What does Ferdinand de Lesseps accomplish between the 1879 Congris International d'Ytudes du Canal Interocyanique in Paris and sailing for Panama in December that year?

When they arrive at Barbacoas, Ferdinand de Lesseps and his encounter the Chagres River, now flowing swiftly. At this point it is 600' wide. A massive, iron bridge has been wrenched apart, compelling train passengers to cross the river utilizing planks. They then catch another train on the opposite shore.