“Ah!”

“He forged elementary effects ...”

“You can’t but admit that.”

“I don’t attempt to deny it.  But, as he explained, the thing is necessary—­justifiable.  Psychic phenomena are subtle, a certain training of the observation is necessary.  A medium is a more subtle instrument than a balance or a borax bead, and see how long it is before you can get assured results with a borax bead!  In the elementary class, in the introductory phase, conditions are too crude....”

“For honesty.”

“Wait a moment. Is it dishonest—­rigging a demonstration?”

“Of course it is.”

“Your professors do it.”

“I deny that in toto,” said Smithers, and repeated with satisfaction, “in toto.”

“That’s all right,” said Lagune, “because I have the facts.  Your chemical lecturers—­you may go downstairs now and ask, if you disbelieve me—­always cheat over the indestructibility of matter experiment—­always.  And then another—­a physiography thing.  You know the experiment I mean?  To demonstrate the existence of the earth’s rotation.  They use—­they use—­”

“Foucault’s pendulum,” said Lewisham.  “They use a rubber ball with a pin-hole hidden in the hand, and blow the pendulum round the way it ought to go.”

“But that’s different,” said Smithers.

“Wait a moment,” said Lagune, and produced a piece of folded printed paper from his pocket.  “Here is a review from Nature of the work of no less a person than Professor Greenhill.  And see—­a convenient pin is introduced in the apparatus for the demonstration of virtual velocities!  Read it—­if you doubt me.  I suppose you doubt me.”

Smithers abruptly abandoned his position of denial “in toto.”  “This isn’t my point, Mr. Lagune; this isn’t my point,” he said.  “These things that are done in the lecture theatre are not to prove facts, but to give ideas.”

“So was my demonstration,” said Lagune.

“We didn’t understand it in that light.”

“Nor does the ordinary person who goes to Science lectures understand it in that light.  He is comforted by the thought that he is seeing things with his own eyes.”

“Well, I don’t care,” said Smithers; “two wrongs don’t make a right.  To rig demonstrations is wrong.”

“There I agree with you.  I have spoken plainly with this man Chaffery.  He’s not a full-blown professor, you know, a highly salaried ornament of the rock of truth like your demonstration-rigging professors here, and so I can speak plainly to him without offence.  He takes quite the view they would take.  But I am more rigorous.  I insist that there shall be no more of this....”

“Next time—­” said Smithers with irony.

“There will be no next time.  I have done with elementary exhibitions.  You must take the word of the trained observer—­just as you do in the matter of chemical analysis.”

“Do you mean you are going on with that chap when he’s been caught cheating under your very nose?”