Which shadow is darkest; light, curvature and coloured lights
Four short chapters from the fifth part on the physics of shadow, light and the colours of illumination.
Four short chapters from the fifth part of the Treatise on the physics of shadow, light and colour. Leonardo states that a shadow is darkest nearest its origin, and deepest where enlarged because its two lights lie farther apart, and that light is greatest on a body of least curvature. Bodies lit by the open air without the sun cast shadows with imperceptible edges, while those lit by air together with the sun have over-sharp edges. A final precept observes that bodies lit by differently coloured lights rarely show shadow-colours truly corresponding to their lit surfaces. The page is unillustrated scribal text.
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Which shadow is darkest
That part of a shadow is darkest which is nearest to its origin. Where shadows are of greater quantity, the reflected and incident lights lie more remote from one another, so the shadow is less impeded and therefore deeper.
Light is greatest on the least-curved body
From one and the same cause, the light produced is of greater quantity upon a body of lesser curvature. Bodies lit by air without the sun cast shadows without perceptible edges, whereas those lit by air together with the sun cast shadows with edges of excessive sharpness.
Bodies lit by differently coloured lights
Bodies lit by different qualities of coloured light do not have illuminated surfaces whose colours match those of their shadowed parts, and rarely do opaque bodies show shadow-colours truly corresponding to their lit colours. This arises because the objects casting the shadow are neither of the body's natural colour nor of the illuminator's.