The Comptometer

1. The Comptometer A mechanical calculating machine G4G12 presentation by Jaap Scherphuis www.jaapsch.net

2. Dorr Eugene Felt (1862-1930) Dorr E. Felt www.computerhope.com

3. Dorr Eugene Felt Prototype: 1885 Dorr E. Felt Applied Mechanical Arithmetic – Felt & Tarrant 1920 www.jaapsch.net

4. The first years “Woodie” Comptometer: 1888 Dorr E. Felt London Science Museum 2015, Jaap Scherphuis

5. The first years Dorr E. Felt

6. Felt & Tarrant Mfg. Co. Robert Tarrant Dorr Felt Dorr E. Felt www.history-computer.com

7. Felt & Tarrant Mfg. Co. 1899 Newspaper Advertisement Dorr E. Felt www.jaapsch.net “Woodie” Model: 1888-1903 About 6300 sold – now 100 remaining

8. The slow rise Model A Dorr E. Felt en.wikipedia.org/wiki/Comptometer Model A: 1903-1906 About 5700 sold

9. The slow rise • Several essential improvements: • Metal case • Number entered on upstroke • Simple clearing handle • ‘Duplex’: allow simultaneous keystrokes Dorr E. Felt Model A: 1903-1906

10. How it works

11. How it works: Addition 6789

12. How it works: Addition 6789

13. How it works: Addition 6789 5465

14. How it works: Addition 6789 5465 + -------- 12254

15. How it works: Subtraction 12254 103 - --------

16. How it works: Subtraction 12254 99999897 + -------- 100012151 12254 103 - --------

17. How it works: Subtraction 12254 103 - --------

18. How it works: Subtraction • 12254 • 103 • -------- • 12151

19. How it works: Subtraction

20. How it works: Multiplication

21. How it works: Multiplication 6789 1 x -------- 6789

22. How it works: Multiplication 6789 2 x -------- 13578

23. How it works: Multiplication 6789 3 x -------- 20367

24. How it works: Multiplication 6789 13 x -------- 88257

25. How it works: Multiplication 6789 23 x -------- 156147

26. How it works: Division 156147/12

27. How it works: Division 156147/12 1←12 - --- 3

28. How it works: Division 156147/12 1←12 - --- 361 1←12 - --- 24

29. How it works: Division 156147/12 1←12 - --- 361 2←24 - --- 12

30. How it works: Division 156147/12 1←12 - --- 361 3←36 - --- 0

31. How it works: Division 156147/12 1←12 - --- 361 3←36 - --- 014130 1←12 - --- 2

32. How it works: Division 156147/12 1←12 - --- 361 3←36 - --- 014130 1←12 - --- 271301 1←12 - --- 15

33. How it works: Division 156147/12 1←12 - --- 361 3←36 - --- 014130 1←12 - --- 271301 2←24 - --- 3

34. How it works: Division 156147/12 1←12 - --- 361 3←36 - --- 014130 1←12 - --- 271301 2←24 - ---13012 3

35. The slow rise 1903-1906 Model A: 5700 1906-1909 Model B: 8500 1909-1912 Model C: 12400 1913-1915 Model D&E: 7900 Dorr E. Felt www.jmgoldman.com www.jmgoldman.com www.jmgoldman.com Model A Model B Model C Model E

36. The breakthrough 1915-1920 Model F: 42400 Dorr E. Felt www.lindnilsson.dk

37. The breakthrough Dorr E. Felt Rapid Mechanical Calculation, ±1913, F&T 1917-10-18 The Morning Oregonian

38. The breakthrough Dorr E. Felt 1917-11-01 The Morning Oregonian

39. The breakthrough Dorr E. Felt Applied Mechanical Arithmetic, 1920 Felt & Tarrant

40. The golden years 1915-1920 Model F: 42400 1920-1926 Model H: 48600 1926-1938 Model J: 100900 Dorr E. Felt www.lindnilsson.dk www.lindnilsson.dk www.lindnilsson.dk Model F Model H Model J

41. The golden years Dorr E. Felt 1918-09-03 Indianapolis News

42. The golden years Dorr E. Felt Comptometer News Vol. VIII Issue 1, 1936www.jaapsch.net

43. The golden years Dorr E. Felt Comptometer News Vol. IV Issue 2www.jaapsch.net Comptometer News Vol. III Issue 3www.jaapsch.net

44. The golden years Dorr E. Felt

45. The decline Dorr E. Felt(1862-1930) www.johnwolff.id.au www.johnwolff.id.au Electric Model K: 1934-1950 Model M: 1939-1950 www.johnwolff.id.au Model 3D11: 1950-1961

46. Competitors & successors Dorr E. Felt(1862-1930) www.lindnilsson.dk www.johnwolff.id.au Bell Punch Sumlock 912: 1940s Bell Punch Comptometer: 1960s www.anita-calculators.info Anita Mk VII: 1961

47. See more at: www.jaapsch.net Jaap Scherphuis