Releasing a Flood of Water on an Army and City Walls
A river-fed plank barrier whose boards tip open at a gun-signal to flood a field or breach walls.
Leonardo describes a way to loose a rush of water upon an army and upon the bridges and walls of a city. A barrier is built across a river by driving piles as high as the bank, half a braccio apart, with boards set between them; once the water is impounded, raising the tie M makes the upper part of each board (a) swing forward and the lower part (b) back, so the boards turn edge-on and the water bursts free. He insists every sluice be opened at once at the crack of a gun, so the massed water strikes with a single impetuous blow, and on steep rivers one such gate be set every half mile. A label reads M - a - b - toward Lucca.
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Loosing a rush of water on troops, bridges and walls
A method to release a violent surge of water against an army and against the bridges and walls of a city, using a river as the source of the flood.
Piled boards that tip to free the water (a, b, M)
Drive piles as high as the river bank, half a braccio apart, and set boards between them; let the water fill behind. Raise the tie M and the upper part of the board a goes forward while the lower part b goes back, turning the boards edge-on so the water is free to flee.
All sluices sprung together at a gun-signal
Every cataract must open at the crack of a gun or other signal so all release at one time, letting the water strike the opposing target with a greater, more impetuous blow. On a very steep river make one every half mile, each sprung by a cord pulling all its catches, so the man who unlocks stays safe.