“The delay is unnecessary.”

“I am certain I can provide a mine within two days,” insisted Mr. Johnson. “Suppose we set the next test for Thursday night at this same hour?”

Thus trapped, Professor Bettenridge could not refuse without losing the sale. Scowling, he gave in.

“Very well. But this will be the final demonstration. If you are not satisfied Thursday night, the deal is off.”

“Agreed,” said Mr. Johnson.

Bowing to the Bettenridges, he departed. Others who had witnessed the demonstration began to melt away. Only Salt and Penny remained.

Professor Bettenridge closed the door so that the conversation would not be overheard. Then he turned angrily to the pair.

“Now what’s your little game?” he demanded. “You deliberately tried to queer my sale? Why?”

“Mr. Johnson seems like such an innocent little rabbit, maybe we thought he ought to be protected,” Salt drawled.

“Protected! Why, he’s being given the opportunity of a lifetime! How much is it worth to you to keep out of my affairs?”