His eye, which had been turned inward during his reverie, dullish and somewhat fish-like, now sparkled like a hot coal, and he led the way eagerly.

“Pray humor him, sir,” said Bayne, compassionately.

They followed him up a horrid stair, and entered his studio and a marvelous place it was:  a forge on one side, a carpenter’s bench and turning-lathe on the other and the floor so crowded with models, castings, and that profusion of new ideas in material form which housewives call litter, that the artist had been obliged to cut three little ramified paths, a foot wide, and so meander about the room, as struggles a wasp over spilt glue.

He gave the doctor the one chair, and wriggled down a path after pencil and paper:  he jumped with them, like a cat with a mouse, on to the carpenter’s bench, and was soon absorbed in drawing.

When he had drawn a bit, he tore up the paper, and said, “Let me think.”

“The request is unusual,” said Dr. Amboyne; “however, if you will let us smoke, we will let you think.”

No reply from the inventor, whose eye was already turned inward, and fish-like again.

Dr. Amboyne and Bayne smoked peaceably awhile.  But presently the inventor uttered a kind of shout.

“Eureka,” said the doctor calmly, and emitted a curly cloud.

Little dashed at the paper, and soon produced a drawing.  It represented two grindstones set apparently to grind each other, a large one below, a small one above.

“There—­the large stone shall revolve rapidly, say from north to south; the small one from south to north:  that is the idea which has just struck me, and completes the invention.  It is to be worked, not by one grinder, but two.  A stands south, and passes the saw northward between the two grindstones to B. The stones must be hung so as just to allow the passage of the saw.  B draws it out, and reverses it, and passes it back to A. Those two journeys of the saw will grind the whole length of it for a breath of two or three inches, and all in forty seconds.  Now do you see what I meant by the grammar of mechanics?  It was the false grammar of those duffers, grinding a long thing sideways instead of lengthways, that struck my mind first.  And now see what one gets to at last if one starts from grammar.  By this machine two men can easily grind as many big saws as twenty men could grind on single stones:  and instead of all that heavy, coarse labor, and dirt, and splashing, my two men shall do the work as quietly and as easily as two printers, one feeding a machine with paper, and his mate drawing out the printed sheet at the other end.”

“By Jove,” said Dr. Amboyne, “I believe this is a great idea.  What do you say, Mr. Bayne?”

“Well, sir, a servant mustn’t always say his mind.”

“Servant be hanged!” said Little.  “That for a friend who does not speak his mind.”

“Well, then, gentlemen, it is the most simple and beautiful contrivance I ever saw.  And there’s only one thing to be done with it.”