In graphite, upper right: 40
In graphite, bottom right: AAt 148Y
Atkins’s images are all cyanotype photograms (cameraless photographs) created by pressing a plant sample and its handwritten label against a sheet of sensitized paper and then exposing it to sunlight. When the shape of the plant became visible on the paper, the green-tinted sheet was rinsed, washing away unexposed iron salts and turning the exposed area a rich blue. Atkins was an unusually well-connected scientist: her father chaired the February 1839 Royal Society meeting at which the British inventor and photographic pioneer Henry Fox Talbot made his "photogenic drawings" public, and she learned the cyanotype (blueprint) process directly from its inventor, John Herschel. Atkins began making albums of botanical studies in 1843, becoming the first to use photographs for taxonomic purposes.
Princeton University Art Museum: Handbook of the Collections, (Princeton, NJ: Princeton University Art Museum, 2013).