This was the second in a series of four articles by E. Buony. It described Paul de Vivie’s ‘quick link’ that allowed the rider to rapidly break the chain, move it to a different chainwheel/sprocket pair and speedily rejoin it.
Like oval chainwheels, ‘quick links’ have been repeatedly ‘invented’ and then forgotten throughout cycling history.
The article appears to describe a world in which there were only two manufacturers of bikes with variable gearing - Paul de Vivie in St-Étienne and a Monsieur Lavignasse in Dax.
(Source gallica.bnf.fr/ Bibliothèque nationale de France)