“I will tell you exactly what to do, if you will do it.”

“Well, I’m bound to say I’ve always found you had reason behind all your queer ways.  I’ll do what you advise.”

“And you, Mr. White Mason?”

The country detective looked helplessly from one to the other.  Holmes and his methods were new to him.  “Well, if it is good enough for the inspector, it is good enough for me,” he said at last.

“Capital!” said Holmes.  “Well, then, I should recommend a nice, cheery country walk for both of you.  They tell me that the views from Birlstone Ridge over the Weald are very remarkable.  No doubt lunch could be got at some suitable hostelry; though my ignorance of the country prevents me from recommending one.  In the evening, tired but happy—­”

“Man, this is getting past a joke!” cried MacDonald, rising angrily from his chair.

“Well, well, spend the day as you like,” said Holmes, patting him cheerfully upon the shoulder.  “Do what you like and go where you will, but meet me here before dusk without fail—­without fail, Mr. Mac.”

“That sounds more like sanity.”

“All of it was excellent advice; but I don’t insist, so long as you are here when I need you.  But now, before we part, I want you to write a note to Mr. Barker.”

“Well?”

“I’ll dictate it, if you like.  Ready?

“Dear Sir: 

“It has struck me that it is our duty to drain the moat, in the hope that we may find some—­”

“It’s impossible,” said the inspector.  “I’ve made inquiry.”

“Tut, tut!  My dear sir, please do what I ask you.”

“Well, go on.”

“—­in the hope that we may find something which may bear upon our investigation.  I have made arrangements, and the workmen will be at work early to-morrow morning diverting the stream—­”

“Impossible!”

“—­diverting the stream; so I thought it best to explain matters beforehand.

“Now sign that, and send it by hand about four o’clock.  At that hour we shall meet again in this room.  Until then we may each do what we like; for I can assure you that this inquiry has come to a definite pause.”

Evening was drawing in when we reassembled.  Holmes was very serious in his manner, myself curious, and the detectives obviously critical and annoyed.

“Well, gentlemen,” said my friend gravely, “I am asking you now to put everything to the test with me, and you will judge for yourselves whether the observations I have made justify the conclusions to which I have come.  It is a chill evening, and I do not know how long our expedition may last; so I beg that you will wear your warmest coats.  It is of the first importance that we should be in our places before it grows dark; so with your permission we shall get started at once.”

We passed along the outer bounds of the Manor House park until we came to a place where there was a gap in the rails which fenced it.  Through this we slipped, and then in the gathering gloom we followed Holmes until we had reached a shrubbery which lies nearly opposite to the main door and the drawbridge.  The latter had not been raised.  Holmes crouched down behind the screen of laurels, and we all three followed his example.