little appliance that will, I think, solve our difficulty, and I will
show you how I propose that you should make your observations. First of
all, we have to rule the pages of this book into columns."

He sat down at the table and began methodically to rule the pages each
into three columns, two quite narrow and one broad. The process occupied
some time, during which I sat and watched with impatient curiosity the
unhurried, precise movements of Thorndyke's pencil, all agog 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?"