distance is filled with air, that mass of air forms a dense body which intervenes and prevents the eye seeing the minute details of objects.
569.
Whenever a figure is placed at a considerable distance you lose first the distinctness of the smallest parts; while the larger parts are left to the last, losing all distinctness of detail and outline; and what remains is an oval or spherical figure with confused edges.
570.
OF PAINTING.
The density of a body of smoke looks white below the horizon while above the horizon it is dark, even if the smoke is in itself of a uniform colour, this uniformity will vary according to the variety in the ground on which it is seen.
IV.
OF PORTRAIT AND FIGURE PAINTING.
Of sketching figures and portraits (571-572).
571.
OF THE WAY TO LEARN TO COMPOSE FIGURES [IN GROUPS] IN HISTORICAL PICTURES.
When you have well learnt perspective and have by heart the parts and forms