Olivetti Summa 15 Adding MachineOriginal vintage advertising poster for the Olivetti Summa 15 manual mechanical adding and printing machine designed by Natale Capellaro (1902 1977) and Marcello Nizzoli (1887 1969) in 1949. Great mid century illustration featuring a green Summa 15 machine above the title text and a stylised image of a wheelbarrow filled with colourful maths number blocks. The Italian company Olivetti (founded 1908) produced type writers, calculators and computers;