The Science of Composite Shadow; Church Studies
Light-and-shade geometry above; plans and domes of centrally-planned churches below
A dense study sheet on the science of shadow, turned in both directions as Leonardo wrote. He defines the 'composite shadow' cast by a single window light, showing that it loses darkness as it recedes from its inner edge and grades between the lit and dark faces of the wall; each surface, he argues, takes the colour of what it faces. Ray-and-shadow diagrams fill the upper half. The lower half is given over to studies of centrally-planned churches — octagonal and cruciform plans and ribbed domes in plan and elevation — with one small building plan marked 20 20.
On this page
Composite shadow from a particular light
The composite shadow f r b c cast by a single light loses darkness the farther it lies from its inner edge. Because every surface takes the colour of what faces it, the side r c seen by the dark wall a e partakes of that darkness, while the outer side seen by the light d a partakes of the light. Thus the extremes of the shadow are defined.
Shadow graded between a lit and a dark wall
In the space o p e h the shadow darkens toward the line p h and lightens toward o c. The line p h is darkest because it sees and is seen by the whole shadowy face of the wall b S, while the line o e is lightest because it sees the whole luminous window a b.
Dividing the treatment of light and shade
Leonardo opens by proposing to treat first 'the quality of divided lights' and then 'the mean contained by the extremes.' The plan divides into two parts: the extremes that contain the composite shadow, and the composite shadow within its extremes.
Plans and elevations of domed churches
The lower half of the sheet is filled with studies of centrally-planned churches — octagonal and cruciform plans with clustered chapels and ribbed domes shown in elevation. A small building plan carries the figures 20 20.