In his travels through the countryside, Leonardo could not help but notice how primitive the mills were. Feeling how strongly the wind blew in from the sea, he designed a windmill with a roof that turned with the sails. For the mechanism inside he devised a band brake—a semicircle of wood into which the large cogwheel of the mill was forced. This mill resembles the “Dutch” mills of the Netherlands and was among the first of its type to be brought into existence.
In the fall Leonardo was at Imola. There he created another of his beautifully rendered maps. He drew this with the help of a magnetic compass of his own invention. It consisted of a board with an arc on it and a compass needle, and was probably the first magnetic needle on a horizontal axis. This time the map was of the city itself, the walls, the castle and the principal buildings all touched with color and the river winding through the fields. Drawn in the shape of a circle, it resembles a view through a telescope from directly above. In Imola, too, he met Niccolò Machiavelli, the famous historian and political scientist, who was an emissary from the Signoria, the Council which now governed Florence. These two men became friends and, later, collaborators in Leonardo’s scheme to make the Arno river navigable to the sea.
At this time Cesare Borgia, having achieved great success in his military campaigns and confident of his conquests, decided to return to Rome. With the disbanding of Borgia’s headquarters at Imola, Leonardo’s duties were finished. Together with his new friend Niccolò Machiavelli and two other Florentines, he left Imola and the service of Cesare Borgia to return to Florence.
In January of 1503, a mathematician named Giovanni Battista Danti attempted a flight in a machine that he had designed. This flight was part of the entertainment at a wedding reception in Perugia. Danti climbed into his apparatus on top of the tower of St. Mary of the Virgin. It was pushed off into the air, hovered a few seconds, then began slowly drifting toward the ground. But suddenly, one of its wings hit a building projection and it crashed. Danti was carried away with a broken leg.
The news of the event traveled quickly to Florence.
When Leonardo heard about it, he eagerly questioned all those who had either seen it or had heard it described first hand. Danti’s attempted flight excited Leonardo for now he realized that he was no longer alone in his search. With a sense of urgency he returned to the problems of flying. He felt now that the solution to flight might be in the swift gusts of air through the ravines and the spread wings of the eagle drifting high in the sky.
10
Shattered Hopes
Before Leonardo could return to the problem of flight, however, he was again faced with the necessity of supporting himself and his growing household. The small fees he received for taking on apprentices hardly covered the cost of housing and feeding them. Moreover, the equipment he had to buy for his scientific researches added further to his strained budget. So, when a servant from Francesco del Giocondo, a rich Florentine merchant, presented himself at the gate with the request that Leonardo accept a commission to paint Francesco’s wife, Leonardo was only too glad to accept. The name of Francesco’s wife was Madonna Lisa, or Mona Lisa for short. Leonardo painted her portrait on and off for the next three years. Thus, what started as a minor commission ended as the one painting—in addition to the “Last Supper”—that most people today associate with the name of Leonardo da Vinci.
Having secured this work, Leonardo turned back to his studies of birds in flight and the nature of air. The soaring wings of eagles and hawks and the way they rode the currents with hardly a dip of their spread wings guided Leonardo’s thinking from pure mechanics to machines that act more on the principle of the glider. He proposed to write a treatise on the nature of birds’ flight, and, with his usual thoroughness, he began to weigh, dissect, and reconstruct various types of birds and their wing structure. He realized that one of the main difficulties of gliding was maintaining balance, or, more accurately, maintaining the center of gravity. From previous observations Leonardo had noted that man is capable of making the same motions that a bird does. He had also measured the strength of a man’s legs and had calculated that man has twice the power in his leg muscles that he needs for standing. Consequently he began to redesign his machine making use of man’s arms and legs to operate or “flap” the wings instead of standing him on a platform.