Technical aspects of small emulsion chamber are discussed. Emulsion chamber is a detector which consists of nuclear emulsion plates and other light or heavy material plates. While a pure emulsion stack is likened to a micro bubble chamber, it could be compared to a complex counter detector assembly with super high spatial resolving power. It is possible to measure particle momenta by relative scattering method and trace back &ggr; ray cascades to vertices a few centimeters away. Charged secondary tracks could be examined for sudden changes in direction several centimeters from production vertices. ’’Invention’’ of the emulsion chamber enabled one to extend the power of pure emulsions to study very high energy interactions to tens of TeV, and it opend a new windnow for search of short‐lived particles.