Inclinometer

In his design of flying machines, Leonardo took into account not only the force of the pilot’s muscles, to be used for beating the wings, but also his dexterity, to be used for balancing and directing maneuvers.

Accordingly, he designed the inclinometer, an onboard instrument for aerial navigation, with which the pilot could control the position of the flying machine with respect to the ground, and thereby maintain the proper balance and inclination necessary during maneuvers for changing direction. The model is formed from a circular base topped by a glass bell, with a small pendulum hanging inside. A central position of the pendulum during flight would indicate to the pilot that the flying machine was at the proper horizontal position with respect to ground, whereas the bell served to protect the pendulum from interference due to gusts of wind.