Begin from the line *m f* with the eye below; then go up and do the
same with the line *n f*, then with the eye above and close to the 2
gauges on the ground look at *m n*; then as *c m* is to *m n* so
will *n m* be to *n s*.

If *a n* goes 3 times into *f b, m p* will do the same into *p g*.
Then go backwards so far as that *c d* goes twice into *a n* and *p
g* will be equal to *g h*. And *m p* will go into *h p* as often as
*d c* into *o p*.

[Footnote: The first three lines are unfortunately very obscure.]

Taken from
*The Notebooks of Leonardo da Vinci*
edited by Jean Paul Richter, 1880.

. . .

81,

Demomstration of perspective by means of a vertical glass plane.

83,

84,

The angle of sight varies with the distance.

86,

87,

Opposite pyramids in juxtaposition.

On simple and complex perspective.

The proper distance of objects from the eye.

91,

eye.

93,

94,

95,

96,

97,

The apparent size of objects defined by calculation.

99,

100,

101,

102,

103,

104,

105,

On natural perspective.

107,

108,