"That I can understand," I replied, and then a ray of light broke upon me. "Had not Cavendish demonstrated that, when a small ball of lead is suspended on a film of silk, near a mass of iron or lead, it is drawn towards the greater body? We will be drawn by gravity to the nearest cliff," I cried.
"You mistake," he answered; "Cavendish performed his experiments on the surface of the earth, and there gravity is always ready to start an object into motion. Here objects have no weight, and neither attract nor repel each other. The force of cohesion holds together substances that are in contact, but as gravitation can not now affect matter out of molecular contact with other forms of matter, because of the equilibrium of all objects, so it may be likewise said, that bodies out of contact have at this point no attraction for one another. If they possessed this attribute, long ago we would have been drawn towards the earth cliff with inconceivable velocity. However, if by any method our bodies should receive an impulse sufficient to start them into motion, ever so gently though it be, we in like manner would continue to move in this frictionless medium—until"—
"We would strike the material boundary of this crevice," I interrupted.
"Yes; but can you conceive of any method by which such voluntary motion can now be acquired?"
"No."
"Does it not seem to you," he continued, "that when skillful mechanics on the earth's surface are able to adjust balances so delicately that in the face of friction of metal, friction of air, inertia of mass, the thousandth part of a grain can produce motion of the great beams and pans of such balances, we, in this location where there is no friction and no opposing medium—none at all—should be able to induce mass motion?"
"I can not imagine how it is possible, unless we shove each other apart. There is no other object to push against,—but why do you continue to hold me so tightly?" I interrupted myself to ask, for he was clasping me firmly again.
"In order that you may not leave me," he replied.
"Come, you trifle," I said somewhat irritated; "you have just argued that we are immovably suspended in a frictionless medium, and fixed in our present position; you ask me to suggest some method by which we can create motion, and I fail to devise it, and almost in the same sentence you say that you fear that I will leave you. Cease your incongruities, and advise with me rationally."
"Where is the bar of iron?" he asked.