"Hallo, Polton!" I exclaimed, "have you contrived to tear yourself away from the laboratory for an hour or two?"
"No, sir," he answered gloomily. "The laboratory has torn itself away from me."
"What do you mean?" I asked.
"The Doctor has shut himself in and locked the door, and he says I am not to disturb him. It will be a cold lunch to-day."
"What is he doing in there?" I inquired.
"Ah!" said Polton, "that's just what I should like to know. I'm fair eaten up with curiosity. He is making some experiments in connection with some of his cases, and when the Doctor locks himself in to make experiments, something interesting generally follows. I should like to know what it is this time."
"I suppose there is a keyhole in the laboratory door?" I suggested, with a grin.
"Sir!" he exclaimed indignantly. "Dr. Jervis, I am surprised at you." Then, perceiving my facetious intent, he smiled also and added: "But there is a keyhole if you'd like to try it, though I'll wager the Doctor would see more of you than you would of him."
"You are mighty secret about your doings, you and the Doctor," I said.
"Yes," he answered. "You see, it's a queer trade this of the Doctor's, and there are some queer secrets in it. Now, for instance, what do you make of this?"