A Weight Poised Between the Centers of Two Worlds
How the elements meet where two earths touch, and where a weight falls between two centers
Leonardo poses two thought experiments about gravity toward more than one center. In the first, two terrestrial bodies with their elemental spheres touch, and a weight placed at the contact of their spheres of fire, pulled equally toward each center, descends obliquely and comes to rest on the point where the two earths touch. In the second, a uniform weight starting equidistant from the centers of two remote worlds falls along a path that keeps it always equally distant from both, halting midway without ever reaching either center; the margin diagrams label the centers and the weight.
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A weight at the meeting of two elemental spheres descends obliquely
Leonardo asks what figure the elements would take where two terrestrial bodies and their spheres touch. A spherical weight placed where the two spheres of fire meet, weighing equally toward each center, descends along an oblique line and rests upon the contact of the two earths, its motion oblique.
A weight equidistant from two world-centers halts midway (c, d e, a g b, f)
Given the centers of two worlds far apart and a uniform weight whose center of gravity is equally distant from both, Leonardo asks how it will fall. It moves for a long time along a path each part of which stays equally distant from both centers, finally stopping midway at the nearest such place, approaching neither center.
