“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?”