Shooting an arrow farther, and a double water screw
Three combined motions double an arrow's range; a screw that recycles its water
The archer text in the left margin, with a small figure of a bowman, sets out both a technique and its mechanics: draw onto one foot with the other lifted as counterweight, brace the bow against a wooden rest from hand to breast, and at one instant leap forward, extend the bow arm and loose the string. Leonardo reasons that the leap adds one degree of impetus, the arm's extension two, and the string's release three, so an arrow driven by six degrees rather than three should fly twice as far. At the centre a double cochlea carries water from the flat screw S p into the pyramidal screw and back to its own centre. The sheet also bears further text below not included in this transcription.
On this page
Adding three velocities to double an arrow's flight
The forward leap, being swift, gives one degree of impetus to the arrow; the extending of the arm, swifter, gives two; the release of the string, swifter still, gives three. So if ordinary arrows are driven by three degrees and this one, done deftly all at once, by six, it must go twice as far.
Double screw carrying water back to its centre
When water is at the centre of the flat screw S p it enters the pyramidal screw n c; from c to p it forms a lever equidistant to a half-screw, from p it rises to the centre m e, and so from m to c, doing the like again. The device returns its water to its own centre to run on.
Bowman drawn in the left margin
A small pen figure of an archer bracing on one foot accompanies the marginal instructions, illustrating the stance and counterweight described in the text. Only the outward attitude of the shooting figure is shown.