Color plate depicts a man operating a magic lantern, specifically the Duboscq Megascope, to discern microscopic dispatches delivered in Paris by carrier pigeons. Homing pigeons were utilized for communication during the Siege of Paris in 1870 when Parisians were surrounded by German armies, preventing correspondence with the outer world. The pigeons carried a microfilmed dispatch which could be read upon magnification via a magic lantern projector, as pictured in this illustration.

This plate is from John Howard Appleton's (1844-1930) Chemistry, Developed by Facts and Principles Drawn Chiefly from the Non-Metals, published in 1884. Intended as an introduction to the study of chemistry, this volume contains illustrations throughout the text including color plates. Color plates have been digitized along with a selection of illustrations.