Léon Lalanne

[2] From 1839 he was working also with Jean-Claude-Républicain Arnoux, his future father-in-law, on the Ligne de Sceaux; he married in 1841.

[1] As a civil engineer, Lalanne became known for railway construction in Spain, Switzerland and Wallachia, where he was first engaged in 1852.

Russian operations against Ottoman possessions from July 1853, preceding the outbreak within months of the Crimean War, made his position untenable as French and British diplomats left.

[1] From 1853 Lalanne directed the construction of railway lines in France (Part route to Strasbourg, Ardennes, Boulogne and Calais, etc.

[8] With Charles Joseph Minard, another civil engineer of the Ponts et Chaussées, Lalanne is considered to have made important contributions to rigorous cartography.

[11][12] A paper of 1863 raised general considerations on transport routes and population distributions, direction later covered in work of Walter Christaller.

Half a century later Maurice d'Ocagne provided a general theory, founded in projective geometry, for the nonlinear scales related by nomography.

[19] Charles Darwin cited a paper by Lalanne from the same year 1840 on the geometry of honeycombs, in his Natural Selection manuscript.

In 1840 Lalanne wrote an encyclopedia article Technologie for Un million des faits that cited both Charles Babbage and Claude Lucien Bergery, in reducing the problems of manufacturing to "technology".

[22] The following year in a comparable article Essai philosophique sur la technologie for the Encyclopédie nouvelle, edited by Pierre Leroux and Jean Reynaud, and intended for a less popular readership, he attempted a definition of the neologism "cerdoristique industrielle"[23] of André-Marie Ampère.

[24][25] A strong critic of the principle of division of labour pushed to its logical conclusion, Lalanne picked up the reasoning of Pierre-Édouard Lémontey and took it further.