"Oh, sir," he laughed, "that's Mad 'Arry. 'E's quite 'armless. 'E's
out most nights, but we never see 'im in the day, poor chap. I've
known 'im ever since he was about nine."

"Does no work, I suppose?"

"None. 'Ow can 'e? 'E's as mad as a hatter, as the sayin' goes,"
replied the constable, his thumbs hitched in his belt as he stood.

"A kind of midnight wanderer, eh?"

"Yes, 'e's always a-pryin' about at night. Not long ago 'e found
burglars in a 'ouse in Gloucester Terrace, and gave us the alarm. We
copped four of 'em. The magistrate gave 'im a guinea out o' the
poor-box."

"Ah! so he's of use to you?"

"Yes, sir, 'e's most intelligent where there's any suspicious
characters about. I've often put 'im on the watch myself."

"Then he's not quite insane?"

"Not on that point, at any rate," laughed the officer.

"Where does he live?"

"'Is father's a hackney-carriage driver, and 'e lives with 'im up in
Gloucester Mews, just at the back of Porchester Mews--I don't know if
you know it?"

I was compelled to confess ignorance of the locality, but he directed
me.

"Are you on night-duty in Porchester Terrace, constable?" I asked a
few moments later.

"Yes, sir, sometimes. Why?"

"You know Althorp House, of course?"

"Yes, the 'aunted 'ouse, as some people call it. Myself, I don't
believe in ghosts."

"Neither do I," I laughed, "but I've heard many funny stories about
that place. Have you ever heard any?"

"Lots, sir," replied the man. "We're always being told of strange
things that 'ave 'appened there, yet when we 'ave a look around we
never find anything, so we've ceased to trouble. Our inspector's
given us orders not to make any further inquiries, 'e's been worried
too often over idle gossip."

"What's the latest story afloat concerning the place?" I asked. "I'm
always interested in mysteries of that sort."

"Oh, I 'eard yesterday that somebody was seen to get out of a taxi-cab
and enter. And 'e 'asn't been seen to come forth again."

"That's curious," I said. "And haven't you looked over the place?"

"I'm not on duty there. Perhaps my mate 'as. I don't know.
But, funnily enough," added the officer, "Mad 'Arry has been
tellin' me something about it a moment ago--something I can't
understand--something about the garden. I suppose 'e's been a-fancyin'
something or other. Everybody seems to see something in the garden, or
at the windows. Why, about a week ago, a servant from one of the
'ouses i