Leonardo da Vinci, Pathfinder of Science

by Henry S. Gillette

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.