An interesting lot of scientific and early aerial photographs by Gaston Tissandier (1843-1899) - Jacques Ducom (1864-1953). They did pioneering work in aerial photography from a hot air balloon.
During a balloon flight over Paris on 19 June 1885, the chemist and meteorologist Gaston Tissandier and the photographer Jacques Ducom carried a camera with a focal length of 56 centimetres. According to Tissandier, two or three of the flight photographs surpassed in sharpness anything that had been made up to that time in the field of aerial photography. However, he particularly appreciated the print of a photograph taken at an altitude of 605 metres on the Île Saint-Louis, ‘which is of a clarity that leaves absolutely nothing to be desired […]’. Both in Tissandier's account of the flight in the journal La Nature and in his book La photographie en ballon, published in 1886, a map was included for comparison with this aerial photograph, so that the public could convince itself of the topographical accuracy of the photograph taken.
Tissandier explained in his travelogue that with a magnifying glass you can discover unexpected details in this photo: for example, a pulley on the ship, people on the quay or chimneys on the roofs. Such an examination with so-called reading glasses would become the standard method for image assessment during the First World War. Because of the sharpness and clarity of the photos he presented, Tissandier suggested that his aerial photography technique should also be used by the military. After all, at an altitude of 600 meters "a balloon has nothing to fear from artillery fire and the photographer can work just as safely in the gondola as in his studio." However, he underestimated the future range of the cannons, the development of which was also not standing still - and fighter planes equipped with machine guns were probably still hardly conceivable in 1885. In the race between photography and weapons technology during the First World War, increasingly longer focal lengths were used to obtain detailed images even from great heights. [Michael Kempf, Fotomuseum Winterthur]

The first albumen print is mounted on it's original cardboard with title credits on the recto:
"Photographie en Ballon, par M.M. Gaston Tissandier et Jacques Ducom. Ascension du 19 Juin 1885. Altitude 605 mètres. La Seine, le port d'hotel de ville et le pont Louis-Philippe, a la pointe de l'île Saint-Louis."

mount ca. 24 x 31 cm
photo ca. 12,7 x 18 cm

The second albumen print is not mounted and shows several traces of use and age. Uneven trimmed. Probably a test print.

ca. 12,5 x 17,3 cm

The third version of this image is printed photomechanical. The screen for printing the halftone (autotype) is clearly visible. Titled in pencil under the image in an unknown hand.

paper ca. 15,8 x 25,7 cm
halftone image ca. 10,4 x 14,1 cm