Quadrature of the triangle, proportion tables and perception

Quadrature of triangle a b d

The squaring of any triangle is done by making a square, one of whose sides is half the base of the triangle and whose height equals the triangle's height. For triangle a b d, taking half the base e d, one forms the square e d f e; and so the triangle is squared.

Tables of continuous and discontinuous proportion

At the foot, tables set out continuous and discontinuous proportionality. The proportion from the first to the third equals that from the first to the second doubled (double times double makes quadruple); from the first to the fourth it is tripled, composed of three doubles or three triples.

Ring on a cord suspended at unequal heights

A cord is threaded through a ring and suspended by its ends at two different heights. The ring settles the nearer to one support than the other, in proportion as that support is nearer to the ring's own height.

How distance deceives the sunlit eye

Our judgment does not place things done at various distances of time in their proper distances: things long past seem near, and near things seem ancient. So the eye, among distant things lit by the sun, makes them seem near, while many near things seem distant.

Angolo superiore sinistro:

Figura di corda sospesa con anello:

Figura geometrica colle lettere:

Figura geometrica colle lettere e i numeri:

Figura geometrica:

Figura geometrica colle lettere:

Figura geometrica:

In basso:

Upper left corner:

Figure of a suspended cord with a ring:

Geometric figure with letters:

Geometric figure with letters and numbers:

Geometric figure: