In July 1861 the board of directors for the southern region of the Paris-Lyon-Méditerranée Railroad commissioned Baldus to produce an album of views of the rail constructions and principal sites served by the line between Lyons, Marseilles, and Toulon. This line, especially the section linking Lyons and Avignon, followed trade routes established in antiquity alongside the Rhône, the most powerful river in France, whose strong current made navigation always difficult and perilous, and at times impossible. Perched on the very edge of the roadbed, Baldus photographed the track and the telegraph lines that ran parallel to it as they skirted along the east bank of the river at the Donzère Pass, the northern entrance to Provence. The ease with which the smooth rails recede into the distance and curve gently around the rugged cliff wall is an apt pictorial expression of the mastery of modern engineering over time and space. The photograph appears in the album "Chemins de fer de Paris à Lyon et à la Méditerranée."