'Nydia' Folding Plate Camera, by Newman & Guardia Ltd, London, c. 1900

After the invention of the dry plate process in 1878, portable darkrooms were no longer required to prepare photographic plates. Instead, light sensitive chemicals were held on the glass surface with gelatin - to be exposed when needed, rather thatn while wet. Such developments were superceded by the introduction of roll film at the end of 19th century - much lighter and less bulky than glass plates. Some professional cameras accommodated both plates and film to allow flexibility of use.