Leonardo, whose work—particularly his anatomical studies—had constantly been interrupted by the fortunes of war, had found another hospital in Rome where he could continue these studies. This time it was his intention to write a treatise on speech. He dissected and drew the anatomy of the larynx (the voice box), the vocal cords and the trachea (the air passage to the lungs), and all the muscles that control the movements of the tongue and the lips. If you pronounce each letter of the alphabet you will feel these muscles of the lips, especially with the letters “o,” “p,” and “f.” Carefully he noted how the air vibrations from the trachea form themselves into vowels and consonants, and he drew the membrane which, when air is pressed against it, makes the sound “aah.”
At this same time he was also busy finishing a treatise on painting which he had begun when he was working on the “Last Supper” for Ludovico Sforza. But it was for his knowledge of military engineering that he was sent to the city of Parma by the Pope on September 25, 1514. Here he stayed at the Bell Inn while examining the fortifications and other defenses of the city.
Leonardo’s patron, Giuliano de’ Medici, had been appointed governor of this particular area and, since Pope Leo X was fearful of two powerful countries, France and Spain, he was preparing the papal territory against possible invasion. Another fear of the Pope—and indeed of everybody in Rome—was malaria, the disease carried by the mosquitoes that bred in the Pontine marshes west and southwest of the city. At that time, however, no one knew the cause was mosquitoes; rather, they thought it was the bad air from the marshes.
As Leonardo had already been effective in draining the pestilential marshes of Piombino for Cesare Borgia and, later, those around Milan for Charles d’Amboise, he was assigned the same task for the Pontine marshes. He surveyed the entire area to the sea and made another extraordinary aerial type map. His recommendations included draining the entire area, enlarging and regulating the Martino river and cutting an extra outlet from the river Livoli to the sea. These plans were adopted some years later and parts of the marshes were drained successfully, yielding new land for the cultivation of crops.
By December of 1514 Leonardo had finished his treatise on speech and, possibly in an effort to attract the attention of the Pope, he submitted it to the Privy-Chamberlain, Battista dell’Aquila. As Pope Leo was surrounded by an army of secretaries and assistants who passed on everything submitted, this manuscript with its beautiful drawings was mislaid and lost and only a few notes and sketches remain.
The continual discouragement of his life in Rome was offset by a visit from his half-brother, Giuliano, around Christmas. Leonardo was held in esteem by his family despite the quarrel over his father’s and his uncle Francesco’s will, and his half-brothers were pleased to tell of their famous relative who lived in the Belvedere as guest of the Medicis. Yet they knew little of Leonardo’s scientific dreams and his lack of recognition in the papal city.
Often, Leonardo’s greatest comfort was to return to his notes. The challenge of geometry and the mysteries of the movement of air and water kept him from brooding about his lonely life. Francesco de’ Melzi, Leonardo’s young friend, had more and more taken over the practical responsibilities of his everyday life. Except for his workshop, where the troublesome Georg worked at the making of mirrors, and an occasional small commission for a painting, Leonardo was free to study.
In addition to his geometrical investigations, Leonardo now experimented with the science of statics (objects that are stationary), and dynamics (objects in motion). One of his most important discoveries in the science of mechanics came about during this period. Concerning the division of weight, he wrote, “There are three conditions of gravity of which the one is its simple natural gravity, the second is its accidental gravity, the third the friction produced by it. But the natural weight is in itself unchangeable, the accidental which is joined to it is of infinite force, and the friction varies according to the places wherein it occurs, namely rough or smooth places.” Thus he realized and formulated what composes the movement of an object. He found that movement is the result of separate forces acting upon the object from different directions, as for example, the initial push, the pull of gravity and the resistance of friction. And, before Galileo, Leonardo further experimented with objects dropped from a height. As the result of repeated experiments, he noted that the fall was being affected by the earth’s rotation. That is, the object dropped always fell in a slight eastward direction rather than vertically downward—a fact later proved conclusively by Isaac Newton and Robert Hooke in the next century.
He also became fascinated with spiral motion, such as is found in a spinning top or in a whirlpool of water. Because of his interest in hydrodynamics, or the movement of water, he began to sketch imaginary “Deluge compositions.” These were drawings showing the world—probably inspired by the Bible—in a chaos of wind and floods. They were based on his years of scientific research. Indeed, his drawings of actual whirlpools are still among the greatest of his scientific art. Today, with all the latest technical aids, such as dusting a whirlpool with powdered rosin and then photographing it, an accurate three-dimensional picture is impossible. Yet Leonardo, by sheer observation and analysis coupled with his genius for drawing, could reproduce the complicated shape of whirling water.
In the relatedness of his explorations of water, air and movement, and weight, he worked out the similarity between the laws of equilibrium controlling solids and liquids. The equation between the motive force and resistance that makes for equilibrium or balance in solids can be compared to the equation between the upward pressure of liquids and the downward pressure exerted on them.