That Smoke, which is interposed between the Sun, and the Eye that sees it, must appear brighter and more Transparent, than the Smoke seen in any other part of the Painting: The same thing may be observed of Dust, Fog, and other like Bodies; which ought always to appear obscure, when you are placed between them and the Sun.

Smoke is more transparent, and of a Colour less deep towards the Extremes of its Masses, than in the Centre, and towards the Middle.

Smoke rises more obliquely, as the Wind which drives it is more strong, and violent.

Smoke, appears under as many different Colours, as there are different Causes to produce it.

Smoke, never projects any Shadows that are bold and defined; and its Extremes weaken by little and little; becoming insensible, as it removes further from its Origin: Those Objects, which are seen through it, appear so much the less sensible, as it is more Dense; and it is found so much the Whiter, as it is nearer its Principle, and the more Blueisn, as it is further removed.

Fire appears more obscure, as there is a greater quantity of Smoke, found between it, and the Eye.

Where the Smoke, is at the greatest Distance, Objects are the least dimm'd and intercepted by it.

Paint a Landskip, dim and confused, as if shrowded in a thick Fog; Smoke mounting in several Places, with Flames glaring in the lowest and thickest Volumes; and let the Roots of the Mountains appear less visible than the Tops; as we have already observed of Fogs.