I cannot forbear to mention among these precepts a new device for study which, although it may seem but trivial and almost ludicrous, is nevertheless extremely useful in arousing the mind to various inventions. And this is, when you look at a wall spotted with stains, or with a mixture of stones, if you have to devise some scene, you may discover a resemblance to various landscapes, beautified with mountains, rivers, rocks, trees, plains, wide valleys and hills in varied arrangement; or again you may see battles and figures in action; or strange faces and costumes, and an endless variety of objects, which you could reduce to complete and well drawn forms. And these appear on such walls confusedly, like the sound of bells in whose jangle you may find any name or word you choose to imagine. II. THE ARTIST'S STUDIO.--INSTRUMENTS AND HELPS FOR THE APPLICATION OF PERSPECTIVE.--ON JUDGING OF A PICTURE. On the size of the studio. 509. Small rooms or dwellings discipline the mind, large ones weaken it. On the construction of windows (510-512). 510. The larger the wall the less the light will be. 511. The different kinds of light afforded in cellars by various forms of windows. The least useful and the coldest is the window at _a_. The most useful, the lightest and warmest and most open to the sky is the window at _b_. The window at _c_ is of medium utility. [Footnote: From a reference to the notes on the right light for painting it becomes evident that the observations made on cellar-windows have a direct bearing on the construction of the studio-window. In the diagram _b_ as well as in that under No. 510 the window-opening is reduced to a minimum, but only, it would seem, in order to emphasize the advantage of walls constructed on the plan there shown.] 512. OF THE PAINTER'S WINDOW AND ITS ADVANTAGE. The painter who works from nature should have a window, which he can raise and lower. The reason is that sometimes you will want to finish a thing you are drawing, close to the light. Let _a b c d_ be the chest on which the work may be raised or lowered, so that the work moves up and down and not the painter. And every evening you can let down the work and shut it up above so that in the evening it may be in the fashion of a chest which, when shut up, may serve the purpose of a bench. [Footnote: See Pl. XXXI, No. 2. In this plate the lines have unfortunately lost their sharpness, for the accidental loss of the negative has necessitated a reproduction from a positive. But having formerly published this sketch by another process, in VON LUTZOW'S _Zeitschrift fur bildende Kunst_ (Vol. XVII, pg. 13) I have reproduced it here in the text. The sharpness of the outline in the original sketch is here preserved but it gives it from the reversed side.] On the best light for painting (513-520). 513.