As it turned out, Leonardo never finished this altarpiece. It is not known why. But the drawing for it can be seen today in the Uffizi Gallery in Florence just as Leonardo left it.
It is certain, however, that Leonardo was far from idle during this time. He drew the design for eliminating the friction of a turning axle by mounting the axle in roller-bearings. He experimented with, and solved the problem of, transmitting motion to revolving machine parts by friction—the possible forerunner of our modern friction clutch. Another device, found in modern automobiles—the differential—was also drawn by Leonardo. This idea provided for the difference in speed between the two drive wheels when rounding a curve.
Leonardo also drew the first known plans for a self-propelled vehicle—an “automobile.” It was designed to operate by a system of elastic springs wound by hand by the person on the vehicle; the “car” was then supposed to run the short distance allowed it by the unwinding of the springs.
In addition, Leonardo continued designing machines for both offensive and defensive military action. One of these was a breech-loading cannon, together with the first known projectiles that took into consideration better penetration through the air and greater stability in their trajectory. Indeed, these very much resembled present-day aerial bombs, with pointed noses and stabilizing fins.
As the months passed, however, Leonardo began to feel that his time and talents were being wasted in Florence. Although the monks and friends of the monastery were pleased with the work he was doing, other artists were being called to greater tasks in Rome. For example, Domenico di Tommaso del Ghirlandaio, Sandro Botticelli, and even Leonardo’s fellow student, Pietro Perugino, had left Florence to work in the chapel of Pope Sixtus IV in Rome—known to us as the Sistine Chapel. Now, too, it was becoming clear that Lorenzo and his court had no time for this solitary genius whose ideas stretched beyond his age.
So Leonardo looked about him. He was thirty years old and the walls of Florence seemed to bind his spirit. To what city could he go where his talents would be put to fruitful use? Rome seemed to hold out no hope, for no one had offered him a position there.
But Leonardo remembered that there had been a visitor to the Medicis from another city in recent months. This man was Ludovico Sforza, the ruling prince of Milan, the great city-state of the north. Ludovico, who was also called “Il Moro” (the Moor) because of his dark complexion, was seeking the friendship and alliance of the Medicis. He was fascinated with the art and culture of Florence and sought to gather to his own court of Milan as many artists, scientists, philosophers, and musicians as he could.
Perhaps, thought Leonardo, his future lay in Milan. So he began collecting his countless drawings, diagrams of machines and instruments of war, his notes, his plans for canals and irrigation—even a drawing for a monument that he knew Ludovico wanted to erect to his father—and made a package of it to send to Ludovico. Then he sat down to write a letter to that nobleman. In it he set forth in ten numbered paragraphs his qualifications as military and naval engineer, architect, and hydraulics expert. Almost as an afterthought to the tenth item, he wrote: “I can carry out sculpture in marble, bronze, or clay, and also I can do in painting whatever may be done, as well as any other, be he who he may.”
When he had finished the letter, Leonardo took out a strange instrument. It was a lyre of silver in the shape of a horse’s head. He had designed it himself, and now with an air of peace, he commenced to play. Its rich tone was sweet to hear and the music was his own composition.
Leonardo had also designed other instruments—lyres, lutes, viols, and a kind of zither. He had perfected the single-stringed monochord of Pythagoras, replacing the tablet of wood with thin strips of drum that gave the instrument a low or high note according to the tightness of the string. In addition, he introduced stops or small pistons in the holes of wooden reed instruments; and, he had even invented a set of mechanical chords by using a wheel of reeds which plucked a set of strings as it was turned. His skill as a musician, composer, and singer was well known among his friends and his bass voice had retained the pureness of his boyhood.