‘According to the father of the learned doctor Niebuhr,* whose recent loss we regret, as you no doubt know, the average speed of these admirable animals is seven thousand geometric paces per hour. Our degenerate donkeys today give you no idea what this proud, indomitable beast is like. He carries himself lightly, is lively and intelligent, subtle, graceful, and moves in a most charming manner! He is the zoological king of the Orient. Turkish and Persian superstitions even attribute a mysterious origin to him, and the name Solomon occurs frequently in stories told about the prowess attributed to these noble creatures by the storytellers of Tibet and Tartary.
‘In short, a tame onager is worth an immense amount of money; it is almost impossible to capture him in the mountains, where he leaps around like a chamois and seems to fly like a bird. The fable of the winged horse, our Pegasus, no doubt has its origins in that country, where shepherds will often have seen an onager leaping from rock to rock. Saddle-donkeys, obtained in Persia by the coupling of a female donkey with a tame onager, are painted red, according to a time-honoured tradition. This usage perhaps gave rise to the saying, “Vicious as a red donkey”. At a time when natural history was much neglected in France, some traveller must have brought back one of these curious animals, which never take kindly to being kept in captivity. The saying must stem from that.
‘The skin you have here’, the scientist went on, ‘is the skin of a wild ass. The origin of the name is disputed. Some claim chagri* is a Turkish word, others say Chagri is the town where this animal’s hide is subjected to a chemical process rather well described by Pallas, and which gives it the particular grain that we admire so much. Monsieur Martellen wrote me that he thinks Châagri is a stream.’
‘Monsieur, I am grateful to you for this information, which would furnish an admirable footnote to Dom Calmet* if the Benedictines still existed. But I have the honour of pointing out to you that this fragment was originally of a size equal to … this map,’ said Raphael, showing Lavrille an open atlas. ‘This last three months it has noticeably contracted …’
‘I see,’ said the naturalist, ‘I understand. Well, Sir, all the skins of creatures of a lower order are subject to a natural wear and tear, easy to conceive of, whose progress is influenced by atmospheric conditions. Even metals expand or contract in a way one can observe, for engineers have noticed fairly wide gaps between great stones that were originally held together by iron bars. Science is vast, human life is very short. So we cannot profess to understand all the phenomena of nature.’
‘Monsieur,’ said Raphael, almost embarrassed, ‘Forgive me for asking this question, but are you absolutely sure that this skin will be subject to the ordinary laws of zoology? Can it be stretched?’
‘Yes, of course!’ said Monsieur Lavrille. Then: ‘Oh, devil take the thing,’ he exclaimed as he tried to stretch the talisman. ‘But, sir,’ he continued, ‘if you care to go and see Planchette,* the famous professor of mechanics, he will certainly find a way to work on this skin to soften it and extend it.’
‘Oh, monsieur, you have saved my life.’
Raphael shook hands with the learned zoologist, and rushed off to Planchette’s, leaving the worthy Lavrille in the middle of his laboratory stacked with jars and dried plants. He had unwittingly brought away from this visit all of human science—a taxonomy! The fellow resembled Sancho Panza recounting the story of the goats to Don Quixote.* He passed the time counting animals and numbering them. With one foot in the grave, he scarcely knew a fraction of the immeasurable numbers of the great herd of creatures God had cast into the ocean of the worlds, for some unknown purpose. Raphael was happy. ‘Now I shall be able to bridle my ass,’ he cried. Sterne had said before him: ‘Let us look after our ass if we want to live to a ripe old age.’ But the beast has a mind of its own!
Planchette was a tall, gaunt man, a true poet lost in perpetual contemplation, forever engaged in looking into the bottomless pit of MOTION. Common mortals label them mad, these sublime intellects, these misunderstood souls who live with an admirable disregard for creature comforts and worldly things, smoking a burnt-out cigar for days on end, or arriving in a salon without always having buttoned up all their clothes in the proper buttonholes. One day, after spending an unconscionable time measuring space, or making endless crosses on their graphs, they analyse some natural law and deconstruct it to the simplest of principles. And all at once the crowd admires some machine or clever vehicle whose invention astonishes and humbles us. The modest scientist smiles and says to his admirers, ‘What have I made then? Nothing. Man does not invent a force, he directs it, and all science does is imitate nature.’
Raphael came upon the professor of mechanics standing there like a hanged man fallen from the scaffold onto his feet. Planchette was examining an agate marble rolling upon a sundial, and waiting for it to stop. The poor man had neither decoration nor pension, for he didn’t know how to present his findings. Content to live in the hope of making a discovery, he was thinking not of glory, the world, or himself, but was living in the world of science for science’s sake.
‘How to describe that!’ he cried. ‘Ah monsieur,’ he went on when he caught sight of Raphael, ‘I am at your service. How is your mother? Go in and see my wife.’
‘I could have lived like that,’ thought Raphael, who drew the scientist out of his reverie by asking him how to go about treating the talisman he had just shown him.
‘Even if you were to laugh at my credulity, monsieur,’ the Marquis concluded, ‘I shall not hide anything from you. This skin seems to me to possess a force of resistance against which one can do nothing.’
‘Monsieur,’ said Planchette, ‘society people always treat science in rather a cavalier fashion, they all say more or less what a man of fashion said to Lalande* when he brought some ladies to see him after the eclipse: “Would you be so good as to do that again?” What effect do you want to produce? The purpose of mechanics is to apply or neutralize the laws of motion. As to motion itself, I declare to you in all humility we are unable to define it. That said, we have observed some constant phenomena which regulate the action of solids and fluids. By reproducing the generative causes of these phenomena we can transport bodies, give them a locomotive force in relation to a determined speed, project them, divide them simply or infinitely by either breaking them or reducing them to powder; we can twist them, rotate them, modify them, compress them, dilate them, extend them. This science, monsieur, is based on one single fact. You see this marble,’ he went on. ‘It is here on this stone. But now it is over there. By what name should we call this physically natural and yet, when you think about it, so extraordinary action? Movement, locomotion, displacement? What great hidden vanity lies beneath these words! Is it a solution if you give it a name? And yet all science is there. Our machines use or deconstruct this action, this fact. This slight phenomenon adapted to mass will blow up Paris.*
‘We can increase speed at the expense of force, and force at the expense of speed. But what are force and speed? Our science is unable to explain, as it is unable to create motion. Motion, of whatever kind it may be, is a huge force, and man does not invent forces. Force is one, like motion, the very essence of force. Everything is motion. Thought is motion. Nature is based upon motion. Death is a form of motion whose end we imperfectly understand. If God is eternal, we have to believe He is in eternal motion. God is perhaps motion itself. That is why motion is inexplicable, as He is. Like Him, it is profound, limitless, incomprehensible, intangible. Who has ever touched, understood, measured motion? We feel its effects without seeing them. We can even deny it as we deny God. Where is it? Where is it not? Where does it come from? Where is the law that governs it? Where is its end? It envelops us, presses on us, and eludes us. It is obvious, as a fact is obvious, obscure as is an abstraction, at once the effect and the cause. It needs space, just as we do, but what is space? Only motion reveals it to us. Without motion space is no more than a meaningless word. An insoluble problem, similar to the voi
d, similar to creation, to the infinite, motion confounds human thought and all we understand is that we will never understand it.
‘Between each of the points successively occupied by this marble in space’, the scientist continued, ‘lies an abyss of human reason, an abyss into which Pascal* fell. To act upon the unknown substance which you want to submit to an unknown force, you first have to establish what it is made of. According to its nature, if we strike it, it will either break, or it will resist. If it splits and you do not intend it to, we shall not achieve our desired result. Do we wish to compress it? We must apply a pressure equally to all the component parts of the substance in such a way as to diminish uniformly the space in between them. Do we wish to stretch it? We shall have to try and apply to each molecule an equal centrifugal force. For, unless we observe this law exactly, we shall cause it to tear. There exist, my dear sir, infinite modes and unlimited combinations in motion. What result do you hope to achieve?’
‘Monsieur,’ said Raphael, with some impatience, ‘I want some kind of strong pressure that will stretch this Skin indefinitely …’
‘Since the substance is finite,’ replied the mathematician, ‘it cannot be stretched indefinitely, but compression will necessarily increase the surface area at the expense of the thickness. It will get thinner and thinner till it loses all substance …’
‘If you obtain that result, monsieur,’ Raphael cried, ‘you will make millions.’
‘I should be robbing you of your money,’ replied the professor in the phlegmatic tones of a Dutchman. ‘I’ll prove to you in a trice the existence of a machine in which God himself would be squashed like a fly. It would reduce a man to the state of blotting paper, a man who is booted, spurred, cravatted, hatted, in his gold, his jewels, everything …’
‘What a terrifying machine!’
‘Instead of drowning their children in the river, the Chinese ought to put them to use like this!’ said the professor, not giving a thought to the respect parents ought to show their offspring.
Planchette, wrapped up in his thoughts, took an empty flowerpot with a hole in the bottom, and placed it on the paved slab of the sundial. Then he went to look for some clay in the corner of the garden. Raphael remained entranced, like a child to whom his nurse is telling a fairy story. After putting his clay on the step, Planchette took a pruning-knife out of his pocket, cut two lengths of elder, and began to hollow out the inside, whistling, as though Raphael were not there.
‘These are the components of the machine,’ he said.
With a piece of bent clay piping he attached one of his connecting elder rods to the bottom of the pot, in such a way as to make the hole in the elder fit the hole in the pot. It looked like an enormous pipe. He spread a layer of clay in the shape of a spade on the stone, placed the flowerpot on the widest part, and fixed the elder stick on the portion which represented the handle of the spade. Finally he put a piece of clay on the end of the elder tube, stuck the other hollow branch in it, taking another rod to join it to the horizontal branch, so that air, or any ambient fluid, could circulate through this improvised machine and flow from the opening of the vertical tube through the intermediate canal right into the big empty flowerpot.
‘Monsieur, this admirable machine’, he said to Raphael, in the grave manner of an academician delivering his inaugural lecture, ‘is one of Pascal’s finest achievements.’
‘I don’t follow you.’
The scientist smiled. He went and untied a small bottle from a fruit tree, in which his pharmacist had sent him a liquid for catching ants. He broke off the bottom, made himself a funnel of it, which he carefully fitted into the hole in the hollow branch that he had stuck vertically in the clay, exactly opposite the large receptacle represented by the flowerpot. Then, with a watering-can, he poured into it the necessary amount of water to reach the brim in both the large vase and in the small circular mouthpiece of the elder branch. Raphael was thinking of his wild ass’s skin.
‘Sir,’ said the physicist, ‘even today water is still thought to be an incompressible substance. Do not forget this fundamental principle. And yet it can be compressed—but so minimally that we must discount its contractile quality. You see the surface of the water that has reached the top of the flowerpot?’
‘Yes, sir.’
‘Well, suppose this surface were a thousand times greater than the opening of the elder stick through which I poured the liquid. Now look, I’ll take the funnel out.’
‘I see.’
‘Well, sir, if by some means I increase the volume of this mass by introducing yet more water into the opening of the little tube, the fluid, which has to go down it, will rise in the reservoir represented by the flowerpot until the liquid reaches the same level in both …’
‘That’s obvious,’ cried Raphael.
‘But there is this difference,’ went on the scientist, ‘that if the thin trickle of water added in the small vertical tube exerts a force equal, say, to the weight of a pound, since its action will transmit itself faithfully to the liquid mass and will react on all the points of the surface present in the flowerpot, there will be a thousand columns of water all tending to rise up as if they were impelled by a force equal to the one which makes the liquid descend into the vertical stick of elder, and they will necessarily produce here’, said Planchette showing Raphael the opening of the flowerpot, ‘a force a thousand times stronger than the power introduced there.’
And the scientist pointed to the rod of wood poking out of the clay.
‘It’s very simple,’ said Raphael.
Planchette smiled.
‘In other words,’ he insisted with the logic natural to mathematicians, ‘it would be necessary if we want to stop the water overflowing, to exert, on each part of the large surface, a force equal to the force acting in the vertical conduit. But with this one difference, that if the liquid column is a foot high, the thousand small columns of the large surface will only have a very slight elevation.
‘Now,’ said Planchette, flicking his tubes aside, ‘let us replace this grotesque little machine by metallic tubes of a suitable force and dimension; if you cover the fluid surface of the large reservoir with a large mobile plate, and over this plate you place another one whose resistance and solidity are able to withstand any strain, if moreover you grant me the power to add more water continuously by the small vertical tube to the liquid mass, the object, stuck between two solid surfaces, must of necessity give way to the huge force ceaselessly pressing upon it. Making a continuous flow of water via the small tube is no problem at all in mechanics, nor is the transmission of the force of the liquid mass to a plate. Two pistons and a few valves are all you need. So you can imagine, my dear sir,’ he said, taking Valentin’s arm, ‘that there is scarcely any substance in the world which, placed between two limitless forces, cannot be squeezed out flat.’
‘What! Are you saying the writer of the Lettres provinciales invented …’ cried Raphael.
‘He alone, sir. Mechanics knows nothing more simple or more beautiful. The opposite principle, the power of water to expand, created the steam engine. But water only expands to a certain degree, whereas its incompressibility, being so to speak a negative force, is necessarily infinite.’
‘If this skin expands,’ said Raphael, ‘I promise to raise a gigantic statue to Blaise Pascal, to fund a prize of a hundred thousand francs for the solution of the most engaging problem of mechanics in a decade, to give money for dowries to your female cousins and female cousins once removed, and lastly to build a hospital for mad or indigent mathematicians.’
‘That would be very useful,’ said Planchette. ‘Sir,’ he continued, with the calm of a man living on a completely intellectual plane, ‘tomorrow we will visit Spieghalter.* That distinguished mechanical engineer has just made and perfected, after my design, a machine by which a child could contain a thousand bales of hay in his hat.’
‘Till tomorrow, monsieur.’
‘Till tomorrow.’
‘Let me hear about mechanics!’ cried Raphael. ‘Is that not the finest of all the sciences? That other fellow with his donkeys, classifications, his ducks, his genera, and his jars full of monsters is at the very most good for marking up the scores in a public billiard-hall.’
* * *
The next day a joyful Raphael went to find Planchette and together they went to the Rue de la Santé,* whose name augured well. At Spieghalter’s the young man found himself in an enormous building where a multitude of red-hot, roaring forges met his eyes. It was raining fire, nails flooded the floor, there were oceans of pistons, screws, levers, girders, files, nuts, a sea of castings, wood, valves, and steel bars. The iron filings caught in your throat. There was iron in the air, the men were covered in it, the smell was everywhere; the iron had a life, it was organic, it flowed, walked, had a mind of its own, taking on all manner of shapes, obeying every whim. Through the roaring of the bellows, the crescendo of the hammers, the whistling of the lathes that made the iron groan, Raphael reached a large room, clean and airy, where he could contemplate at leisure the immense press Planchette had talked about. He marvelled at the cast-iron cross-pieces, and the twin plates set on their indestructible axis.
‘If you turned this crank seven times quickly,’ said Spieghalter, showing him a handle in polished steel, ‘you would shatter a steel plate in thousands of pieces which would pierce your legs like needles.’
‘The devil you would,’ cried Raphael.
Planchette himself slipped the skin between the two plates of the all-powerful press, and, full of that confidence that goes with scientific conviction, he worked the handle energetically.