In 1843 the botanist Anna Atkins self-published *Photographs of British Algae: Cyanotype Impressions* — the first book illustrated with photographic images. Using Herschel's cyanotype process, she laid algae and ferns directly on sensitized paper and exposed them to the sun, fixing white silhouettes onto a deep Prussian-blue ground.

This system distills that monochrome blueprint vocabulary: a single saturated cyanotype-blue field, crisp white photogram figures, soft sun-exposed edges, and Victorian serif captions. The ground is always blue — never cream, never white.