On the Motion and Measurement of Water

LEONARDO DA VINCI 280

CAPITOLO XIV.

Experiment on many various cases of the sphere of water.

In a perfectly round drop of dew, one can consider various cases regarding the function of the sphere of water Leonardo uses "sphere of water" to describe both a literal drop and the theoretical shell of water that he believed surrounded the Earth in the medieval cosmological model., such as how it may contain within itself a solid body without the destruction of its surface (fig. 2. plate I.). First, let a cube of lead be taken, the size of a grain of millet original: "grano di panico." A common Renaissance unit of measurement for very small objects., and being joined to a very fine thread, let it be submerged within such a drop; you will see that such a drop does not lose its initial sphericity, etc.

CAPITOLO XV.

Of the position of water.

Every part of the surface of water desires to be situated at an equal distance from the center of its element. And that part of the surface which rises above the rest happens because of opposing motions original: "contrari moti." This refers to turbulence or waves where water is forced upward against its natural tendency to seek the lowest point. that overlap between it and the bottom, etc.

CAPITOLO XVI.

Of the rest of water.

Every part of water within other water that is without motion lies in equal rest with that which is situated at its same level. Here, experience shows us that if there were a lake of very great width, which lay within itself without motion from wind, or from inflow or outflow, and you were to remove a very small part of the height of that embankment original: "argine." Here referring to a dam or the natural containing wall of a lake. which is found from the surface of the water downwards, all that water which is found from the edge of said cut in the embankment upwards will pass through that cut; but it does not move, nor pull out of the lake with it, any part of the water found from the cut downwards.

In this case, nature—constrained by the reason of her law—wills that all parts of the surface of the water which are supported by embankments without any inflow or outflow, be equally supported by the Center of the World Leonardo refers to the center of gravity of the Earth. He believed water naturally forms a spherical shell around this center.. The demonstration is held here below. Let us say that the water of the said lake is supported by the embankments (fig. 8. plate I.) NOAF, and that NMRA is oil spread upon that water, and that the cut in the embankment is MN; I say that all the oil found from N upwards will pass through the break without moving any part of the water situated beneath it, etc.