Leonardo da Vinci, Pathfinder of Science

by Henry S. Gillette

Leonardo soon found that he and Rustici had much in common. Rustici, too, collected the odds and ends of his journeys into the country. Flying about the house were a tame eagle and a raven, while, at dinner, a pet porcupine begged for food. Rustici, however, was a believer in alchemy and magic. To practice these arts the young man devoted one room to the strange mixtures which bubbled over flames as he attempted to change base metals into gold, or to call upon the spirits to predict the future.

Leonardo settled into the life of the house very quickly and even helped his friend on an important sculpture commission. This was a group composition of St. John between the Pharisee and the Levite for over the doors of the baptistry. He also started to gather together his scattered notes on all the subjects that he had written about, going through them making corrections and erasing the repetitions. Possibly Leonardo was considering the publication of all his material for he wrote, “Begun at Florence in the house of Piero di Braccio Martelli, on the 22nd day of March, 1508. This will be a collection without order, made up of many sheets which I have copied here, hoping afterwards to arrange them in order in their proper places according to the subjects of which they treat....” This “collection without order” of almost forty years extended into practically all branches of human knowledge, founded on years of observation and experiment. Indeed, it was the magnificent effort of one extraordinary mind to push back the curtains of ignorance in order to let the light of natural truth shine through to mankind.

In addition, Leonardo returned to his studies of anatomy and comparative anatomy. For this latter he made many beautiful drawings of the legs of animals as compared to those of man. With them, Leonardo tried to indicate man’s place in the natural order of the world. He pointed out that our physical bodies are basically the same as those of animals, and that the muscular and organic differences are those of function only. For example, bird and man have the same chest muscles, called the pectoralis. But the bird, in order to fly, has developed these into powerful instruments of motion. Man, on the other hand, has learned to stand and move in an upright position. He has developed the muscles of the back, called the erectores spinae, and those of the buttocks to hold him erect. Leonardo intended to enlarge upon his studies of comparative anatomy to include all living creatures, even the insects.

Meanwhile, the Viceroy of Milan was becoming impatient for Leonardo’s return. The judgment against his half-brothers had been settled in Leonardo’s favor, and he hastened back to Milan. By the summer of 1508 he was once more in the routine of the court’s activities. King Louis had granted Leonardo a regular allowance and it was the first time he had enjoyed such a long freedom from the concerns of earning a living. With these steady payments Leonardo now had the leisure and support to pursue his own multitude of interests.

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.