Tensile strength of wire

"Experience of the force that a metal wire can produce in various lengths"

The device designed by Leonardo consists of a simple container filled with sand and a bucket. Through a small shutter the sand slowly falls into the bucket which is suspended on a metal wire. When the wire brakes and the bucket drops, the sand stops falling. Thus one can calculate the braking point, repeating the experiment with different materials sustaining the weights. Leonardo also senses that the length of the wire has an influence on its resistance.Codex Atlanticus, sheet 222
1486-1490