The professor produced an electric torch and held it up to show that the gap between the stone and the ceiling was unbroken at any point. Then he counted the jewels on the lower edge. Chick made out twenty-four. Three were missing from their sockets—all told, then, there should have been twenty-seven.
The doctor noted the positions of the three empty sockets and, drawing a tapeline from his pocket, proceeded to measure the distances from each of the three—they were widely separated round the circle—from each other. Then he turned to Chick and Harry.
“Do you know where we are?”
“Under the Spot of Life,” it was easy to answer.
“You are in San Francisco!”
“Not in—in—” Chick hesitated.
“Yes. Exactly. This is 288 Chatterton Place—the house of the Blind Spot.” He paused for them to digest this. Then, “Harry—did you say Hobart Fenton was with you on that last night?”
“Hobart and his sister, Charlotte. I remember their coming at the last minute. They were too late, sir.”
The professor nodded.
“Well, Harry, the chances are that Hobart is not more than twenty feet away at the present moment. Charlotte may be sitting right there”—pointing to a spot at Harry's side—“this very instant. And there may be many others.