Chapter II: Front Matter (2)

In addition, Leonardo laid before Ludovico all manner of cannons and designs for tunneling under the enemy’s defenses. Actually, with respect to warfare itself, Leonardo called it a most brutal “madness”; however, he recognized the necessity of being prepared. In his notebook, he wrote, “When besieged by ambitious tyrants I find a means of offense and defense in order to preserve the chief gift of nature, which is liberty.”

Ludovico was very much interested in the things Leonardo had showed him. Although he was a man of limited imagination and was not able to grasp the scope of Leonardo’s proposals, he was nevertheless involved in a war. Since Ludovico’s aging military engineer was to be replaced, Leonardo left the forbidding castle of the Sforzas with high hopes of getting the position.

In the meantime, he was commissioned to paint the portrait of a young girl from a noble family in Milan. At the same time, he began the bronze equestrian statue of Ludovico’s father, Francesco Sforza. For this work, he began an intensive study of horses. Since hunting was the popular sport at the court of the Sforzas, Ludovico owned a stable of the finest Arabian horses, and here Leonardo commenced his drawings. Again, his research for a work of art led him beyond just making preparatory sketches. His studies developed into notes, and his notes into a planned book on the anatomy of the horse.

During these months of waiting for the appointment as military engineer, Leonardo furthered his experiments with cannon. In the course of these experiments, he came across a power that would later revolutionize all industry—steam. He devised—although he attributed the original idea to Archimedes—a water vessel connected to a copper tube which was heated by a fire. The water when flowing into the red-hot tube changed into steam and the pressure of the steam blew out a ball at the mouth of the tube with great force. Leonardo experimented with steam in other ways. He built an apparatus for measuring the transformation of water into vapor. It consisted of a metal box in which was a thin animal bladder partly filled with water. Resting on the top of the bladder was a flat lid attached by a cord hung from two pulleys to a counterweight on the outside. As the water was heated, the steam in the bladder pushed up the lid. As the lid rose both the volume and the pressure could be measured. There were distillation experiments with various condensers, one in particular that anticipated the modern condenser of Leibig, introducing double walls that formed a complete jacket for cooling with water in continual circulation.

Not content with having an idle moment, Leonardo again turned to searching out books that he had not read and trying to fill the gaps in his education. He became especially interested in the German philosopher, Cardinal Cusanus. Cusanus, like himself, had been influenced by Toscanelli and was a man devoted to the natural sciences. Leonardo also studied the philosophy of Aristotle and the writings of St. Augustine. Throughout his life Leonardo believed in an active mind for, as “iron rusts from disuse, stagnant water loses its purity and in cold weather becomes frozen, even so does inaction sap the vigor of the mind.”

Unfortunately, the post of military engineer went to a man named Ambrogio Ferrari. The extent and variety of Leonardo’s proposals were too great for Ludovico to trust. He did not believe that one man could possibly bring all those ideas into being. Ferrari, on the other hand, was a military engineer only, and a man who was content with the customary methods of warfare. Furthermore, Ludovico had at last decided that peaceful negotiations would gain him more than fighting. Thus Leonardo’s chance of recognition was again postponed.

Meanwhile, the money that Leonardo had brought with him from Florence was almost gone. He had been forced to move from his apartment to a single room and now he was barely able to live from day to day. Although the court of Ludovico Sforza was one of the richest in the world, artists were frequently treated as servants; often they were the last to be paid for their services. Also, Leonardo was a foreigner in the city, which meant he was regarded with suspicion.

Because of these reasons, Leonardo finally decided to do what the Milanese artists did—they banded together in groups sharing work and costs. Leonardo had met a young artist of twenty-eight, Giovanni Ambrogio de Predis, at the court of Ludovico. Ambrogio was court painter to the Sforza family and had achieved some success. Ambrogio recognized in the handsome stranger from Florence, however, the touch of genius, and he realized that his own talents would be furthered by learning from Leonardo. The two young men decided to pool their abilities. Ambrogio offered both lodging and a studio; and, in association with his two half-brothers, one a woodcarver, another a miniaturist, and his elder brother, a minter of coins, they would not lack for commissions.

Commissions weren’t long in coming. On April 25, 1483, a contract was signed between Bartolommeo degli Scarlione, a prior of the Fraternity of the Immaculate Conception, and Ambrogio and Leonardo for an altarpiece. The fee was two hundred ducats, with a promise of more if it were delivered on time and was satisfactory to the Fraternity. Delivery date was to be December 8, 1484. Ambrogio was to paint the altar wings and Leonardo the center piece—a picture of the Blessed Virgin and Child.

But when the painting was finished, it was not according to the instructions set forth in the contract. Leonardo had too independent a mind to be bound by conformity. Nor was it completed on time. Indeed, for twenty years the quarrel between the Fraternity and the painters went on. After ten years, Ludovico was asked to intervene for the money owed; after he failed, another ten years went by and the King of France himself was finally asked to settle the dispute. Leonardo wanted his one hundred ducats and the Fraternity offered twenty-five. Eventually, a secret agreement was arrived at and the painting was restored to Leonardo and Ambrogio. Leonardo’s painting, the masterpiece entitled the “Virgin of the Rocks,” now hangs in the museum of the Louvre in Paris.

The day this contract was signed, Leonardo walked back through the city to Ambrogio’s studio near the Ticino gate. He was low in spirits from reading the petty instructions of the contract, and, in this mood, he became aware of the city streets and crowds about him. The noise, the confusion, the smells—yes, the smells were the worst. Garbage, filth, and dust were in heaps where the last rainwater had left them and they buzzed with flies.

Moreover the houses were jammed together and shopkeepers crowded their wares to the edges of the streets, leaving just enough room for the occasional horseman to get through. Latrines were only for the better houses; here, the streets, alleys and even open doorways were toilets. People flung their scraps out of the window and at night in the poorly lit streets could be heard the scurrying of rats. Leonardo stopped, thinking half aloud:

“Two levels. Streets running one above the other—one for pedestrians and one for carts and horses. Yes, and cutting through the whole city a system of canals to carry the city’s waste to a river or to the sea. Why not even ten cities of, say, five thousand houses in each—say, no more than thirty thousand people to a city?”

Intent now on his thoughts he hurried to his home, his mind busy with his visions of new cities.

During the years 1484 and 1485 the bubonic plague swept Italy—the same dreaded Black Death so prevalent in medieval times. Milan was one of the cities most severely stricken. Every courtyard became a hospital and the streets were deserted except for the rumbling carts picking up the dead. On the roads from the city were lines of refugees fleeing to the country. Surrounding cities that had not been infected manned their fortress walls as in wartime to keep the fleeing populations out.

Ludovico at first tried to protect Milan from the spread of the disease; then, frightened, he and his court fled. Even the ruler’s official documents had to be “disinfected” by perfume and then held for a period of time before he would allow them near him.

Leonardo, sensing opportunity, drew out his plans for his new cities. Canals running through them were to be used for barges and the underground conduits greatly resembled those of modern sewage systems. Paths were to have gutters for the adequate drainage of the streets. Public toilets were to be installed. Leonardo even had plans for the control of smoke collecting over the city—by sending it up tall chimneys where it was picked up by fans and driven away over the roofs. The widths of the streets were to be in proportion to the heights of the houses—light and air would circulate freely. Two levels would be connected by graceful ramps—the lower level for the commercial traffic and the upper level for the pedestrians. Where stairs were used they were designed so one could ascend or descend without one person seeing the other. Stables were devised so that animals were fed through openings in their mangers and under these were tunnels of flowing water for the removal of waste.

These sweeping plans Leonardo laid before Ludovico when the epidemic had subsided. But Ludovico, once his fear was overcome, brushed them aside as impossible dreams.

So Leonardo returned to the commission for the Fraternity and the designs for the bronze monument of Francesco Sforza. These jobs kept Leonardo from brooding about his rejections.

Often, too, Leonardo worked with Bernardino de Predis, the elder brother of Ambrogio. Bernardino was a minter of coins. As Leonardo watched him at the laborious task of first cutting disks from ingots and then hammering the design into the hot metal, he suggested to Bernardino an easier method, then used in Germany. This was to prepare smooth ribbons of metal of the desired thickness and with a punch, impress the design into the ribbon at the necessary intervals and then, punch out the coin. Leonardo went on to improve this system by designing precise punches for both faces of the coin. A single machine then cut out and stamped the coins, using a falling weight raised by little winches. This machine was later destined for the Vatican mint in Rome.

On March 26, 1485 an event occurred in Milan that was viewed with mingled fear, superstition, curiosity and excitement. There was a total eclipse of the sun. To some, coming as it did so soon after the plague, it was a judgment of God; to others, it was regarded as an omen—a sign for astrologers to use for predicting the future.

But to Leonardo the eclipse was a moment of great scientific importance. At this time in history, the Ptolemaic, or geocentric theory of the universe was the popular belief. This theory taught that the earth is fixed and the sun and moon revolve around it. Leonardo himself had believed this theory for a long time. As he grew older, however, he read and heard discussions of the heliocentric theory. This theory proposed that the sun is fixed and the earth and stars move around it. Now, as he watched the eclipse, his doubts of the Ptolemaic concept were renewed and he resolved to make experiments of his own. The new theory was so daring for his times, however, that it would be many years before he became convinced of its truth.

Later that night, deep in thought over the experience of the day, he noted down his observations of the eclipse and his doubts of the medieval concept of the heavens. The Church believed the earth was the fixed center of the universe. Scholars and scientists supported the belief of Aristotle in the four elements, earth, water, air, and fire—but something was wrong. What were the planets—what was the moon? He picked up his pen and on a clean sheet of paper he wrote, “Make glasses in order to see the moon large.”

6
_The Monument_

During this time, Leonardo had been struggling with the design for the bronze equestrian statue. Drawing after drawing lay scattered on his studio floor. Lately, however, a daring plan for this statue had come to him. It was to be a huge bronze warrior, Francesco Sforza, mounted on a rearing horse. Weighing perhaps a hundred thousand pounds, it was to be cast in sections in five furnaces—a fitting monument to the power of the Sforza family. But there still remained a big problem to be solved: how could he balance the plunging horse and man on just the two rear legs of the horse?

Meanwhile, Leonardo had another problem to work on—a wooden model of the Milan cathedral. He had entered his name with the cathedral authorities as a competitor in the design and construction of the cathedral’s dome. Many architects had been brought in and had failed, partly because of the antagonism of the Milanese workmen to foreign craftsmen, and partly because the committee found it difficult to decide what designs it liked. Leonardo had sent them a letter outlining his own recommendations and had drawn many pages of possible plans. He put forward his knowledge of various building materials, his understanding of classical architecture, and his wish to keep his own ideas in harmony with the Gothic tradition of the cathedral itself. Often he would make a point of walking about the city, observing the different constructions under way and drawing up plans to shorten the labor by mechanical means.

In July of 1487 Leonardo received a payment from the cathedral authorities for the wooden model he had submitted. Still, however, no final decision had been reached. Now, as Leonardo looked at the model in his studio, he felt the urge to improve it further—to make it more perfect. Yet he held his impatience in check and decided he would wait a little longer. Instead, he decided to work on some of his ideas for construction devices. He had already made many drawings, but they could be improved, he thought, and he began to make calculations.

Among these notes and drawings was an improvement on a device for the raising of columns. It was a mobile windlass with a transmission gear for transporting and erecting columns and obelisks. Another device was an earth drill resembling a modern corkscrew with double handle bars. The upper bar, when turned, drilled the screw into the earth while the lower bar—when turned the opposite way—carried the dirt up and out. Also there was a double crane mounted on a circular trolley which carried the dirt of excavation up and then the crane was moved around on its trolley so the dirt could be unloaded in different directions.

Other labor-saving devices that Leonardo designed were an automatic pile driver, the weight of which was raised by a winch and tripped automatically at its height to fall on the piling; a lift for raising iron bells to bell towers; and a machine for boring tree trunks to make pipes for carrying water.

In the fall of 1488, Leonardo was interrupted by a summons from Ludovico, who wanted him to design and build the decorations for the forthcoming marriage of his nephew, young Duke Gian Galeazzo Sforza, to Isabella of Aragon, granddaughter of the King of Naples. He worked on this steadily until the wedding ceremony in February of the following year. When the day arrived, the street from the cathedral to the grim castle was trimmed with flags and banners of the two royal houses. The inner courtyards of the castle were transformed into delicate arbors of laurel boughs. Yet it was the evening’s reception and entertainment which were to be the climax and to them Leonardo had brought all his mechanical skill. However, the announcement of the death of the bride’s mother cut short the celebration and, after the bride and groom had left for Pavia, the wedding party soon dispersed. Disappointed that his decorations had not been fully appreciated, Leonardo returned to his studio and the problem of the monument.

He was still struggling with the problem of balancing the rearing horse. And, indeed, a solution was soon found. By placing a fallen soldier with his arm upraised in protection under the forefeet of the horse, Leonardo could balance the enormous weight and provide for the proper casting of the molten bronze.

Finally, Leonardo made a small wax model of the proposed statue and showed it to Ludovico. The nobleman was impressed by its originality. Most of the ideas contributed by other sculptors were mere variations of what had already been done many times. Also, the other plans called for bronze of not more than two thousand pounds, while Leonardo envisioned a statue fifty times that size! Ludovico awarded the commission to Leonardo.

Leonardo was to work on this commission for ten years and it was destined never to be immortalized in bronze, for reasons that will be explained later. His energies, as usual, were poured into many schemes. Growing out of his work on the monument he planned one book on the subject of casting in bronze and another on the anatomy of the horse. But the one subject, which he began to study in this period and which would occupy the remainder of his life, was the study of human anatomy. So Leonardo, in the midst of all his other activities, wrote in his notes, “On the second day of April 1489 the book entitled _Of the Human Figure_.”

The sources of anatomical study up to Leonardo’s day had been the Greeks—Hippocrates and Galen—and the Arab—Avicenna. Books on this subject were few, and the anatomical diagrams were crude and inaccurate. Galen, for example, had based his studies on the dissection of monkeys. Renaissance anatomists had explained his errors by pointing out that man had probably changed since Galen’s time. The Church had stepped in during the fourteenth century with an edict that was interpreted as a prohibition against dissection of the human body. In Italy, however, there were some dissections. They could only use, for this purpose, the bodies of criminals, slaves, and people of foreign birth. In Florence, anatomy was studied by the artists, and Leonardo had undoubtedly watched Pollaiuolo at work on a corpse that that artist had dissected.

In 1489 Leonardo, from the results of his own investigation, produced drawings of the skull and backbone whose careful attention to detail are—even today—classics in art and anatomy. With infinite patience and with a saw of his own invention he had halved a skull and drew for the first time with accuracy the curves of the frontal and sphenoid bones. He drew the lachrymal (tear) canal, and he was the first to show the cavity in the superior maxillary bone—not discovered again until 1651, by Highmore—now named “the antrum of Highmore.” He was the first to demonstrate the double curvature of the spine and its accompanying vertebrae, the inclination of the sacrum, the shape of the rib cage, and the true position of the pelvis. He planned a whole series of books that would include from head to foot and from inside to outside every section of the human apparatus.

Meanwhile he had been working on the monument, redesigning it to conform to the practical needs of casting. Now it had reached an even grander scale—a colossus that would require two hundred thousand pounds of bronze! He recorded in his notes the very day that this work was started, “On the twenty-third day of April 1490 I commenced this book and recommenced the horse.” The “horse,” of course, was the monument and “this book” referred to still another subject which had grown out of his studies of anatomy and perspective.

The title of the proposed book was to be _Light and Shade_. It would include the subject of optics or the mechanism of the eye, the problems of reflection and refraction and it would lead him eventually to a re-examination of his studies of the sun and moon.

In Leonardo’s day, and even for a long while afterwards, the popular belief of vision was one that had originally been put forth by the Platonic school and expanded by Euclid and Ptolemy. This belief was that the eye sent forth rays that brought back the image to the soul. Leonardo, in his younger days, had believed in the same theory. Not content with what had been written on the subject, however, he began to experiment for himself.

These experiments led him to an examination of the eye itself. He noted the various parts of the eye—the optic foramen or opening, the pigment layer, and the iris. These were already known by the Arabs. Leonardo discovered, however, the crystalline area of the eye. He explained binocular vision, or three-dimensional images, by correctly noting the positions of the two eyes in the head. He described the variations in the diameter of the pupil according to the surrounding light. Further experiments with light brought him to the conclusion that light and images are received by the eye. He took a piece of paper, for example, and pierced it with a small hole. With this he looked at the source of light. He noted the cone shape of the rays funneling into the tiny hole and then when the paper was held next to a white wall he noted that the rays spread out again. He established that light travels in straight lines. He constructed the first “camera obscura”—a box with a small hole in it. Inside the box an object was placed near the hole and behind that a lighted candle. When the box was closed the image of the object was cast on the wall. Leonardo was already acquainted with lenses, and he placed a magnifying lens over the hole to create an enlarged image.

He also demonstrated various laws relative to optical illusion, such as irradiation—when a metal rod is made red-hot at one end, that end seems thicker than the other. A brightly lit object seems larger than one exactly like it that is dimly lit; a dark object placed against a light background seems smaller than it is; a light object seems larger than its real size when placed against a dark background; and the illusion of a light swung in a circle appears as a complete circle of light.

Many years before Newton, Leonardo described the experiment of breaking up a ray of white light into the solar spectrum. Also he compared two sources of light and measured their intensity by the depth of their shadows accompanied by a drawing that was the forerunner of Rumford’s photometer three centuries later! He stated the law of reflection—that is, that the angle of reflection is always equal to the angle of incidence.

About this time Leonardo left the studio of Ambrogio de Predis and moved into the Sforza Castle. Ludovico had put at his disposal a studio in the Corte Vecchia and the use of a room in one of the towers—which Leonardo always kept locked. To his growing list of work, Leonardo now had to add the preparations for the delayed wedding reception of Ludovico’s nephew, Gian Galeazzo Sforza.

On a cold winter evening of January 1490 the guests assembled again. Silks, satins and gold brocade, diamonds, rubies and pearls glittered in the brilliant lights. Princes of the Church mingled with ambassadors of foreign lands. Music and perfume filled the air and as the party quieted down the entertainment began. There were dances in gay costumes. Poetry was recited that flattered the bride and groom. There were allegorical processions. The jokes and antics of the court jester made the audience laugh.

Then, at midnight, the curtain that hung from wall to wall at the end of the ballroom was raised. Applause and cries of delight greeted the spectacle. The rising curtain revealed a room in which there was a hemisphere surrounded by the signs of the zodiac and the planets. While the planets in their niches flickered with concealed lights and the signs of the zodiac glowed, lines were spoken in honor of the house of Sforza to the accompaniment of a choir. The ancient gods swept down from the heavens, and the Virtues and Graces moved across the scene with nymphs waving lanterns. The music drowned out the sound of the mechanism. This was the kind of mechanics that Ludovico could understand and appreciate.

The success of this entertainment so pleased Ludovico that Leonardo was encouraged to present another amusing idea. This one was an “alarm clock” and it utilized what we call today the mechanical relay principle. When a small power is suddenly switched over, the power is reinforced. The “alarm” clock worked by placing a shallow basin of water at one end of a tubed lever. At the other end was another empty basin. Water was led drop by drop into the second basin and as this slowly filled the increasing weight lowered the lever. The shallow basin of water at the first end was suddenly emptied and the immediate switch in weight flipped the lever up and this in turn pushed up the sleeper’s feet.

Leonardo decided to withdraw from the competition for the cathedral dome. Although the cathedral authorities were pleased with his design, they could not decide to whom the commission should be awarded. In the summer of 1490 Ludovico was called upon to settle the issue and he decided in favor of Antonio Amadeo from Milan. But the work that Leonardo had done so impressed Ludovico that he sent him to Pavia in company with an architect from Siena, Francesco di Giorgio Martini, to inspect the work on the cathedral of that city. Leonardo, who had his own workshop and apprentices now, took along one of them, Marco d’Oggionno, a young boy of twenty.

In Pavia one of the greatest libraries in all of Italy was in the ducal palace. Here Leonardo wandered among shelves of books and illuminated manuscripts bound in rich velvets and gold-embossed leather all bound to their places with silver chains. One book that he records in his notes was written in the thirteenth century by Witelo, a Polish scholar, who wrote extensively on perspective. Leonardo, by the necessity of his art, had solved many problems in perspective. He had invented a pair of proportional compasses, the forerunners of those used today for the transfer of a drawing from one scale to duplicate the same drawing in a larger scale. Leonardo had also designed in very careful detail a parabolic compass for drawing a parabola in one continuous movement. He now determined to write his own book on perspective and, as the subject was so close to his studies of the eye, he would entitle it _Introduction to Perspective, or the Function of the Eye_.

Leonardo submitted a number of plans for the completion of the cathedral to the authorities in Pavia and then returned to Milan. He worked through the rest of the summer on the equestrian statue and at the same time he continued to expand his notes on anatomy, light and shade, and perspective.

Late on a cold December night in 1490, Leonardo lit his lamp. This was a very special lamp that he had invented. It had already created a great deal of comment. It was so unusual, he had received an order from the court for another which he made with a richly carved pedestal. Candles, torches, and oil lamps, the only methods of artificial illumination in those days, were poor substitutes for light. They flickered, smoked, went out, and frequently caused damage with their hot drippings. As a side result of his experiments in light, Leonardo had put a glass cylinder in the middle of a larger glass globe. A wick in olive oil was placed in the cylinder and the outside globe was then filled with water. The result was a bright, steady light magnified by the water in the globe.

He sat down by the small fire and arranged his papers in front of him. Then, with a glance at his lamp, he picked up his goose-quill pen and wrote, “No substance can be comprehended without light and shade; light and shade are caused by light.”

7
_Success_

It was January of 1491, and a light snow had fallen in Milan, edging with white all the roofs, the massive spires of the cathedral and the red battlements of the Sforza castle. Soon Ludovico was to be married to Beatrice d’Este of the ducal house of Ferrara.

Once more the streets of Milan echoed to the carpenters’ hammers. Messengers rode to and from the castle and endless carts full of provisions pushed through the crowded city. Guests began to arrive from all the allied courts of Italy with their bodyguards and servants. The rooms of the castle, the palaces of the nobles, and even the inns were filling with the royal processions.

Leonardo was again summoned by the court to prepare the decorations, the costumes for the masquerades, and the arena for the jousting tournaments. An invitation had been sent to all the friendly courts to attend these contests-at-arms. So, accompanying each new party’s arrival was a band of armored knights, their breast-plates, helmets, and shields glistening in the winter sun.

Leonardo enjoyed designing mechanical toys and entertaining the guests with them. One of these was a mechanical drum. Ordinarily most of the entertainment began with normal drum rolls, but Leonardo’s rolls were made on a kind of wheelbarrow. On it was mounted an enormous drum. When the “wheelbarrow” was pushed, it put into motion a cogged wheel geared to the axle. This wheel in turn was geared to two rotary cylinders with pegs mounted around the top. The pegs moved against five drumsticks on either side of the drum and thumped out a rhythm according to the position of the pegs.

Ludovico’s marriage to Beatrice d’Este, a girl of little more than fifteen years, further isolated Leonardo from the court. Being almost a child, Beatrice loved parties and festivities, and she surrounded herself with people who catered to her frivolous whims. As a result so serious a man as Leonardo was forced into the background of the court life. He was called upon more and more to act as stage-designer while his more important work went unnoticed. Because these entertainments were easy for Leonardo to design, they did give him more time to work on his giant equestrian monument of Francesco Sforza. Working one day on the scaffolding surrounding the clay figure of his statue, Leonardo heard a knock at his studio door.

“Come in,” he shouted as he climbed down. “The door’s open.”

Three peasants cautiously entered the room and quickly took off their caps. One of them was holding a carefully wrapped bundle.

“Master Leonardo, we have brought you some shells we found on a ridge of Monferrato. Remember, you asked us to bring anything we found that was unusual?”

“Yes, Pietro. Thank you. Put them here on the table.”

Leonardo opened the bundle. He smiled when he saw the shells. He remembered how, as a young boy, he had found seashells like these high in the mountains. Leonardo questioned Pietro and his companions as to where they had been found and under what circumstances. He gave them some coins and, when they had gone, he looked among his growing collection of notes and drawings on the shelves. It took some time for him to find what he wanted, for the pages were in such confusion. Finally, he sat down at the table with several of the sheets and, putting the seashells in front of him, he began to make notes.

The shells were fossil shells but, thought Leonardo, their presence on the high mountains of Lombardy could hardly be attributed to the great flood as described in the Bible. In his notes, Leonardo cited the case of the cockle which, out of water, is like the snail. It makes a furrow in the sand and can travel in this furrow about three to four yards a day. By such means, he calculated, it could not possibly have reached Monferrato from the Adriatic in forty days (which was supposed to have been the duration of the flood)—a distance of 250 miles. Nor were these simply dead shells deposited by the waves—for the living creatures are recognized by being in pairs, and these in front of him had certainly been traveling in pairs. Consequently, they could have been left there only when they were alive and the mountains were covered by the primeval oceans. Moreover, Leonardo also described how living matter in prehistoric times fell into the mud and died, and how this mud, as the waters receded and years had passed, was changed into rock forming a mold about the fossil—literally making a cast of its original living appearance.

By such deductive reasoning and the testing of the evidence before him against the common beliefs, Leonardo struggled to free the minds of men from medieval superstitions and beliefs. Indeed, these medieval superstitions existed everywhere. Astrologers, or men who told fortunes by the position of the stars at a given moment; and necromancers, those who by tricks of magic claimed to be able to talk to departed spirits—these men profited from the ignorant. The Church, with its preaching of devils and hells, provided the background against which these fakers flourished.

Ludovico Sforza was himself a believer in such things. His own physician and astrologer was a man by the name of Ambrogio da Rosate, who had such influence over the court that he was given a post in the University of Pavia, and his fame was so great that he was called upon to predict the future of Pope Innocent VIII! Leonardo’s dislike of these men was intense. He scorned the supernatural and asked men to look about them at the real world and the real heavens. Observation and experiment—these were Leonardo’s key words. But he was a lonely figure in his thinking—like a man awake while the rest of the world slept.

At last the full-size model of the Sforza monument was nearing completion. Ludovico had ordered it ready for exhibition in the courtyard of the castle for yet another marriage festival that was soon to take place. This time it was the marriage of his niece Bianca Maria to Maximilian I of Germany. Leonardo and his assistants were busy with the finishing touches on the monument, and with building a wagon on which to carry it from the studio to the courtyard.

During these last months Leonardo had had to struggle with all kinds of heavy loads. Already he had improved on pulleys by inventing a new kind of tackle, and he also had utilized many kinds of levers. One of his simpler discoveries for raising heavy weights was a jack which, in appearance and principle, was the forerunner of our own automobile jack.

In 1493 when the clay model of the Sforza monument was completed, it was put on the cart and wheeled to its place of exhibition where a curtain was thrown around it. Again Milan was the host to a gathering of noble courts, and this time Ludovico outdid himself in the display of luxury. Tapestries hung from the buildings and rich carpets were laid down the steps of the cathedral. Everything that Milan had to show was on exhibition—even a crocodile.

But the most impressive sight of all was the unveiling of Leonardo’s colossal statue. It rose in majesty against the red walls of the castle. The name of Leonardo da Vinci was suddenly on everyone’s lips. As the word of his artistic achievement spread from city to city, messages of praise came pouring in. And, for a while the years of frustration and failure to gain recognition melted away. Leonardo at forty-one had at last achieved some success.

Now there was a breathing spell, and Leonardo returned to some of his own projects. For a long time he had continued his observations of his two favorite elements—air and water. To him they were related in their movements. The birds flying in the currents of air and the fish swimming in the flow of water seemed very similar to him. He had already designed various instruments to tell him about the direction of wind and its velocity, and he had also commenced to analyze the wing structure of birds and bats. To soar through the air like a bird was an ancient dream of man, yet for Leonardo it had become a passion. Ceaselessly, he sketched the flights of birds, the flutterings of butterflies and analyzed their flying patterns.

But to Leonardo, understanding the _dynamics_, or motion, of air was the most important thing. He built an _anemoscope_, an instrument like a weather-vane for telling the direction of the wind; and, he also constructed several types of _anemometers_ for measuring the velocity or force of the wind. One of these latter consisted of a thin rectangle of metal hanging straight down in front of an upward-curving wooden arc. This arc was marked off in units of measurement. When the wind blew, it pushed the thin rectangle up the arc; thus, by noting at which gradation it stopped, Leonardo could tell the velocity.

In addition, Leonardo at this time constructed a device which has been compared to the modern instrument used for testing the weight-carrying capacity of airplane wings. He fashioned a wing resembling a bird’s wing and attached it to a lever so that it would be possible to lower the wing by pushing rapidly down on the lever. This wing in turn was mounted on a plank that was in weight equal to that of a human being. He then calculated that two wings of this kind would have to be about twelve meters wide and twelve meters long to raise a man and his machine together. Another device resembling those found in airplanes today that Leonardo constructed was an inclination gauge. He made this by suspending a heavy ball on a cord within a glass bell. This ball was then supposed to guide the flyer by telling him whether he was flying level, diagonally, up, or down.

To Leonardo, water was also a phenomenon that from his youth never failed to excite his curiosity. The use of water power to run machines, to irrigate fields and to carry boats inland was a subject that he never ceased investigating. Out of his experiments at this time he constructed a device for raising water to high levels. It was based on the geometric spiral of Archimedes. He took a piece of gut, inflated it, and let it dry. Then, covering it with a coat of wax to make it waterproof, he wound it around a thin staff in a spiral. He put one end in a stream and attached it by gears to a cogged water wheel; this set the long screw to turning, and he was able to raise water from a low level to any height he desired. With a multiple system of these screws he could raise water in continuous circulation to the reservoirs on the highest towers.

In the year 1494, King Charles VIII of France crossed the Alps at the head of an army of twenty-five thousand men. Now Ludovico, by a series of diplomatic maneuvers, had allied himself with Charles and had, by secret negotiation, actually invited the invasion. By such an alliance he hoped to use Charles’ army to overcome the forces of the Pope which stood in the path of Ludovico’s ambition to become the most powerful ruler in Italy. Outwardly Charles was asserting his rights to the Kingdom of Naples, but inwardly he dreamt of leading a crusade against the infidels in the Holy Land. At the same time young Gian Galeazzo Sforza, Duke of Milan, was dying. Ludovico desired this title for himself; however, until Galeazzo was out of the way, he could not have it. There were ugly rumors that young Sforza had been poisoned. Moreover, in 1494, the Medicis—another powerful obstacle—were expelled from Florence, and a republic was established.

Soon young Gian Galeazzo died, leaving a son, Francesco. This son was the rightful heir to the Dukedom of Milan but Ludovico usurped the boy’s claim and declared himself Duke of Milan. Now Ludovico was in a position to await the impending battle between Charles and the Pope.

With such military and political ambitions in mind, Duke Ludovico now assigned Leonardo the task of reviewing Milan’s defenses. Again Leonardo submitted to Ludovico his plans for strengthening fortresses and designs for new ones. The great architect Bramante was also assigned the task of seeing to the city’s defenses, and for some time the two brilliant men worked together.

Then, in the spring of 1494, Leonardo was sent to Vigevano where Ludovico’s young wife was staying. This town was also the birthplace of Ludovico, and Leonardo was given the job of designing and building a small summer house and garden there for Beatrice. In addition, Leonardo built a kind of “air conditioner” for her bedroom. It consisted of a large waterwheel that cooled the air circulated into her room. Although this ancient device had long been known to the Greeks and Romans, Leonardo was the one who succeeded in perfecting it.

During this time Leonardo’s highly original mind was also at work on other devices. One of these was an _odometer_, an instrument for measuring the distance traversed by a vehicle. Dials, turned by a system of gears attached to the wheel of a wheelbarrow, measured the distance traveled as the barrow was pushed along the ground. In addition, Leonardo conceived a kind of odometer to be used at sea; this consisted essentially of a spinner that was towed by a ship which registered its speed. Leonardo even invented an automatic spit operated by metal vanes mounted in the chimney that revolved with the pressure of the hot air rising from the fire—and a pair of large floating shoes for walking on water!

In the meantime, Charles VIII of France had marched through Rome and entered Naples. The conquest was without opposition. Charles was then crowned King of Naples and all Italy was at his feet. Yet his triumph was a short one. Ludovico, having used the king to get rid of his enemies, now plotted against the king himself. He formed an alliance with the Pope, Venice, Spain, and the German emperor. Charles, faced with this league, hastily beat a retreat to France. Fighting his way to the border, he there signed a peace treaty. Thus Ludovico had swept Italy clean of all opposition and was now the most powerful prince in the land.

Yet Ludovico was quick to realize that his position could only be held by force and he set about strengthening himself and his allies. To provide for more cannons, a hundred and fifty thousand tons of bronze were sent to manufacturing works in Ferrara. This, however, included the very bronze Leonardo needed for the casting of his equestrian statue, and this is why the statue was never cast. Years of Leonardo’s work now seemed to vanish overnight. Ludovico also needed large sums of money to secure friends in high places and Leonardo’s own payments were suddenly dropped. Forced again to worry about paying for his daily bread and for his household and apprentices, he wrote letters to Ludovico complaining of his lack of funds and asking for money that was owed him for work done. He looked about for other commissions, but none were available. Moreover, because he was still court painter to Ludovico, he was ordered to paint the decorations of some rooms in the castle. But this was more than Leonardo could take—he walked off the job without finishing it.

Despite all of these misfortunes, Leonardo continued struggling with the problems of flight. He kept working out the proportions of wing span to the weight of the load. Indeed, he had already started designs for a flying machine. He had chosen a room which was the highest in one of the towers of the castle and which had access to a roof. Leonardo’s plans for a flying machine were a secret, and, with the exception of an assistant, no one knew about them. He made sure that he could not be seen by the workmen on the dome of the cathedral and proceeded to block off his room with beams which he planned to use as supports for his model.

He had thought at first that any attempted flight should take place over water in order to cushion a possible crash—but as his plans progressed he designed a parachute. It was a pyramid-shaped “tent of linen” twenty-four feet broad and twenty-four feet high, and it is believed to have been successfully tried out from a tower especially constructed for that purpose.

Since Leonardo was no longer working for Ludovico, he lived more simply than ever. He made regular lists of his expenses down to the last penny. His habits were frugal although he always kept himself neat. His meals were spare; he drank a little wine at meals and never ate meat. To his pupils and apprentices, he recommended regular habits such as not sleeping during midday, eating only when hungry and chewing well, exercising moderately, and sleeping well covered.

Yet, even though Leonardo lived cheaply, he was now greatly in need of money. Swallowing his pride, he wrote to Ludovico, placing himself at the duke’s service once again. His absence from court, he said, had been necessary so that he could earn a living. In this and other ways, Leonardo attempted to heal the break between them.

It turned out that Ludovico was glad to have Leonardo back. Perhaps mindful of the fame that the model of the equestrian monument had brought the house of Sforza, he now commissioned Leonardo to paint a picture. The Dominican monastery of Santa Maria delle Grazie was the nearest church to the Sforza castle and a favorite retreat of Ludovico. Here he used to walk in the quiet garden while the white-robed monks silently went about their chores. In gratitude for the peace he found there, Ludovico had had the refectory rebuilt and on the back wall, a crucifixion scene had been painted by Montorfano, a Lombard. But the front wall was given to Leonardo. On this Leonardo decided to paint a picture of the Last Supper—the painting that has since become one of the best known in the world.

8
_The French_

The noonday sun was baking the deserted streets of Milan as Leonardo hurried across the drawbridge of the castle. The guard dozing in the entrance arch started to his feet, but when he saw who it was he sat down again, muttering about a madman. Taking the shortest way, Leonardo arrived at the monastery gate and pulled on the bellcord. When the gate opened Leonardo brushed past the startled monk and made directly for the scaffolding in the refectory. He looked at his almost completed painting for a moment, took a brush and mixed a color swiftly on the large palette. Then he climbed the scaffolding and very quickly applied three or four strokes. With this he sighed and smiled. Then, just as abruptly, he put away his brushes and, without a backward glance, he left, making his way back to the castle in the hot sun.

For three years, Leonardo had been working this way on the “Last Supper.”

Sometimes he would work from dawn to dusk forgetting to eat; other times, he would stay away for days and then run back just to add a touch. Once he arrived and, with his arms folded across his chest, he stood in front of it for two hours just studying what he had done.

Now, in 1498, the painting was nearing completion and the only faces still left blank were those of Christ and Judas. Leonardo had drawn hundreds of sketches, taking his models wherever he found them—once he sketched a man just for his hands. Now that his name had become well known he always had an audience while he worked. His pupils, the monks, visiting nobility, church officials, and frequently Ludovico himself watched him as he painted the “Last Supper.”

But Leonardo, as usual, was involved in many different tasks. He was supervising the installation of a hydraulic pump over seventy feet high beside a stream which would use the power of the stream itself to pump water into the castle. Mindful, too, of the uncertainty of court patronage, he was designing commercial machinery, hoping thereby to secure an income outside the court. Among the most notable of these were an olive press, an automatic file-cutter, a hydraulic saw, and a needle sharpener. This latter was a forerunner of modern sharpeners with their mass-production methods. With it, Leonardo dreamt of sharpening four hundred needles at a time, or forty thousand an hour so that in twelve hours one person could sharpen four hundred and eighty thousand needles! The needles were arranged successively on a moving belt of leather and brought against a rotating grindstone. This grindstone was set in such a way that the needles were sharpened into curvilinear points rather than the usual triangular points.

In his travels to Vigevano and other parts of the countryside around Milan, Leonardo had studied flour mills. He had talked with the workmen, asked the prices of grain, and noted the time that it took to do the milling. Then he made calculations on ways to cut down the time, and, in fact, redesigned the entire mill. He mounted twelve cylindrical millstones in rows of four on one side of a canal and another twelve on the other side. In the canal were hydraulic wheels or paddlewheels. Each wheel was attached to a rod that ran underneath four millstones. Geared to the one rod were four grinding levers to the stones above. In this way it was possible to have twenty-four millstones operating at the same time.

But most fascinating to Leonardo now was the construction of his flying machine. His first models involved the principle of an air-screw mounted on a platform on which a man stood. But where would the necessary power come from to lift his machine from the ground? At first he thought of operating his air-screw by means of a steel spring coiled around a drum, but this he apparently abandoned. Later, however, Leonardo did design another model on this principle which has been called the forerunner of the modern helicopter. It was to be operated by four men standing on a platform. Each man would hold a bar which wound a spring-driven mechanism, much as in a modern clockworks. The air-screw was a broad blade spiraling about a vertical shaft—the ancestor of the modern propeller.

The model that Leonardo wanted to construct now, however, was of a different principle. Instead of an air-screw he substituted a pair of wings fashioned after those of the birds. There was still a platform on which the flyer stood and two springs were still the essential “motor” to raise and lower the wings. But as Leonardo worked on his apparatus he began to realize that it would be too much at the mercy of a sudden gust of wind or a violent updraft. It was necessary to return to his study of the air and its currents.

With all of this activity in mechanical devices Leonardo had reawakened his interest in mathematics. During this time he was introduced to a man at Ludovico’s court who became his friend and collaborator. He was a Franciscan monk named Fra Luca Pacioli who had been appointed a professor of mathematics by Ludovico. He, too, came from Florence, and in 1496, when he met Leonardo, he was forty-six years old and the author of _Summa di Arithmetica_, the first printed scientific work of his time. Pacioli was now at work on a book of geometry to be entitled _De Divina Proportione_ and he enlisted Leonardo’s aid in drawing the plates for his book. As Leonardo had already made a study of human proportions, the association with Pacioli was of benefit to them both. Among Leonardo’s best known drawings of human proportion is a beautifully rendered figure-study of a standing man with his arms at his sides and then outstretched, his legs together and then apart, inscribed within a square and a circle. It was made to illustrate a passage from Vitruvius on the proportions of a human figure and demonstrated, among other things, “the span of a man’s outstretched arms is equal to his height.”

Moreover, Leonardo found with Pacioli confirmation of many of his own observations and experiments and in turn Pacioli gave to Leonardo a confidence in his own methods. Pacioli also helped Leonardo with his arithmetic, a subject that Leonardo had neglected in his impatience to study geometry. The association also helped to free him further from the cobwebs of medieval beliefs. For Pacioli, the friendship with Leonardo was a revelation. Although Pacioli was a learned mathematician, Leonardo demonstrated to him that the application of his science encompassed _all_ sciences—even art—for Leonardo later wrote, “Let no one read me who is not a mathematician....”