To enable your self to manage the Perspective of Colours, and to make their Changes, Weakenings, and Degradations correspond to Nature; take the following Method. In some Open Champagne, chuse out several Objects placed at the distance of one or two hundred Fathoms from each other; be they Men, Trees, Houses, or the like. Now, if for instance, your first Object be a Tree, place a Glass over against it, and holding your Eyes steadily in the same Position, Design your Tree upon the Glass; tracing out the Contour from the Image before your Eye; having done this, retire backwards till such time as the Natural Tree appears nearly equal with that you have Design'd; Here you may colour the Figure, taking your Measures from the Object appearing at a Distance; and touching it with Care, and Attention, till at length it be brought to resemble the Natural Tree, both in Form and Colour; insomuch that by shutting one Eye, they may appear both painted alike, and both equally distant: Continue the same Course, with regard to the other Objects, at the Second and Third Distance; treasuring up such Pieces as you perform in this way, and consulting them on all Occasions, as Guides and Rules for your Conduct. By the Experiments I have made in this kind, it appears that the second Object, at the Distance of twenty Fathoms, beyond the first, diminishes four Fifths of its bigness.