Lock-gates, reflections in water, and the science of shadow
A gate must match its channel; moving-water reflections and derived versus primitive shadow
A pen-and-red-chalk page mixing hydraulics with the science of light. A note warns that no lock-gate should be narrower than its channel, or the water will form eddies and break the bank. Under the heading 'Perspective', Leonardo observes that reflections in moving water are always larger than the object, that the eye cannot judge where a high object must descend, and that a derived shadow only resembles its body when the light matches that body's shape and size.
On this page
A lock-gate must not be narrower than its channel
No lock-gate should be narrower than its general channel, because the water then makes eddies and breaks the bank. A small gate diagram accompanies the note at upper right.
Reflections in moving water exceed the object
Under the heading 'Perspective', the note holds that shadows or things mirrored in moving water—that is, water with small waves—are always larger than the object outside from which they arise.
The eye cannot judge where a high thing descends
A red-chalk study of eyes looking at a 'high thing' carries the note that the eye cannot judge where the high object must come down.
Derived versus primitive shadow
The derived shadow is never similar to the body from which it arises unless the light is of the same shape and size as the shadowed body; nor can it be similar in shape to the primitive shadow unless it strikes between equal angles.