During the course of these wanderings, Leonardo became interested in the primitive methods of carpentry. Such things as screws, for example, were rare. Those that were used were either made of wood or, if of metal, by goldsmiths laboriously making each one by hand, soldering wire around a pin and another wire into the hole to hold the screw. Sometimes they were made by filing pieces of metal individually. All these methods were time-consuming and costly.

Leonardo had thought of this problem before, and now he concentrated on perfecting his ideas about it. Previously, he had thought of casting the metal in wooden molds and then turning the metal on thread-cutters. The designs he finally drew in careful detail, however, are essentially the methods used today. The new machines did with a few turns of a handle and adjustments of a few cogged wheels what it took one man many hours to perform. He also drew designs for a mechanical plane and a machine for drawing wire that worked by water power.

Leonardo now lived and worked in the Belvedere of the Vatican—more a man on exhibition than an active participant in the great artistic activities taking place around him. True, he received his thirty-three ducats a month, but Michelangelo had been paid three thousand for his work in the Sistine Chapel, while Raphael had earned twelve thousand for each room he painted in the Vatican.

Leonardo became interested in various methods of carpentry.

Thus Leonardo drifted farther and farther away from his painting. This, in itself, caused people to talk in the papal city. For he had earned fame as a painter, but his passion for science was regarded as strange and whimsical. Occasionally, he did receive a small commission from the workshop of Raphael, yet these were like the crumbs from a rich man’s table.

Even the toys Leonardo made at this period for the amusement of his patrons were looked upon as somewhat weird. For example, he would take small pieces of wax and mold them into strange little animals and then inflate them so that they floated in the air in front of a startled guest. Once he caught a curious lizard in the garden and spent hours putting scales all over the tiny body, attached to it a little beard and horns, then let it out from a box at a banquet. The guests jumped back with fear and the women became hysterical.

One of Leonardo’s jokes that has been passed down in accounts of his life at this period must have created quite a sensation. He showed the company the cleaned entrails of a sheep resting on the palm of his hand. After telling them to wait and watch he took the entrails in another room and with a bellows inflated them with warm air. As the entrails filled with air they expanded and extended. They crept into the room where the company waited. Slowly they grew and grew until they began to fill the room. The guests overturned their chairs in their hurry to get out of the way of this shapeless, translucent creature. Then Leonardo appeared, the air-filled entrails giving way before him, and said:

“Sires, this is but an example and symbol of virtue. As you can see, the smallest virtue is capable of the greatest growth.”

The guests laughed, but it was an uncomfortable laugh. Thus another story was added to the legend of Leonardo as an odd old man.