"Of course, Holmes maintained it was all an accident,” I remarked to Lestrade. We were enjoying a relaxing pint together one evening.
“What exactly happened?” Lestrade enquired.
“Holmes was experimenting with two magnifying glasses, to see whether they would reveal the soil traces he was looking for in the Llewellyn case. You may not have come across it; it was one of Bradstreet’s.”
“And did it?”
“We shall never know. Having set up his equipment, Holmes paused to read something in one of his commonplace books. The trouble was that it was a bright, sunny day. And the sun shone through one magnifying glass and onto the next one.”
“The first I was aware was when I looked up from my newspaper to complain about the smell from the tobacco Holmes was using. Only the smoke wasn’t rising from a pipe, but from the table, and in fact the tablecloth, which was smouldering. Naturally, I got up to do something about it.”
“Holmes told me not to touch anything, as he had set the equipment up with precision. Having no wish to see our rooms go up in smoke, I ignored his instruction and hurriedly extinguished the fire. Then, on hearing Mrs Hudson’s footsteps coming upstairs, I hastily departed. The last I heard was Holmes being loudly berated.”