What is the fine-grained topic of the following text: Claudet, Antoine Francois Jean "Mr. Claudet's Researches on the Theory of the principal Phaenomena of Photography in the Daguerreotype Process”, in The London, Edinburgh and Dublin philosophical magazine and journal of science.Series 3, volume 35, July-December 1849. Only return the topic.
Researches on the Theory of Photography in the Daguerreotype Process