Percussion and circular motion of water in a vessel
Ripples in a struck basin, a flame-cannon against gates, and wheel-and-pinion gearing
This verso is largely devoted to the percussion and motion of water: three basins are drawn with concentric rings, and the notes describe how a triangular disturbance at a vessel's centre spreads into an almost perfect circle, how waves reflect back and forth between centre and rim until they fade, and why water stirred in a circle sinks low in the middle. A separate note and a radiating diagram describe twin 'cortaldi' whose flame, joined at the angle of a pyramid, could break a gate by percussion once its towers had been cut down. At the lower margin two geared wheels are analysed, one with three rows of eight teeth driving an eight-rung lantern pinion (wheel n), with remarks on how teeth and rungs wear.
On this page
A triangular strike in a basin becomes a perfect ring
If the percussion made upon water at the centre of its vessel is of triangular figure, in long movement it becomes almost circular; after striking the banks it returns toward its centre and then to the banks again, until at the end the motion is of almost perfect roundness. Such motion occurs only in the part of the water that borders on the air.
Waves reflecting between centre and rim until they fade
Water enclosed in a vessel and struck at its centre makes circles that take that struck place as their common centre. But if the vessel is struck from outside, the circles begin at the water's contact with the vessel and run diminishing toward the centre; reaching it, they return outward growing to the wall, then inward again, so many times that they are finally lost.
Why stirred water sinks low in the middle
Leonardo sets himself the task of stating the cause why a finger moved in a circle around the centre of the bottom of a vessel full of water leaves that water, kept in circular motion, standing low in the middle.
Twin cortalds break a gate by the percussion of flame
A note describes the flame issuing from two 'cortaldi' (short pieces) joined toward one side of a pyramid at its angle. Such instruments, it says, would break any gate by the sole percussion of the flame, once the towers had been lowered and the defences removed and the device brought up to the gate.
A wheel of three rows of eight teeth driving a lantern pinion
A wheel having three rows of teeth, each of eight, requires a lantern pinion of eight rungs; teeth and rungs will wear equally when of the same material over equal time. The two wheels are placed so that the teeth do not meet the rungs of their pinions at the same spot, especially wheel n, though their powers differ.
Part of the sea rests on part of its bed
A brief statement of statics: if the whole sea rests upon the whole of its bed, then a part of the sea must rest upon the corresponding part of the bed.