Anna Atkins’s Cyanotypes.

Anna Atkins (1799-1871) was a marine botanist and photographer who produced a collection of cyanotypes called Photographs of British Algae: cyanotype impressions. This image, titled Cystoseira granulata, is part of the New York Public Library collection called Ocean Flowers: Anna Atkins’s Cyanotypes of British Algae. Essentially, these are blueprints of sea vegetation, as the museum website explains:

Through her father, scientist John George Children (1777-1852) whose Royal Society circle included [Sir John] Herschel [the inventor of blueprinting]and William Henry Fox Talbot (1800-1877), Atkins was aware of the group’s experiments with photography. Talbot’s "photogenic drawing" technique involved placing a flat object against a light-sensitized sheet of paper (sometimes pressed beneath a sheet of glass to prevent movement and ensure a sharp image) and exposing it to sunlight until the area around the object began to darken. Herschel devised a chemical method to halt the darkening and "fix" Talbot’s silver-salt image – the basis for all photography until the digital era.

Hershel experimented with other light-sensitive metal compounds in addition to silver, and in 1842 discovered that colorless, water-soluble iron salts, when exposed to sunlight, form the compound known as Prussian Blue; unexposed areas remain unaffected and the salt rinses away in plain water, leaving a blue ‘negative’ image. Inexpensive and easy to use, the blueprinting process, or cyanotype, is familiar today as an artists’ medium as well as a popular children’s pastime.

Atkins used Talbot’s "photogenic drawing" method, arranging her specimens on sheets of glass for easier handling for repeat exposures, and adopted Herschel’s blueprinting process, to generate the multiple copies of specimen plates comprising Photographs of British Algae. She also used this same method to produce title pages and contents lists instead of having them conventionally typeset.