“‘Tell the truth,’ I said.  ’Haven’t you suspected something, now and again?  You needn’t be afraid to tell me.’

“‘Well,’ he answered slowly, ’I’ll admit I’ve thought Father a little—­a little strange, perhaps, at times.  But I’ve always tried to think I was mistaken.  I’ve always hoped no one else would see it.  You see, I’m very fond of the old guvnor.’

“I nodded.

“‘Quite right, too,’ I said.  ’There’s not the least need to make any kind of scandal about this.  We must do something, though, but in a quiet way.  No fuss, you know.  I should go and have a chat with your father, and tell him we’ve found out about this thing.’  I touched the divided post.

“Young Jarnock seemed very grateful for my advice and after shaking my hand pretty hard, took my key, and let himself out of the Chapel.  He came back in about an hour, looking rather upset.  He told me that my conclusions were perfectly correct.  It was Sir Alfred Jarnock who had set the trap, both on the night that the butler was nearly killed, and on the past night.  Indeed, it seemed that the old gentleman had set it every night for many years.  He had learnt of its existence from an old manuscript book in the Castle library.  It had been planned and used in an earlier age as a protection for the gold vessels of the ritual, which were, it seemed, kept in a hidden recess at the back of the altar.

“This recess Sir Alfred Jarnock had utilized, secretly, to store his wife’s jewelry.  She had died some twelve years back, and the young man told me that his father had never seemed quite himself since.

“I mentioned to young Jarnock how puzzled I was that the trap had been set before the service, on the night that the butler was struck; for, if I understood him aright, his father had been in the habit of setting the trap late every night and unsetting it each morning before anyone entered the Chapel.  He replied that his father, in a fit of temporary forgetfulness (natural enough in his neurotic condition), must have set it too early and hence what had so nearly proved a tragedy.

“That is about all there is to tell.  The old man is not (so far as I could learn), really insane in the popularly accepted sense of the word.  He is extremely neurotic and has developed into a hypochondriac, the whole condition probably brought about by the shock and sorrow resultant on the death of his wife, leading to years of sad broodings and to overmuch of his own company and thoughts.  Indeed, young Jarnock told me that his father would sometimes pray for hours together, alone in the Chapel.”  Carnacki made an end of speaking and leant forward for a spill.

“But you’ve never told us just how you discovered the secret of the divided post and all that,” I said, speaking for the four of us.

“Oh, that!” replied Carnacki, puffing vigorously at his pipe.  “I found—­on comparing the—­photos, that the one—­taken in the—­daytime, showed a thicker left-hand gatepost, than the one taken at night by the flashlight.  That put me on to the track.  I saw at once that there might be some mechanical dodge at the back of the whole queer business and nothing at all of an abnormal nature.  I examined the post and the rest was simple enough, you know.