"I want any kind of pressure that is strong enough to expand the skin indefinitely," began Raphael, quite of out patience.
"Substance is finite," the mathematician put in, "and therefore will not admit of indefinite expansion, but pressure will necessarily increase the extent of surface at the expense of the thickness, which will be diminished until the point is reached when the material gives out----""Bring about that result, sir," Raphael cried, "and you will have earned millions.""Then I should rob you of your money," replied the other, phlegmatic as a Dutchman. "I am going to show you, in a word or two, that a machine can be made that is fit to crush Providence itself in pieces like a fly. It would reduce a man to the conditions of a piece of waste paper; a man--boots and spurs, hat and cravat, trinkets and gold, and all----""What a fearful machine!"
"Instead of flinging their brats into the water, the Chinese ought to make them useful in this way," the man of science went on, without reflecting on the regard man has for his progeny.
Quite absorbed by his idea, Planchette took an empty flower-pot, with a hole in the bottom, and put it on the surface of the dial, then he went to look for a little clay in a corner of the garden. Raphael stood spellbound, like a child to whom his nurse is telling some wonderful story. Planchette put the clay down upon the slab, drew a pruning-knife from his pocket, cut two branches from an elder tree, and began to clean them of pith by blowing through them, as if Raphael had not been present.
"There are the rudiments of the apparatus," he said. Then he connected one of the wooden pipes with the bottom of the flower-pot by way of a clay joint, in such a way that the mouth of the elder stem was just under the hole of the flower-pot; you might have compared it to a big tobacco-pipe. He spread a bed of clay over the surface of the slab, in a shovel-shaped mass, set down the flower-pot at the wider end of it, and laid the pipe of the elder stem along the portion which represented the handle of the shovel. Next he put a lump of clay at the end of the elder stem and therein planted the other pipe, in an upright position, forming a second elbow which connected it with the first horizontal pipe in such a manner that the air, or any given fluid in circulation, could flow through this improvised piece of mechanism from the mouth of the vertical tube, along the intermediate passages, and so into the large empty flower-pot.
"This apparatus, sir," he said to Raphael, with all the gravity of an academician pronouncing his initiatory discourse, "is one of the great Pascal's grandest claims upon our admiration.""I don't understand."
The man of science smiled. He went up to a fruit-tree and took down a little phial in which the druggist had sent him some liquid for catching ants; he broke off the bottom and made a funnel of the top, carefully fitting it to the mouth of the vertical hollowed stem that he had set in the clay, and at the opposite end to the great reservoir, represented by the flower-pot. Next, by means of a watering-pot, he poured in sufficient water to rise to the same level in the large vessel and in the tiny circular funnel at the end of the elder stem.
Raphael was thinking of his piece of skin.
"Water is considered to-day, sir, to be an incompressible body," said the mechanician; "never lose sight of that fundamental principle;still it can be compressed, though only so very slightly that we should regard its faculty for contracting as a zero. You see the amount of surface presented by the water at the brim of the flower-pot?"
"Yes, sir."
"Very good; now suppose that that surface is a thousand times larger than the orifice of the elder stem through which I poured the liquid.
Here, I am taking the funnel away----"
"Granted."
"Well, then, if by any method whatever I increase the volume of that quantity of water by pouring in yet more through the mouth of the little tube; the water thus compelled to flow downwards would rise in the reservoir, represented by the flower-pot, until it reached the same level at either end.""That is quite clear," cried Raphael.
"But there is this difference," the other went on. "Suppose that the thin column of water poured into the little vertical tube there exerts a force equal, say, to a pound weight, for instance, its action will be punctually communicated to the great body of the liquid, and will be transmitted to every part of the surface represented by the water in the flower-pot so that at the surface there will be a thousand columns of water, every one pressing upwards as if they were impelled by a force equal to that which compels the liquid to descend in the vertical tube; and of necessity they reproduce here," said Planchette, indicating to Raphael the top of the flower-pot, "the force introduced over there, a thousand-fold," and the man of science pointed out to the marquis the upright wooden pipe set in the clay.
"That is quite simple," said Raphael.
Planchette smiled again.
"In other words," he went on, with the mathematician's natural stubborn propensity for logic, "in order to resist the force of the incoming water, it would be necessary to exert, upon every part of the large surface, a force equal to that brought into action in the vertical column, but with this difference--if the column of liquid is a foot in height, the thousand little columns of the wide surface will only have a very slight elevating power.
