"Galilei gives 17 propositions with regard to the fracture of rods, beams and hollow cylinders. ...[H]e supposed the fibres of a strained beam to be inextensible. There are two problems... discussed... which form the starting points of many later memoirs. They are the following:"
https://en.wikiquote.org/wiki/A_History_of_the_Theory_of_Elasticity_and_of_the_Strength_of_Materials