that it shines through the central hole, then place any object or figure you please so close to the wall that it touches it and draw the outline of the shadow on the wall; then fill in the shade and add the lights; place the person who is to see it so that he looks through that same hole where at first the light was; and you will never be able to persuade yourself that the image is not detached from the wall.
[Footnote: uno piccolo spiracelo nel mezzo. M. RAVAISSON, in his edition of MS. A (Paris), p. 52, reads nel muro—evidently a mistake for nel mezzo which is quite plainly written; and he translates it "fait lui une petite ouverture dans le mur," adding in a note: "les mots 'dans le mur' paraissent etre de trop. Leonardo a du les ecrire par distraction" But 'nel mezzo' is clearly legible even on the photograph facsimile given by Ravaisson himself, and the objection he raises disappears at once. It is not always wise or safe to try to prove our author's absence of mind or inadvertence by apparent difficulties in the sense or connection of the text.]
526.
TO DRAW A FIGURE ON A WALL 12 BRACCIA HIGH WHICH SHALL LOOK 24 BRACCIA HIGH.
If you wish to draw a figure or any other object to look 24 braccia high you must do it in this way. First, on the surface m r draw half the man you wish to represent; then the other half; then put on the vault m n [the rest of] the figure spoken of above; first set out the vertical plane on the floor of a room of the same shape as the wall with the coved part on which you are to paint your