This cyanotype was created by Anna Atkins in 1843 and it depicts Sargassum bacciferum, a type of algae. Anna Atkins was the first person to publish a book illustrated with photographs and she is regarded as one of the pioneers of the cyanotype process. This process does not require a camera—only sunlight, paper, and chemicals. Invented by John Herschel, a friend of Atkins, a cyanotype is created by hand-sensitizing a piece of paper with iron chemicals, placing it in direct sunlight with objects on top, and fixing the image with just water. There are no silver salts required in this process, and the blue color of the image is a result from the iron in the sensitizing chemicals. A cyanotype is technically a photogram—a negative image in which the shadows are inverted, leaving a white, sun-traced replication of the algae in the midst of a properly sun-exposed blue background. In fact, the cyanotype was the only photographic process developed in the nineteenth century to survive through the 20th century in widespread use, as in the blueprints used by engineers and architects. This technological advancement allowed Atkins to make photography books that enhanced the study of botanical life. Her work represents the beginning of photography as a method to enhance and spread scientific knowledge to a wider public.