ABSTRACT
At the dawn of the twentieth century technical and polytechnical schools, scientific departments of universities, and sometimes industrial laboratories had important collections of scientific instruments. The wealthiest institutions kept in their store rooms up to several thousand different apparatus which usually came from the best British, German, and French workshops. Though most of the instruments were produced by specialized firms, many scientific laboratories had their own workshop where highly skilled technicians could repair and modify the apparatus or, in some cases, build special instruments and prototypes. Large universities and polytechnical schools had well equipped scientific cabinets and lecture rooms. Running water, illuminating gas and in some cases compressed air were generally available. Electricity was supplied both by the local network and by large storage batteries, which could be loaded by dynamos driven by small oil, gas, or steam engines. High voltage electricity was provided by induction electrostatic machines or by powerful induction (Ruhmkorff) coils. Because of their multiple uses (production of sparks, oscillating electrical discharges, electromagnetic waves and X-rays, etc.), the latter were among the most important apparatus of the time. The physicist Emilio Segré wrote: “The length of the available spark established the rank of importance of the laboratory like perhaps today the energy of particle accelerators. “ The lecture rooms, which were normally adjacent to the instrument store, could be darkened by black curtains, because of the current use of arc light lamps and projectors. They were used both for showing didactic glass slides and for performing optical experiments. In their lectures and for their experiments, professors and scientists were helped by one or more préparateurs, whose skill in manipulating instruments and preparing the apparatus was often unsurpassed.
