The height of the water in rivers will never rise one time as it did another, but will fall short or overshoot. The height of river water will never stand fixed in its being.

a - c - d b - f e; a - c - d b - f e. If two vessels ... If there be two vessels, each of uniform width in itself, and their heights are double one to the other, I say that if they are filled with water and then their equal orifices at their lowest point are opened at the same instant, the proportions of their sinking levels at every degree of time will go on increasing to infinity within a finite time. It is proved: let a b and c d be the proposed vessels, each of uniform width in itself, the width of one equal to the width of the other, and the height of one double the height of the other; that is, a b is twice as tall as vessel c d, and the orifices are made equal at the lowest point of the vessels, namely the orifices b and d. I say that if they are opened at the same time, the double proportion — the smallest proportion in its denomination that can be found among all the kinds of proportion — will grow to infinite magnitude through all the degrees of time up to the emptying of the smaller of these vessels. And this arises because, when the smaller and the greater vessel begin the flight of their waters, the flight is double, one to the other. And if we divide the height of the greater vessel into 12 equal grades and the smaller vessel into six of these grades, and then each of these grades is divided into another 12 minutes, here the proportions will never agree, because when the greater vessel has had its water diminished by one grade of height, the smaller vessel will have had its water diminished not by half a grade, but by so much less as its motion has become slower through the lessening of the weight of the water above its orifice.

144 minutes. 72 minutes. Remove 12 minutes from the greater water, 132 minutes remain.