“Did he mention to you the theories he had embodied recently in his paper read before the British Association?”
“Certainly he did. It was chiefly of those we spoke.”
“His ideas were somewhat fantastic, were they not?” asked Poirot carelessly.
“Some people have thought so. I do not agree.”
“You consider them practicable?”
“Perfectly practicable. My own line of research has been somewhat similar, though not undertaken with the same end in view. I have been investigating the gamma rays emitted by the substance usually known as Radium C, a product of Radium emanation, and in doing so I have come across some very interesting magnetical phenomena. Indeed, I have a theory as to the actual nature of the force we call magnetism, but it is not yet time for my discoveries to be given to the world. Mr. Halliday’s experiments and views were exceedingly interesting to me.”
Poirot nodded. Then he asked a question which surprised me.
“Madame, where did you converse on these topics? In here?”
“No, monsieur. In the laboratory.”
“May I see it?”
“Certainly.”
She led the way to the door from which she had entered. It opened on a small passage. We passed through two doors and found ourselves in the big laboratory, with its array of beakers and crucibles and a hundred appliances of which I did not even know the names. There were two