"Well, that's what Professor Dove used them for; to mystify his dupes; or, by the looks of him, it's more than likely that he believed in them himself."
"Hudson must have believed in them too, then," she remarked, "or he wouldn't have been keeping them in his desk drawer. Was he a dupe, do you think?"
"You'll recall that Hudson had several of them in his possession. If he had had only one, I'd say he might have been a dupe."
"But what if he did have several?" queried Valeska. "Do you think Hudson murdered the professor?"
"Ah, my dear, that's what I'd like to know myself. I propose that we call at the Vibratory office, or whatever they call it. You see, I doubt if Professor Dove ever had six thousand dollars, or even six thousand cents; he was not worth murdering for his money. One thing is certain, Hudson didn't murder Miss Vivian; and I'm glad of that, for I'd really like to see her. Suppose we go up to Thirty-ninth Street and find out what sort of place it is."
As they walked across town the Master of Mysteries said, "That's a very clever graft, that vibration curve business. The more I think of it, the more I like it. You see, as there are two adjustments, the length of the upper and the length of the lower pendulum, you can get an infinite number of vibrations, and consequently an infinite number of curves. Therefore, you can attach any significance you please to the ratio between the two. Suppose, for instance, you divide off the top arm that corresponds to the upper part of the Y into inches, and call each inch a certain year. Then divide the lower arm in a similar way into days; say these are eighths of an inch each. If you set your com-
