The Polytechnic Engineer — Louis Le Chatelier

Louis Le Chatelier proved the value of the novel curriculum pioneered by the École Polytechnique and the École Centrale in Paris, which provided engineering students with a broad foundation in math and sciences and emphasized the application of new knowledge. “Techne,” the greek root shared by the words technique, technical, and technology, refers to the application of knowledge — know how.

Le Chatelier graduated from the École Polytechnique in 1836 at the top of his class. At the start of his career, Le Chatelier supervised mines throughout France, including the quarries of Paris, but he took the opportunity, beginning around 1840, to join the effort to create a national railroad network in France. Le Chatelier worked closely with Eugene Flachat to create and run a number of rail lines. Later, he joined the investment bank Credit Mobilier and helped to establish railways in Spain and Austria.

However, Le Chatelier was never far from the process of solving problems and innovation in the workshop. Le Chatelier was responsible for innovations in a diverse range of technologies: mine safety (safety lamp to prevent explosions), metallurgy (application of blast furnace to steel making and a process for refining aluminum), sewage treatment (use of alum sulfide as a flocculent).

Le Chatelier’s polytechnic training was tested by problems encountered implementing the entirely new technology of the railroad. Early versions of the steam locomotive jerked and rattled down the track. As larger, more powerful and faster machines were brought into service this became a problem that engineers had to solve. One of the first serious train accidents in France, a derailment and fire involving loss of life of passengers, was caused when the drive axel of the locomotive broke apart, possibly the result of metal fatigue from extreme dynamic loads.

Based on his training in theoretical mechanics, Le Chatelier had the insight that the forward and back oscillation of heavy pistons and drive rods and rotating drive wheels unbalanced by heavy crank arms were likely to destabilize the locomotive’s motion. In 1848, Le Chatelier suspended a full-sized locomotive 8 inches above the track and operated at speeds up to around 50 kph as it swung freely in response to the unbalanced forces generated by its operation.

Through these experiments, Le Chatelier demonstrated how adding counterweights to major rotating components can smooth the running of the locomotive and improved the its overall performance. Le Chatelier’s approach to balancing became an integral part of designing locomotives and other machines. However, assuring the stable motion of railroad trains moving at high speeds is a problem that has not yet been fully solved.

Louis Le Chatelier is one of the 72 engineers and scientists named on the Eiffel Tower. Le Chatelier’s son Henry is the chemist known for the discovery of Le Chatelier’s Principle.