tand that you wrote to your son
upon the day when this incident occurred."

"No, I wrote upon the day before."

"Exactly. But he received it on that day?"

"Yes."

"Was there anything in your letter which might have unbalanced him or
induced him to take such a step?"

"No, sir, certainly not."

"Did you post that letter yourself?"

The nobleman's reply was interrupted by his secretary, who broke in with
some heat.

"His Grace is not in the habit of posting letters himself," said he.
"This letter was laid with others upon the study table, and I myself put
them in the post-bag."

"You are sure this one was among them?"

"Yes, I observed it."

"How many letters did your Grace write that day?"

"Twenty or thirty. I have a large correspondence. But surely this is
somewhat irrelevant?"

"Not entirely," said Holmes.

"For my own part," the Duke continued, "I have advised the police to
turn their attention to the south of France. I have already said that I
do not believe that the Duchess would encourage so monstrous an action,
but the lad had the most wrong-headed opinions, and it is possible that
he may have fled to her, aided and abetted by this German. I think, Dr.
Huxtable, that we will now return to the Hall."

I could see that there were other questions which Holmes would have
wished to put, but the nobleman's abrupt manner showed that the
interview was at an end. It was evident that to his intensely
aristocratic nature this discussion of his intimate family affairs
with a stranger was most abhorrent, and that he feared lest every
fresh question would throw a fiercer light into the discreetly shadowed
corners of his ducal history.

When the nobleman and his secretary had left, my friend flung himself at
once with characteristic eagerness into the investigation.

The boy's chamber was carefully examined, and yielded nothing save the
absolute conviction that it was only through the window that he could
have escaped. The German master's room and effects gave no further clue.
In his case a trailer of ivy had given way under his weight, and we saw
by the light of a lantern the mark on the lawn where his heels had come
down. That one dint in the short, green grass was the only material
witness left of this inexplicable nocturnal flight.

Sherlock Holmes left the house alone, and only returned after eleven.
He had obtained a large ordnance map of the neighbourhood, and this
he brought into my room, where