Page:The achievements of Luther Trant - Balmer and MacHarg - 1910.djvu/194

168 sheet above the other two and wired electrically to a key like that of a telegraph instrument fastened to the table. When this key was in its normal position this pencil made simply a straight line upon the sheet; but instantly when the key was pressed down, the line broke downward also.

This third instrument was used merely to record on the sheet, by the change in the line, the point at which the object that aroused sensation or emotion was displayed to the person undergoing examination.

The instant's silence which followed Schmalz's rapid explanation was broken by one of Welter's companions with the query:

"Well, what's the use of all this stuff, anyway?"

"Ach!" said Schmalz, bluntly, "it is interesting, curious! I will show you."

"Will one of you gentlemen," said Trant, quickly, "permit us to make use of him in the demonstration?"

"Try it, Jim," Welter laughed, noisily.

"Not I," said the other. "This is your circus."

"Yes, indeed it's mine. And I'm not afraid of it. Schmalz, do your worst!" He dropped laughing into the chair the professor set for him, and at Schmalz's direction unbuttoned his vest. The professor hung the pneumograph around his neck and fastened it tightly about the big chest. He laid Welter's forearm in a rest suspended from the ceiling, and attached the cylinder to the second finger of the plump hand. In the meantime Trant had quickly set the pencils to bear upon the record sheet and had started the cylinder on which the sheet traveled under them.