to hear the promised explanation. He was just finishing the last page when there came a gentle tap at the door, and Polton entered with a satisfied smile on his dry, shrewd-looking face and a small board in his hand.
"Will this do, sir?" he asked.
As he spoke he handed the little board to Thorndyke, who looked at it and passed it to me.
"The very thing, Polton," my friend replied. "Where did you find it? It's of no use for you to pretend that you've made it in about two minutes and a half."
Polton smiled one of his queer crinkly smiles, and remarking that "it didn't take much making," departed much gratified by the compliment.
"What a wonderful old fellow that is, Jervis," Thorndyke observed as his factotum retired. "He took in the idea instantly and seems to have produced the finished article by magic, as the conjurers bring forth rabbits and bowls of goldfish at a moment's notice. I suppose you see what your modus operandi is to be?"
I had gathered a clue from the little appliance—a plate of white fret-wood about seven inches by five, to one corner of which a pocket-compass had been fixed with shellac—but was not quite clear as to the details of the method.
"You can read a compass pretty quickly, I think?" Thorndyke said.
"Of course I can. Used we not to sail a yacht together when we were students?"
"To be sure we did; and we will again before
