Self-regulating water measure with paired basins
A constant-flow apparatus that keeps the source pouring an even ounce
This crowded fragment gathers studies of a box-and-basin apparatus for delivering a steady measure of water. Notes lettered onto the little boxes instruct that a 'secret' reservoir be made, that the upper basin be exactly full when the one below reaches it, and that each pour out one ounce. A longer note explains the principle: the upper vessel must always retain a finger of water before fresh water arrives, and the lower must stay full, so that the source does not vary its outflow. A bearded profile head is drawn at the lower right, unrelated to the mechanisms.
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The paired basins and the secret reservoir
Instructions written onto a pair of little boxes direct that the 'secret' reservoir be made, and that the upper basin be exactly full at the moment the lower one reaches it. Further boxes are marked to pour out one ounce each, so the device meters water by fixed amounts.
Keeping the outflow constant
The upper vessel is to keep a finger of water always within itself before new water comes from above, and the lower vessel is to stay always full. In this way, Leonardo notes, the source does not vary its flow, more or less, and the delivery stays even.
Profile head
A bearded, aged male head in sharp profile is sketched at the lower right of the sheet. It stands apart from the mechanical studies and appears to be an incidental figure drawing.