About here." He tapped the centre of his forehead with his swollen gauntlet.
His companion poised himself for a moment, and then, lashing out with his left hand, came home with a heavy thud on the place indicated.
Dimsdale smiled gently and shook his head.
"It won't do," he said.
"I hit my hardest," the other answered apologetically.
"It won't do.

Try again." The visitor repeated the blow with all the force that he could command.
Dimsdale shook his head again despondently.

"You don't seem to catch it," he said.

"It's like this." He leaned forward, there was the sound of a sharp clip, and the novice shot across the room with a force that nearly sent his skull through the panel of the door.
"That's it," said Dimsdale mildly.
"Oh, it is, is it ?" the other responded, rubbing his head.
"It's deucedly interesting, but I think I would understand it better if I saw you do it to some one else.

It is something between the explosion of a powder magazine and a natural convulsion." His instructor smiled grimly.