Thin-walled outlets and the three centres of a body
Wall thickness and outlet placement govern discharge; then a note on centres of gravity
Continuing the study of outlets, Leonardo argues that of two openings equal in width, shape and height, the one set in the thinner wall pours more water because the water has a shorter contact with the sides of the opening. A second figure shows that an outlet dropping lower on the outside than on the inside discharges more. The page then turns to a short theoretical note distinguishing three centres in a misshapen body: the centre of magnitude, of accidental gravity, and of natural gravity.
On this page
A thinner outlet wall lets more water pass (a, b)
Of outlets equal in width, shape and height, the one in the thinner wall pours more water in equal time because the water has a shorter contact with the sides of its opening. Thus a discharges more than b.
An outlet that drops lower outside discharges more
Of like outlets set on the inner side of the reservoir at equal height, the one that falls lower on the outside as it leaves its wall pours more water. Because a has its outlet lower outside than inside, a pours more than b.
The three centres of a misshapen body
Every misshapen body has three centres: of magnitude, of accidental gravity, and of natural gravity. If it embodied the centre of the world it would lack the centre of accidental gravity, and such a body can receive the centre of the world only at its centre of gravity, its centre of magnitude remaining apart.