No one prompted me any more. It was so still you might have heard a pin drop. The Professor fixed his grey eyes on me, bright with a malignant joy; the Government Inspector was making notes on a piece of paper. Suddenly the latter respectable personage cleared his throat, and Professor Roveni said in his most insinuating manner, “Well?”

I did not reply.

Instead of at once sending me about my business, the Professor wished to imitate the cat which plays with the mouse before tearing it to pieces.

“How?” he added. “Perhaps you are seeking a new solution. I do not say that such may not be found, but we shall be quite satisfied with one of the old ones. Go on. Have you forgotten that you ought to produce the two sides, DE, MF, till they meet? Produce them—go on!”

I obeyed mechanically. The figure seemed to attain a gigantic size, and weighed on my chest like a block of stone.

“Put a letter at the point where they meet—an N. So. And now?”

I remained silent.

“Don’t you think it necessary to draw a line down from N through A to the base of the square, BHIC?”

I thought nothing of the kind; however, I obeyed.

“Now you will have to produce the two sides, BH and IC.”