TIM calculating machine, c 1916.
© Science Museum / Science & Society Picture Library
TIM ('Time is Money') double counting mechanism machine no 13521 with metal cover, made by L Spitz & Co, Berlin. This stepped drum calculator mechanism machine was first introduced in about 1907 and was the first type of four-function calculator. It performs addition, multiplication, division and subtraction, has eight entry setting sliders, nine places in the revolution counter, with 15 places in the results register on each slide.