© Fonds historique / CNRS Images



Pendulum, photographed on February 17, 1933

Pendulum, photographed on February 17th, 1933. University of Rennes professor Paul-Marcel Le Rolland’s and Jean-Louis Foune’s pendulum was an instru¬ment designed to analyze frameworks so as to evaluate the constructions’ rigidity. The device was based on theprinciple of associated pendulums.The two inventors’ patent was publi¬shed in March 1927. The device consisted of “perfecting the processes and devices that measure the hard¬ness of a material.” The inventors explained that, for this purpose, they compared the movements of two pendulums. The first was equip¬ped with a knife or elastic blade, oscil¬lating at a fixed rate. The other had a convex surface that oscillated on top of a sample of the studied material. The comparison of these two move¬ments allowed the measurement of the sample’s relative hardness. Office national des recherches scientifiques et industrielles et des inventions.

Scientific topics

CNRS Images,

Our work is guided by the way scientists question the world around them and we translate their research into images to help people to understand the world better and to awaken their curiosity and wonderment.