“I wonder what speech I shall make next to drive you away, Mr Walton.”

“I am not so easily got rid of, Mr Stoddart,” I answered.  “And as for taking offence, I don’t like it, and therefore I never take it.  But tell me what you are doing now.”

“I have been working for some time at an attempt after a perpetual motion, but, I must confess, more from a metaphysical or logical point of view than a mechanical one.”

Here he took a drawing from a shelf, explanatory of his plan.

“You see,” he said, “here is a top made of platinum, the heaviest of metals, except iridium—­which it would be impossible to procure enough of, and which would be difficult to work into the proper shape.  It is surrounded you will observe, by an air-tight receiver, communicating by this tube with a powerful air-pump.  The plate upon which the point of the top rests and revolves is a diamond; and I ought to have mentioned that the peg of the top is a diamond likewise.  This is, of course, for the sake of reducing the friction.  By this apparatus communicating with the top, through the receiver, I set the top in motion—­after exhausting the air as far as possible.  Still there is the difficulty of the friction of the diamond point upon the diamond plate, which must ultimately occasion repose.  To obviate this, I have constructed here, underneath, a small steam-engine which shall cause the diamond plate to revolve at precisely the same rate of speed as the top itself.  This, of course, will prevent all friction.”

“Not that with the unavoidable remnant of air, however,” I ventured to suggest.

“That is just my weak point,” he answered.  “But that will be so very small!”

“Yes; but enough to deprive the top of perpetual motion.”

“But suppose I could get over that difficulty, would the contrivance have a right to the name of a perpetual motion?  For you observe that the steam-engine below would not be the cause of the motion.  That comes from above, here, and is withdrawn, finally withdrawn.”

“I understand perfectly,” I answered.  “At least, I think I do.  But I return the question to you:  Is a motion which, although not caused, is enabled by another motion, worthy of the name of a perpetual motion; seeing the perpetuity of motion has not to do merely with time, but with the indwelling of self-generative power—­renewing itself constantly with the process of exhaustion?”

He threw down his file on the bench.

“I fear you are right,” he said.  “But you will allow it would have made a very pretty machine.”

“Pretty, I will allow,” I answered, “as distinguished from beautiful.  For I can never dissociate beauty from use.”

“You say that! with all the poetic things you say in your sermons!  For I am a sharp listener, and none the less such that you do not see me.  I have a loophole for seeing you.  And I flatter myself, therefore, I am the only person in the congregation on a level with you in respect of balancing advantages.  I cannot contradict you, and you cannot address me.”