Henri Édouard Tresca (12 October 1814 – 21 June 1885) was a French mechanical engineer, and a professor at the Conservatoire National des Arts et Métiers in Paris.

He is the father of the field of plasticity, or non-recoverable deformations, which he explored in an extensive series of experiments begun in 1864.

Tresca's criterion is one of two main failure criteria used today for ductile materials.

See comparison on the image left: Tresca was also among the designers of the prototype metre bar that served as the first standard of length for the metric system.

After the Convention of the Metre had been signed in 1875, the International Bureau of Weights and Measures (BIPM) in Sèvres, France made 28 prototype line standards of platinum-iridium.

Thus, to first order, the distance between the marks wouldn't change due to the slight sagging of the bar under its own weight between support points.