L''�lasticit� Des Solides Dans l''ombre de la Lumi�re

"The thesis covers a wide and very complicated area and is based on a large selection of sources including a few non-published sources. Kaouthar Messaoudi discusses the intresting relations between the actors of the story, their arguments about technical details as well as about methodology, and their personal antagonies and claims of priority. She sets the theory of elasticity in its proper physical context and makes it clear that the innovations of the theory were mainly made as a means to explain the behavior of light at transverse vibrations in the elastic ether. She also shows how the theory underwent a major change with the advent of thermodynamics and the associated energetic program in physics. About half of the thesis is devoted to a detailed summary and analysis of the 19th century mathematical methods in the theory of elasticity. This shows that Mrs Messaoudi has studied the original sources in detail. The summaries and analyses are often so detailes that the reader can follow the arguments. The thesis is the first comprehensive study of the history of the theory of elasticity in 19th century since Todhunter's book (1886)". Jesper Lützen