-photography

-calo for short

-Source

-with Niepce brothers busy working on Pyreolophore, instead it's William Henry Fox Talbot who comes out with his calotype which becomes dominant

-he gets patent on it in British Isles in 1841 hoping to get rich on it

-and it does work but weakens calotype industry in country till 1860s when patent expires

-and elsewhere it becomes way more major without patent, including innovation

-Source

-in 1862 Prussian photographer Julius Berkowski discovers that some uranium salts result in calotypic emulsions

-conclusion is it must be some invisible radiation