What machine did Leonardo da Vinci design to test the strength of materials under tension?

Leonardo da Vinci designed a tensile testing machine to test the strength of materials under tension.

The apparatus applied a gradually increasing load to a sample, allowing Leonardo to observe how much force the material could withstand before stretching or breaking. Such experiments helped connect practical construction with measurable mechanical behavior.

Leonardo investigated the properties of wood, ropes, beams, and other structural materials because his work covered bridges, buildings, weapons, and machines. Understanding failure was especially important when a design had to carry heavy loads or resist sudden forces.

This invention is sometimes described as a weighing machine, but its purpose was different. A balance measures mass or compares weights; a tensile tester examines how a material responds when it is pulled. Leonardo’s approach anticipated later experimental engineering.