The Da Vinci Notebooks at sacred-texts.com
As to whether it is better that the water should all be raised in a single turn or in two?
The answer is that in one single turn the wheel could not support all the water that it can raise in two turns, because at the half turn of the wheel it would be raising 100 pounds and no more; and if it had to raise the whole, 200 pounds in one turn, it could not raise them unless the wheel were of double the diameter and if the diameter were doubled, the time of its revolution would be doubled; therefore it is better and a greater advantage in expense to make such a wheel of half the size (?) &c
The going down of the nave of the wheel must not be so low as to touch the surface of the water, because by touching the water its momentum will be lessened.
And if on the contrary the conduit for the water were ten times the size of the pipe for the water escaping from it, and if it had ten times less motion, what would be its office? This is answered by the 9th of this which says that the water would rise in the pipe whence it first flow, to a tenth part of its original height. 592
252:592 : 1076. The topographical interest of this passage arises from the circumstance that it is written on the reverse of the sheet on which we find the text relating to Romorantin, No. 1074.