He was trained as an engineer, and he and his half brother Eugène Flachat built the Paris-Saint Germain and Paris-Versailles railway lines between 1833 and 1840.

[1] He was the son of Marguerite Charlotte Marthe Mony, who had divorced the Paris notary Pierre Jalabert in November 1799.

Their son Stéphane Adolphe Mony (1831–1909) also attended the Ecole des Mines but left without graduating.

[7] In 1832 Mony, as a member of the Collège de la Religion Saint-Simonienne, wrote a 4-page pamphlet on avoiding Cholera in Paris by supplying running water and a sewage system.

His popular book summarizing Charles Dupin's official report on the exposition argued that what before has been a display of an arsenal was now a contribution to universal peace and industrial development.

[10] In his 1835 Traité élémentaire de mécanique industrielle Flachat rejected the distinction that Charles Babbage had made between machines that transmit force and those that product it.

[11] Stéphane Flachat, his brother Eugène and his childhood friend Benoît Paul Émile Clapeyron participated in construction of the railway line from Paris to Saint Germain(fr).

[12] In 1837 Mony was made a knight of the Legion of Honour for his work on the Paris to Saint-Germain railway.

[2] On 17 December 1853 Boigues Rambourg & Cie was formed as a société en commandite par actions (publicly traded partnership) by the merger of seven firms with the Commentry Mine, the Montluçon Blast Furnace and the Fourchambault Iron Manufacturing Workshop.

The former owner families were removed from management, leaving Mony in charge with Eugène Glachant and Anatole Le Brun de Sessevalle as his assistants.

He was elected to the legislature for the 3rd constituency of Allier in a by-election of 11 July 1868 to replace Édouard Fould(fr), who had resigned.

[1] In the chamber he issued several reports on public works and was involved in discussions on the budget and on the strikes at Le Creusot.