On the table was an electric instrument like a small clock, and the doctor's first action was to attach to it two wires with small, black rubber mouthpieces.
"Now, Mr. Wardrop," he said, "we will go on with the test. Your other condition is fair, as I told you; I think you can dismiss the idea of insanity without a second thought, but there is something more than brain and body to be considered; in other words, you have been through a storm, and some of your nervous wires are down. Put the mouthpiece between your lips, please; you see, I do the same with mine. And when I give you a word, speak as quickly as possible the association it brings to your mind. For instance, I say 'noise.' Your first association might be 'street,' 'band,' 'drum,' almost anything associated with the word. As quickly as possible, please."
The first few words went simply enough. Wardrop's replies came almost instantly. To "light" he replied "lamp;" "touch" brought the response "hand;" "eat" brought "Burton," and both the doctor and I smiled. Wardrop was intensely serious. Then--
"Taxicab," said the doctor, and, after an almost imperceptible pause, "road" came the association. All at once I began to see the possibilities.
"Head." After a perceptible pause the answer came uncertainly. "Hair." But the association of ideas would not be denied, for in answer to the next word, which was "ice," he gave "blood," evidently following up the previous word "head."
I found myself gripping the arms of my chair. The dial on the doctor's clock-like instrument was measuring the interval; I could see that now. The doctor took a record of every word and its response. Wardrop's eyes were shifting nervously.
"Whisky." "Glass," all in less than a second.
"Pearls." A little hesitation, then "box."
"Traveling-bag." He brought out the word "train" after an evident struggle, but in answer to the next word "lost," instead of the obvious "found," he said "woman." He had not had sufficient mental agility to get away from the association with "bag." The "woman" belonged there.
"Murder" brought "dead," but "shot," following immediately after, brought "staircase."
I think Wardrop was on his guard by that time, but the conscious effort to hide truths that might be damaging made the intervals longer, from that time on. Already I felt sure that Allan Fleming's widow had been right; he had been shot from the locked back staircase. But by whom?