start it was difficult to find business partners for his invention. In 1922, he managed to establish a company Oko (Polish for: eye) to promote a simple amateur camera of his construction with the same name, which Prószyński intended to mass-produce for schools and the public. The economic crisis of the 1920s interrupted Kazimierz Prószyński's plans. He was busy with other inventions, such as simple home film projectors and reading machines for the blind, but did not manage to mass-produce any of them. During World War II and the German occupation of Poland, German Gestapo police discovered his workshop. They arrested Prószyński and his co-worker under the accusation of conspiracy. Released after 10 days, Prószyński did not manage to remove all suspicion. He was chased by Gestapo and had to move often to avoid arrest. On 25 August 1944, during the Warsaw Uprising, he was arrested. Kazimierz Prószyński died in the German concentration camp of Mauthausen in spring of 1945, as the prisoner number 129957, shortly before liberation. Kazimierz Prószyński is regarded along with Bolesław Matuszewski and Jan Szczepanik as one of the most important pioneers of Polish cinema and cinematography. See also List of Poles Timeline of Polish science and technology Further reading Władysław Jewsiewicki, Kazimierz Prószyński, Interpress, Warsaw 1974, (in Polish) Alfred Liebfeld "Polacy na szlakach techniki" WKŁ, Warszawa 1966 (in Polish) External links Kazimierz Prószyński on Who is Who of Victorian Cinema * 1875 births 1945 deaths Polish inventors People who died in Mauthausen concentration camp Cinema pioneers Polish civilians killed in World War II Film people from Warsaw Engineers from Warsaw Polish people who died in Nazi concentration camps