Presently I had the misfortune to hit my elbow against the mattress.

A knock at the door.

"Who is there?" I cry.

"Can I get you any thing, sir? I hope you are not ill," says a voice which I recognize as that of my landlady.

"No, why?"

"I thought you knocked, sir."

"No. Oh! I knocked my elbow against the mattress."

"Ah! that's it. I beg your pardon."

I shall be well attended here, at all events.