In the early days of photography, the control of sensitive material was an individual technique without standard. Until the dry plate era, when Mr. Ferdinard Hurter and Mr. Vero Charles Driffield, scientists and photographers, jointly researched on the reaction of sensitive material. In 1890, they announced their result, setting the first theory that we rely on till now, and is the foundation of Sensitometry.

With candle as light source, an equipment modified from a sewing-machine to hold the sensitive plate, a rotating sheet between the light source, with such simple set up, they produced the most important theory of Photographic Science. This shows that wisdom is far greater than expensive equipment.