thorndyke Explodes the Mine

We had not been back in our chambers more than a few minutes when the
little brass knocker on the inner door rattled out its summons.
Thorndyke himself opened the door, and, finding our three expected
visitors on the threshold, he admitted them and closed the "oak."

"We have accepted your invitation, you see," said Marchmont, whose
manner was now a little flurried and uneasy. "This is my partner, Mr.
Winwood; you haven't met before, I think. Well, we thought we should
like to hear some further particulars from you, as we could not quite
understand your letter."

"My conclusion, I suppose," said Thorndyke, "was a little unexpected?"

"It was more than that, sir," exclaimed Winwood. "It was absolutely
irreconcilable either with the facts of the case or with common physical
possibilities."

"At the first glance," Thorndyke agreed, "it w