Part 8

As his notes began to take shape and he thought of printing them, it was natural for the inventive Leonardo to design his own printing press. It is one of the earliest such designs on record. Because the carrying bed which held the type and the paper was automatically adjusted to the handlebar, the press could be operated by one man. Besides his notes Leonardo also considered printing a work by Roger Bacon, the thirteenth century English scientist.

This project for printing his own books, however, was never realized by Leonardo. Lately, he had received a commission which took him back in memory to the days of Ludovico. The subject was Marshal Gian Giacomo Trivulzio, a soldier-of-fortune. Originally this man was a loyal commander of Galeazzo Sforza’s but when Ludovico came to power he had had Trivulzio banished from Milan. Embittered, Trivulzio had become a stubborn enemy of Ludovico from that time on, serving under any banner that marched against the house of Sforza. A stocky, square-faced man, his body was covered with the scars of many battles. He had been fighting with the French ever since the time Ludovico had betrayed Charles VIII. Trivulzio had seen the great monument that Leonardo had modeled and, although it was riddled by French arrows and damaged by wind and rain, the Marshal was impressed and wished for a similar memorial to himself.

Leonardo set to work immediately. His past experience with the Sforza monument was now to his advantage. This time there was no need for experimenting. He knew how much material he needed and the approximate cost of everything including the casting. He submitted an estimate of three thousand and forty—six ducats for the completed work, one hundred of which would go to Leonardo. The sum was acceptable to Trivulzio and Leonardo began his preliminary studies.

As he gathered the material for this new equestrian statue, Leonardo and the French Viceroy Charles d’Amboise became interested in the further canalization of the plains of Lombardy. The use of canals and locks had been in practice for roughly a hundred years and around Milan there were already some fifty miles of canals and about twenty-five locks. Leonardo started another survey of the area. In his imagination, he envisioned a vast hydraulic engineering project.

On September 12, 1508 Leonardo announced in his notes the beginning of a book on the nature of water. He had decided to separate this book from the one on hydraulics because it was necessary to separate theory and practice. His pages treating the science of hydraulics, or the practical applications of water power, had reached to “forty books of benefits.” By the spring of 1509 he had expanded his notes on the nature of water to include the greatest wave to the smallest raindrop.

Concerning the practical applications of water power, Leonardo put forth many designs for new locks. He introduced new methods of raising the gates by windlasses and chains which could easily be set in motion by one man. But most important is Leonardo’s discovery of the use of centrifugal force for draining marshes—the ancestor of the centrifugal pump. When you rapidly rotate a stick in a pail of water, the water spins in a spiral rising on the sides, and, if you rotate the stick fast enough it bares the bottom of the pail. When you remove the stick suddenly, the water continues to whirl as it slowly subsides.

This is basically the same principle Leonardo used to raise the water from a marsh to a level above the sea so that it could be drained away.

The centrifugal pump was also used with a hydraulic screw which converted water power to mechanical power. The force of a stream of water was injected into the base of a vertical cylinder. In the base of this cylinder was a six-bladed propeller mounted on a vertical shaft. The force of the water turned the screw and at the same time the water was forced to rise in the cylinder to an outlet above. The turning propeller revolved the vertical shaft. This shaft, emerging from the top of the cylinder, turned a cogged wheel. This wheel was joined to another cogged wheel mounted on a horizontal shaft, thus providing the mechanical power. Not only is this the forerunner of the turbine, but the use of the propeller, itself, for propulsion in water, was a new idea not to be thought of again until the eighteenth century. For certain types of hydraulic pumps he conceived of the cone-headed mitre valve still in use today.

Leonardo, besides studying the practical applications of water power, explored the very nature of water itself. In his proposed books on this subject he intended to examine why clouds and fog form, why rain falls and the raindrop itself—even how the raindrop is held together. He understood the nature of capillary attraction, which holds the raindrop together, and his notes show us that he was exploring the science of hydrostatics which relates to the pressure and equilibrium of liquids in general.

Now that Leonardo had a steady income and the relief from meeting painting commissions by fixed dates, he was free to explore his other favorite avenues of knowledge. It seemed that his ever-active mind could never stop roaming over the whole field of scientific knowledge. He continued with his early interests—the nature and movement of air, astronomy and geometry. He was also still concerned with movement and weight, for he set down in his notes, “The thing which moves will be so much the more difficult to stop as it is of greater weight.” This is a hint at a principle formulated by Isaac Newton almost two hundred years later in his First Law of Motion—the law concerning inertia. For example, the motion of an arrow shot into the air maintains itself in flight so long as the influence of the initial force is maintained in it.

On a note dated April 28, 1509 he wrote, “Having for a long time sought to square the angle of two curved sides ... I have solved the proposition at ten o’clock on the evening of Sunday.” As always, Leonardo was deeply involved in the study of mathematics. Too deep perhaps to recognize the new rumblings of war.

Louis XII, still pursuing his campaign in northern Italy, had again arrived in Milan amid the salutes of the French artillery. Following his personal banner of a gold porcupine on a white field, he had come back prepared to do battle with the Venetians whose power, as it diminished in the east, was extending westward into Italy. Alarmed at this Venetian expansion, the French King had allied himself with Pope Julius II and the powers of Europe to form the League of Cambrai to push back this threat. Charles d’Amboise, the French Viceroy, had already taken to the field and at the castle of Cassano, overlooking the Adda river near Milan, he awaited the arrival of his king.

By the end of May, Leonardo was in the saddle once more. Surrounded by the best knights of France and the nobles of Milan, he personally accompanied the French King as military engineer to the meeting with the Viceroy of Milan at Cassano.

During the next three months, through the battles and defeat of the Venetians at Aquadello where sixteen thousand dead were left on the field, and the siege of Caravaggio and the capture of Peschiera, Leonardo served as military consultant and map maker. More than ever his eye was attracted to the possibilities of utilizing the many rivers they crossed both for warfare and commerce. He envisioned making the Adda river navigable from Milan to Lake Como. During this time, he devised not only a revolving bridge but even one of two layers in a single span—the upper level for pedestrians and the lower one for vehicles.

By July, Leonardo had returned with the king and the French army to Milan. Here was planned a great celebration of the French victory over the Venetians. In front of the cathedral, to the delight of the hundreds of spectators, Leonardo devised a mechanical lion scaring a dragon out of an artificial lake into the beak of a cock which picked the dragon’s eyes out. After the festivities Leonardo returned to his everyday work. In time, he had a thriving workshop and as he became more and more preoccupied with his scientific explorations, his art commissions were turned over to his assistants. He did continue, however, to work on the plans for Marshal Trivulzio’s monument and in his preparatory work for this assignment he expanded his notes and drawings of comparative anatomy.

This renewed interest in anatomy led him to attend a lecture in the winter of 1509. The lecturer was Marcantonio della Torre, a young man in his late twenties and one of the best-known anatomists of the times. He had been a professor at the University of Padua, but this city had fallen into the hands of the Venetians. Marcantonio was forced to flee Padua and had settled at Pavia. The two men, when they met, recognized in each other a devotion to science and they began a professional collaboration that grew into a friendship. Leonardo now developed his anatomy studies to the point where he is today recognized as the foremost medical anatomist of the Renaissance.

Returning to his dissections, Leonardo now proceeded to explore the heart and system of veins in the human body. His drawings of the heart are nearly perfect. Indeed, he was probably the first to discover the endocardium membrane that sheathes the valves and sinews of the heart. Also, he pictured and described the moderator band, “the first cause of the motion of the heart.” His work on this organ led him to the doorstep of discovering the circulation of the blood—later to be carried out by William Harvey in the seventeenth century.

Further, Leonardo was the first to accurately draw a representation of the _foetus_, or unborn child, in the womb of its mother, writing in his notes that, “we conclude therefore, that a single soul governs the bodies and nourishes the two.” In addition, he drew a remarkable picture of the female figure and for the first time accurately placed her organic structure. In his notes, he also pointed the way to the laws governing metabolism when he wrote, “The body of anything whatsoever that receives nourishment continually dies and is continually renewed....” By pouring wax into a hole in the skull he made the first casts of the ventricles of the brain. Several hundred years were to pass before this method was rediscovered.

As Leonardo’s work progressed, his admiration for the complexity of the human body grew. Many times in the middle of explaining a section of anatomy he inserted a sentence or two of wonder or praise at the magnificent creation that is the human being. Indeed, these drawings and notes represent the sum of many, many dissections; moreover, Leonardo had to work under conditions that placed many obstacles in his path—the crude lights and instruments, the difficulties of obtaining corpses and, above all, the opposition of the superstitious and ignorant.

The following year Leonardo entered in his notes, “This winter of the year 1510 I look to finish all this anatomy.” And yet, however sincerely he might express such a wish, Leonardo was a person who was literally never “finished.” The scientific and artistic tasks he had chosen for himself were clearly beyond the limits of any one man. Besides, the pressures of the outside world were once more threatening the peace and quiet of his home and work.

Pope Julius II became increasingly fearful of the French victories over the Venetians. Secretly, he concluded a peace with Venice and, allying himself with his former enemy, he now turned against the French. When the conflict continued, Charles d’Amboise, the patron of Leonardo, was killed at the battle of Correggio. He was replaced by a new French Viceroy, Gaston de Foix. Although the Pope now hired Swiss mercenaries, this invasion from the North was defeated by the young Gaston. Not to be outdone, the Pope then brought in Spanish troops.

In the ensuing bloody battle at Ravenna, the French completely defeated the armies of the Pope and Spain, despite their use of battle-cars armed with razor-sharp sickles on their wheels—strangely like the early inventions that Leonardo designed for Lorenzo de’ Medici! Although the French were victorious, they lost their brilliant young leader, Gaston de Foix, and with him they lost their heart. As a result, they were soon disorganized. The Pope’s armies renewed their attacks, and the French began a long retreat.

Once again the plague infested Milan and Leonardo’s friend, Marcantonio della Torre, died of it. After some futile attempts at recovery, the French fled across the Alps and with them went Marshal Trivulzio. Milan was left temporarily under the martial rule of the Swiss, and Leonardo with only his few apprentices was left again without a patron.

Tired and prematurely old at sixty-one, Leonardo resignedly gathered his possessions together once more and with Francesco de’ Melzi and four of his loyal pupils, he turned his back on Milan for the last time. The date was September 29, 1513. Their destination was Rome.

12 _Rome_

“Name?”

“Leonardo da Vinci.”

“Where from and where are you staying?”

“We are coming from Milan by way of Florence. I have quarters being prepared for me at the Belvedere in the Vatican—by order of the Pope. Now, young man, let us pass.”

The guard at the Porta del Popolo changed his manner. He dropped his halberd and motioned to the other guards to let the riders through. He touched his helmet roughly and with a grin he said,

“I’m sorry, Sire—but you know how it is. All these people—there’s bound to be them that we don’t want here. Go ahead, your Excellency. Make way there!”

With these words he laid his spear against a jostling group of broad-hatted pilgrims blocking the entrance to the city of Rome.

Leonardo heeled his horse and with Francesco de’ Melzi at his side, followed by his servant and students, pushed past the crowd at the gate. To the left rose the Pincio hill with its stately pines where, in the days of Imperial Rome, Lucullus had walked in his gardens. But Leonardo had no time to look about. It was a damp December day, and rain threatened from the gray skies. He was tired, and as Francesco glanced at him he could see Leonardo pull his cape around him with a little shiver as the chill wind stirred the long, graying hair on his shoulders. They made their way through the crowded, noisy city. They crossed the Tiber and rode past Castel’ Sant’ Angelo, the papal fortress built on the tomb of Emperor Hadrian. After another inspection by the Swiss guards in beribboned uniforms of white, green and gold under their shining breastplates, they entered the walls of the Vatican. That evening after he had settled himself in the Belvedere apartments and dinner had been eaten, Leonardo, gazing into the embers of the fire, looked back over his new stroke of fortune.

The Medicis had returned to power. Pope Julius II had died, and Giovanni de’ Medici, son of Lorenzo, had become Pope Leo X at the age of thirty-seven. With his election to the head of the Christian world, the Republic of Florence became a city of the Medicis once more and Leonardo had received an appointment in Rome. Giuliano de’ Medici, Pope Leo’s favorite younger brother, in his new rise to power and wealth, became Leonardo’s patron. The two must have met sometime during the Medici’s exile. Leonardo was given the apartments in the Vatican and a salary of thirty-three ducats (approximately eighty-five dollars) a month and a workshop was fitted for him and his pupils. He was also assigned an exclusive German assistant named Georg.

The Pope’s court in the Vatican was like the Medici court in the Florence of Leonardo’s youth—multiplied by hundreds. Leo X saw himself as the center of the artistic world, and being a man of luxurious tastes with the wealth of the church behind him, the Vatican was soon filled with a mixture of the wise and foolish. Pompous classic-quoters, third-rate poets and clowns mixed with the world’s scholars and statesmen. The two greatest artists were Bramante, the architect and friend of Leonardo’s first years in Milan, and Bramante’s pupil Raphael, the painter.

Bramante was busy building the new church of St. Peter’s and, as the architect of this favorite project of the Popes, he was sole master of the Roman art world. Raphael, as his protege, was the recipient of the better painting commissions in Rome. The elderly Bramante and the thirty-year-old assistant were a famous pair in the Rome of 1513. Equally as famous, however, was Michelangelo; he was still living in Rome, but was without patronage after Julius II’s death. Leonardo’s old rival had scored his triumph with his extraordinary paintings in the Sistine Chapel.

Although the young Raphael, who owed so much to the example of Leonardo, now rode through the streets as a wealthy nobleman, Leonardo himself received no great commissions. While Pope Leo was indulgent of his brother’s whims he himself had no use for this tall, serious old man who roamed the shaded walks of the Vatican poking at the strange plants in the botanical garden or making drawings of the foreign animals in the private zoo. In reality, Leonardo’s patron, Giuliano de’ Medici was a weak man. He played at being a patron but, like his brother the Pope, he lacked the force and decision of his famous father Lorenzo. Nevertheless, he did give Leonardo one small commission for a picture. Immediately Leonardo, excited by the exotic plants in the Vatican gardens, commenced to experiment with them to find a resin to make a varnish with which to cover the future painting. Pope Leo made fun of him exclaiming, to the delight of his court, “This man will never get anything done, he thinks of the end before the beginning.”

This ridicule by the Pope made Leonardo a joke to many in the circles of the Vatican who were a little afraid of this strange man with the searching eyes. Leonardo also suffered the humiliations of a man who did not conform to the fashions of his day. His knowledge of Latin, for example, was weak and although he could read it with the help of a dictionary he could not speak it. And, among the people who surrounded the Pope, Latin was the only language allowed. Prizes of great sums of money and important positions were often granted on the strength of an improvised speech in Latin (with many quotations from the classical authors) or a flattering Latin verse. Faced with such setbacks and ridicule, Leonardo—not surprisingly—began to withdraw into himself.

And yet, Leonardo refused to remain idle—he had to work. The need for mirrors in the vast halls and rooms of the papal palace was great. Leonardo turned his mechanical skill to redesigning and improving methods of making them, and even inventing his own machines for the grinding of the glass. Also, for Giuliano, who dabbled in alchemy and magic, he made distorting mirrors and burning lenses. In addition, Leonardo invented a machine which could be run hydraulically for producing long strips of copper of equal width for use in soldering the mirrors.

But, with the making of these mirrors, Leonardo began to run into trouble with his German assistant, Georg. The boy was a loafer; he spoke little Italian and took every opportunity to spend his days with his countrymen in the Swiss guard. Leonardo tried to alter the situation by suggesting that the boy have his meals with him at his worktable, thus giving Georg a better chance to learn the language. This however did not appeal to him. Then, because Leonardo’s inventions were so extraordinary, he began to give away the secrets of their mechanisms to Johannes the mirror-maker, another German, who had been replaced by Leonardo in the favors of Giuliano. This naturally made Johannes jealous of Leonardo. Georg gossiped, too, and told stories about the old, eccentric man who lived like a miser in the midst of all the luxury and who drew crazy circles on pages of paper.

These “crazy circles” were geometric exercises that had fascinated Leonardo from the time he had wandered across Italy with Fra Luca Pacioli. Pacioli’s book _De Divina Proportione_, containing sixty illustrations from designs of Leonardo, had been published in Venice in 1509. Leonardo intended to entitle these geometric exercises _De Ludo Geometrico_. In geometry a lune is a crescent-shaped figure bounded by two intersecting arcs of circles on a plane or a sphere. Leonardo drew pages of these lunes and then proceeded to transform their curvilinear figures into squares of equal area. He also reviewed Archimedes’ method of squaring a circle and developed it into a variety of ways for cubing spheres and cylinders.

He returned as well to formulating theories of friction. He wrote in his notes, “the tallest wheel is the easiest to pull”—for example, a big wheel turning at the same speed as a smaller one has less friction to overcome because it makes less revolutions. His experiments in friction predated men like Amontons and Coulomb by two and three centuries. He established a formula for the building arch which he described as “a strength caused by two weaknesses”—if one half of an arch is removed, the other half collapses. They support and give strength to each other. In addition, Leonardo determined, before Galileo, the center of gravity of any pyramid and of a tetrahedral, or four-sided body.

As the days went by and he waited for commissions to come, Leonardo took to wandering about the streets of Rome. He stood in the half-buried Forum of the Caesars surrounded by grazing sheep and grunting pigs. Wooden shacks where crude cartwheels were made and where the marble from the ancient temples was cut and sold, were built against the sides of crumbling ruins. The old triumphal arches, now overgrown with creepers, were boarded into towers and cattle were penned between the shafts of columns that once supported the grandeur of temple roofs. Here and there a classical scholar would be sketching or writing from the worn, Latin inscriptions on a marble slab tilted crazily from the ground where it had fallen hundreds of years ago. Goats wandered on the Palatine hill, once the home of Emperors, and the great baths of the Emperor Diocletian were now a deer park and a hunting ground for royalty.

During the course of these wanderings, Leonardo became interested in the primitive methods of carpentry. Such things as screws, for example, were rare. Those that were used were either made of wood or, if of metal, by goldsmiths laboriously making each one by hand, soldering wire around a pin and another wire into the hole to hold the screw. Sometimes they were made by filing pieces of metal individually. All these methods were time-consuming and costly.

Leonardo had thought of this problem before, and now he concentrated on perfecting his ideas about it. Previously, he had thought of casting the metal in wooden molds and then turning the metal on thread-cutters. The designs he finally drew in careful detail, however, are essentially the methods used today. The new machines did with a few turns of a handle and adjustments of a few cogged wheels what it took one man many hours to perform. He also drew designs for a mechanical plane and a machine for drawing wire that worked by water power.

Leonardo now lived and worked in the Belvedere of the Vatican—more a man on exhibition than an active participant in the great artistic activities taking place around him. True, he received his thirty-three ducats a month, but Michelangelo had been paid three thousand for his work in the Sistine Chapel, while Raphael had earned twelve thousand for each room he painted in the Vatican.