I bowed the responsibility on to her shoulders with a smile. “I think you should tell us beforehand how you found out—what you did. I’d like to know myself.”
“I was going to. People, you remember the other day, Mr. Bannerlee went on the hilltops again, and he was so taken with the view of distant mountains that he drew sighting lines on his map to show which ones were visible. The sighting lines, of course, were drawn from the same spot, and that spot was on Whimble. After orienting his map, he squinted across it, looking toward the Malvern Hills and the Black Mountain and elsewhere to establish lines of vision. He could even see to Plinlimon; that’s about thirty miles away. You did see Plinlimon that day, didn’t you?”
“Certainly.”
“Well, that was how I knew you hadn’t been on Whimble, whose highest point has an elevation of about 1950 feet. The highest point on Plinlimon is less than 2500. Thirty miles apart and only five hundred feet difference. Now, if Mr. Bannerlee stood anywhere on Whimble and he looked toward Plinlimon, Great Rhos, just across the Vale, would be between him and the mountain. Great Rhos is a flattish sort of hill, and its elevation is 2166. Think that over.”
“How idiotically, infernally stupid of me!” I cried.
“But I don’t see—” said Eve Bartholomew blankly.
Others about the table uttered exclamations that showed their understanding or betrayed their confusion.
The American girl turned to Mrs. Bartholomew. “You see, dear, if you were nineteen feet high and wanted to see something ten yards away that was five feet higher than you, you couldn’t do it if there was a wall a foot higher than you less than a yard away.”
To give her credit, Mrs. Bartholomew grasped the point instantly. But she still was dubious. “Then how did Mr. Bannerlee see the mountain?”
“He must have been somewhere else.”