huge, plain, oblong contrivance that reminded me of the diagram
of a parallelopiped which had caused so much trouble in my solid
geometry at college.

"That's the electric furnace, sir," said Craig to me with an
assumed deference, becoming a college professor explaining things
to the son of a great financier. "You see the electrodes at
either end? When the current is turned on and led through them
into the furnace you can get the most amazing temperatures in the
crucible. The most refractory of chemical compounds can be broken
up by that heat. What is the highest temperature you have
attained, Professor?"

"Something over three thousand degrees Centigrade," replied
Poissan, as he and his assistant busied themselves about the
furnace.

We sat watching him in silence.

"Ah, gentlemen, now I am ready," he exclaimed at length, when
everything was arranged to his satisfaction. "You see, here is a
lump of sugar carbon--pure amorphous carbon: Diamonds, as you
know, are composed of pure carbon crystallised under enormous
pressure. Now, my theory is that if we can combine an enormous
pressure and an enormous heat we can make diamonds artificially.
The problem of pressure is the thing, for here in the furnace we
have the necessary heat. It occurred to me that when molten cast
iron cools it exerts a tremendous pressure. That pressure is what
I use."