Editing Nicolas Léonard Sadi Carnot (section)

=== Private studies and research ===
In Paris, Carnot befriended [[Nicolas Clément]] and [[Charles-Bernard Desormes]] and attended lectures on physics and chemistry at the [[Sorbonne University|Sorbonne]] and the [[Collège de France]]. He also attended the [[Conservatoire national des arts et métiers]], where he followed the lectures on chemistry by Clément and those on economics by [[Jean-Baptiste Say]].<ref>{{Harvnb|Fox|2012|p=425}}</ref>  Carnot became interested in understanding the limits to improving the performance of [[steam engine]]s, which led him to the investigations that became his ''Reflections on the Motive Power of Fire'', published at his own expense in June 1824.

Carnot was finally promoted to his former rank of captain in September of 1827, but the following April he quit the army, having completed only fifteen months of active service and without right to a pension.<ref>{{Harvnb|Almanza|Horsin Molinaro|Lo Bue|2024|p=5}}</ref>  In a directory of alumni of the École polytechnique published by Ambroise Fourcy in 1828, Carnot is listed as "maker of steam engines".  This and some other indications suggest that Carnot may have been involved in a practical scheme for the improvement of steam engines, but no patents or other concrete evidences of that work have emerged.<ref>{{Harvnb|Almanza|Horsin Molinaro|Lo Bue|2024|p=6}}</ref>