Photoapparatus

The glass industry uses oxides of rare-earth metals to finish glass; they are used to produce special types of colorless and stained glass (for example, for optical photoapparatus). Color television is a prospective new field for the use of europium and yttrium compounds.

Source: wiktionary

Our imports from the Soviet Union in 1970 will include inter alia 9.5 million tons of crude oil, nearly 1,500 million cu.m. of gas, iron ore /10.7 mil.tons/, hard coal /2.7 mil.tons/, grain /1.3 mil.tons/, artificial fertilizers and raw materials for their production /over 500 000 tons/, non-ferrous and rare metals incl.semi-finished products /nearly 200 000 tons/, cotton /60,000 tons/, sunflower seeds and vegetable oils /55,000 tons/, meat, butter, animal fats /36 000 tons/, chromium and manganese ore /nearly 250,000 tons/, ferro-alloys /over 100 000 tons/, but also 50,000 TV-sets, 65,000 transistorized radio-receivers, at least 11,000 cars, 2 mil. metres of cotton fabrics, 740,000 watches, photoapparatuses, agricultural equipment, grain harvesters, tractors, civil aviation equipment, analytical computers, nearly 1,000 pieces of various metal-working and machine tools, as well as scores of building and road-building machines.

Source: wiktionary

The spark chambers were photographed by pairs of photoapparatuses.

Source: wiktionary