English: The image shows a pneumatic locomotive used in the construction of the Gotthard Rail Tunnel and other tunnels of the Gotthardbahn and an attached carriage with an additional pressure container. Energy was stored in the form of compressed air in the two pressure containers of the locomotive and the trailer. The released expanding air was used to operate the motor of the locomotive. Steam driven compressors were readily available and for example in use to drive pneumatic drills. Most probably these compressors were also used to load the pressure containers outside the tunnel. (The first DC motors were just being developed and the AC motor was patented by Tesla only in 1888.) In contrast to steam engines the pneumatic engines did not require additional ventilation of the tunnel during its construction. Even using pneumatic technology the tunnels were poorly ventilated during construction resulting in poor work conditions.
The original is a photograph by Adolphe Braun published in a probably small edition book "Photographische Ansichten der Gotthardbahn" (58 photographs (28x23 cm2) mounted on each single page plus one two-page panorama), published around 1875 or shortly thereafter. The exact date of publication is not clear. The original in the book was photographed at an angle and the resulting image was clipped to show central detail and to reestablish a rectangular frame. The resulting image is somewhat distorted with respect to the original photograph by Adolphe Braun and very much reduced in resolution. The German caption of the photo in the book reads "Luftlokomotive" (literally: Air-Locomotive).