Physics and chemistry did better than geology and biology; their laws and marvels have always harmonized better than a “Nature red in tooth and claw” with a theistic view of the world. Their vitality is suggested near the outset of this period by the efforts of Oliver of Malmesbury to make an airplane; in 1065 his contraption was ready, he soared in it from a high place, and was killed.45

The science of mechanics produced in the thirteenth century a remarkable figure, a Dominican monk who anticipated several basic conceptions of Isaac Newton. Jordanus Nemorarius became the second General of the Dominican Order in 1222; that such a man could do such brilliant work in science bears witness—if Albert and Thomas were not enough—to the intellectual eagerness of the Preaching Friars. In three mathematical treatises rivaling those of Fibonacci in courage and influence, he accepted the Hindu numerals, and advanced algebra by regularly using letters instead of figures for his general formulas. His Elementa super demonstrationem ponderis studied the component of gravity along a trajectory, and laid down a principle now known as the axiom of Jordanus: that which can raise a certain weight to a certain height can raise a weight K times heavier to a height K times less. Another treatise, De ratione ponderis (perhaps by a pupil), analyzed the notion of statical moment—the product of a force into its lever arm—and anticipated modern ideas in the mechanics of the lever and the inclined plane.46 A third treatise, ascribed to “the school of Jordanus,” gave tentative expression to the theory of virtual displacements—a principle developed by Leonardo da Vinci, Descartes, and John Bernoulli, and finally formulated by J. Willard Gibbs in the nineteenth century.

The progress of mechanics slowly affected invention. In 1271 Robert of England clearly stated the theory of the pendulum clock. In 1288 we hear of a great clock in a tower at Westminster, and, about the same time, of similar giants in churches on the Continent; but there is no certain indication that these were fully mechanical. The first clear mention of a clock operated by pulleys, weights, and gears is dated 1320.47

The most successful branch of physics in this period was optics. The Arabic treatises of al-Haitham, translated into Latin, opened almost a new world to the West. In an essay on the rainbow Robert Grosseteste, about 1230, wrote of a

third branch of perspective… untouched and unknown among us until the present time… [which] shows us how to make things very far off seem very close at hand, and how to make large objects which are near seem tiny, and how to make distant objects appear as large as we choose.

These marvels, he adds, can be achieved through breaking up “the visual ray” by passing it through several transparent objects or lenses of varying structure. These ideas fascinated his pupil Roger Bacon. Another Franciscan monk, John Peckham, probably also a pupil of Grosseteste at Oxford, dealt with reflection, refraction, and the structure of the eye in a treatise Perspectiva communis; when we recall that Peckham became Archbishop of Canterbury we perceive again an unsuspected entente between science and the medieval Church.

One result of these studies in optics was the invention of spectacles. Magnifying glasses had been known to Greek antiquity,48 but the construction of such glasses to focus properly when near the eye seems to have awaited research in the geometry of refraction. A Chinese document of uncertain date between 1260 and 1300 speaks of glasses called ai tai, which enabled old people to read fine script. A Dominican friar, preaching at Piacenza in 1305, remarked: “It is not twenty years since there was discovered the art of making eyeglasses [occhiali], which enable one to see well…. I myself have spoken to the man who first discovered and made them.” A letter dated 1289 says: “I am so heavy with years that without the glasses called okiali, recently invented, I should not be able to read or write.” The invention is usually credited to Salvino d’Amarto, whose tombstone, dated 1317, read: “the inventor of spectacles.” In 1305 a Montpellier physician announced that he had prepared an eyewash that made spectacles superfluous.49

The attractive power of the magnet had also been known to the Greeks. Its power to indicate direction was apparently discovered by the Chinese in the first century of our era. Chinese tradition ascribes to Moslems, about 1093, the earliest use of the magnetic needle in guiding navigation. Such use was probably widespread among Moslem and Christian mariners by the end of the twelfth century. The oldest Christian reference to it is in 1205, the oldest Moslem reference is in 1282;50 but perhaps those who had long known the precious secret had been in no haste to publish it. Moreover, mariners who used it were suspected of magic, and some sailors refused to sail with a captain who kept such a demonic instrument.51 The first known description of a pivoted floating compass occurs in an Epistola de magnete by Petrus Peregrinus in 1269. This Peter the Pilgrim recorded many experiments, advocated the experimental method, and expounded the operation of the magnet in attracting iron, magnetizing other objects; and finding the north. He tried also to construct a perpetual motion machine operated by self-regenerating magnets.52

Chemistry advanced largely through alchemical research. From the tenth century onward Arabic texts in this field were translated into Latin, and soon the West steamed with alchemy, even in monasteries. Brother Elias, successor to St. Francis, edited a work on alchemy for Frederick II; another Franciscan, Grosseteste, wrote in favor of the possibility of transmuting metals; and one of the most famous of medieval books, the Liber de causis, presented alchemy and astrology in a work foisted upon Aristotle. Several European kings employed alchemists in the hope of rescuing their treasuries by changing cheap metals into gold.53 Other zealots continued the search for the elixir of life and the philosopher’s stone. In 1307 the Church condemned alchemy as a diabolical art, but its practice continued. Perhaps to escape ecclesiastical censure several authors of the twelfth or thirteenth century attributed their works on alchemy to the Moslem “Gebir.”

Medical experience with drugs added to chemical knowledge, and industrial operations almost compelled experiment or discovery. The brewing of beer, the manufacture of dyes, pottery, enamels, glass, glue, lacquer, ink, and cosmetics contributed to the science of chemistry. Peter of St. Omer, about 1270, composed a Liber de coloribus faciendis, containing recipes for the various pigments used in painting; one recipe described the making of oil colors by mixing the pigment with linseed oil.54 About 1150a treatise known as the Magister Salernus—presumably a product of the Salerno school of medicine—mentioned the distillation of alcohol; this is the first clear reference to that now universal operation. The grape-producing countries distilled wine, and called the result aqua vitae, eau de vie water of life; the North, with less grapes and bitterer cold, found it cheaper to distill grain. The Celtic term uisqebeatha, which was shortened into whisky, also meant “water of life.”55 Distillation had been known long before to Moslem alchemists; but the discovery of alcohol—and, in the thirteenth century, of mineral acids—vastly enlarged chemical knowledge and industry.

Almost as important in its effects as the distillation of alcohol was the discovery of gunpowder. The old Chinese claim to priority here is now challenged; and there is no clear mention of the substance in Arabic manuscripts before 1300.56 The earliest known notice of the explosive is in a Liber ignium ad comburendos hostes, or Book of Fires for Burning Enemies, written by Marcus Graecus, about 1270. After describing Greek fire and phosphorescence Mark the Greek gave a recipe for making gunpowder: reduce to a fine powder, separately, one pound of live sulphur, two pounds of charcoal from the lime or willow tree, and six pounds of saltpeter (potassium nitrate); then mix them.57 There is no record of any military use of gunpowder before the fourteenth century.

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