This compilation Copyright (C) 2005 Mike Sebastian. No copyright claim is made to original U.S. Government works.
| U.S. Patent No. | Assignee | File Date | Issue Date | Inventor1 | Product | Title | Comments |
| 366945 | Chauncey W. Foster and himself (Felt) | July 6, 1886 | July 19, 1887 | Felt | Comptometer | Adding machine | - |
| 371496 | Chauncey W. Foster and himself (Felt) | March 12, 1887 | October 11, 1887 | Felt | Comptometer | Adding machine | Improvement to 366,945 |
| 396034 | Robert Tarrant and himself (Felt) | May 31, 1887 | January 8, 1889 | Felt | Comptometer | Adding machine | Improvement to 371,496 |
| 405024 | Felt & Tarrant Manufacturing Co. | January 19, 1888 | June 11, 1889 | Felt | (no printing Comptometers) | Adding machine | Improvement to 371,496; printing |
| 441232 | Felt & Tarrant Manufacturing Co. | March 8, 1889 | November 25, 1890 | Felt | (no printing Comptometers) | Type writing machine | Printing with hammers instead of direct pressure |
| 441233 | (none) | September 28, 1889 | November 25, 1890 | Felt | (no printing Comptometers) | Adding and recording machine | Printing mechanism refinements |
| 465255 | (none) | November 11, 1890 | December 15, 1891 | Felt | (no printing Comptometers) | Recording computing machine | Printing mechanism improvements: print knob, leading zero suppression |
| 568020 | (none) | September 10, 1894 | September 22, 1896 | Felt | Comptometer | Computing machine | Improved zeroing mechanism |
| 568021 | (none) | June 14, 1895 | September 22, 1896 | Felt | (no printing Comptometers) | Printing and calculating machine | Change to mechanism - number keys are set, then a lever is pressed to perform the addition |
| 590972 | (none) | April 28, 1897 | October 5, 1897 | Felt | (no printing Comptometers) | Duplicate printing mechanism for adding machines, type writers, &c. | Duplicate printing without carbon paper, using single mechanism and single ribbon |
| 628176 | (none) | May 31, 1898 | July 4, 1899 | Felt | (no printing Comptometers) | Tabulating machine | Printing mechanism can print in tabular form |
| 644287 | (none) | July 13, 1899 | February 27, 1900 | Felt | (no printing Comptometers) | Tabulating machine | Improvement to 628,176 - improved paper handling |
| 661121 | (none) | May 2, 1898 | November 6, 1900 | Felt | Comptometer | Calculating machine | Improvement to 568,021 - simplification of mechanism |
| 671109 | (none) | October 24, 1900 | April 2, 1901 | Felt | Comptometer | Calculating machine | Adaptions for British Money calculations |
| 693958 | (none) | August 17, 1899 | February 25, 1902 | Felt | (no printing Comptometers) | Duplicate printing mechanism for adding machines | Improvement to 590,972 – improved ribbon path for printing on two sheets of paper simultaneously |
| 694955 | (none) | November 19, 1900 | March 11, 1902 | Felt | (no printing Comptometers) | Tabulating machine | Printing - locks machine at end of sheet of paper |
| 711487 | Comptograph Co. | April 29, 1901 | October 21, 1902 | Felt | ? | Tabulating machine | Cross (row) tabulating |
| 733379 | (none) | November 3, 1902 | July 14, 1903 | Felt | Comptometer | Casing for key operated machines | Complete enclosure of mechanism to muffle noise - the classic Comptometer case style |
| 749177 | Comptograph Co. | September 12, 1902 | January 12, 1904 | Felt | Comptometer | Calculating machine | Mechanical improvements |
| 762520 | (none) | June 29, 1903 | June 14, 1904 | Felt | Comptometer | Calculating machine | Mechanical improvements to lighten the touch |
| 762521 | (none) | June 29, 1903 | June 14, 1904 | Felt | Comptometer | Registering mechanism for calculating machine | - |
| 767107 | (none) | August 3, 1903 | August 9, 1904 | Felt | Comptometer | Canceling mechanism for calculators | - |
| 780271 | Comptograph Co. | May 21, 1900 | January 17, 1905 | Felt | (no printing Comptometers) | Combined tabulating machine and writing machine | - |
| 780272 | Comptograph Co. | March 30, 1901 | January 17, 1905 | Felt | (no printing Comptometers) | Tabulating machine | Printing - locks machine when predetermined number of entries made |
| 780273 | Comptograph Co. | September 17, 1903 | January 17, 1905 | Felt | (no printing Comptometers) | Tabulating machine | Printing - different implementation to lock machine at end of column |
| 853543 | Comptograph Co. | December 27, 1904 | May 14, 1907 | Felt | Comptometer | Tabulating machine | Improvement to 749,177 |
| 889671 | Comptograph Co. | September 17, 1903 | June 2, 1908 | Felt | Comptometer | Total printing mechanism for listing machines | Pushing main operating lever back prints total |
| 960528 | (none) | September 16, 1908 | June 7, 1910 | Felt | Comptometer | Calculating machine | Improved canceling mechanism, idiot proofing |
| 982416 | (none) | April 4, 1910 | January 24, 1911 | Felt | Comptometer | Key for keyboard calculating machines | - |
| 982417 | (none) | August 22, 1910 | January 24, 1911 | Felt | Comptometer | Key for keyboard machines | Improvement to 982,416 |
| 992950 | (none) | December 18, 1909 | May 23, 1911 | Felt | Comptometer | Calculating machine | Lock keyboard if key not fully depressed |
| 996009 | (none) | March 4, 1910 | June 20, 1911 | Felt | Comptometer | Calculating machine | Mechanical improvements to lighten the touch |
| 1003723 | (none) | January 6, 1911 | September 19, 1911 | Felt | Comptometer | Key action for calculating machines | Change to pressure profile, heavyer initial pressure followed by lighter pressure |
| 1028344 | (none) | November 28, 1911 | June 4, 1912 | Felt | Comptometer | Calculating machine | Mechanical improvements |
| 1066096 | (none) | July 12, 1912 | July 1, 1913 | Felt | Comptometer | Calculating machine | Mechanical improvements |
| 1072933 | (none) | April 6, 1913 | September 9, 1913 | Felt | Comptometer | Calculating machine | Mechanical improvements |
| 1072934 | Felt & Tarrant Manufacturing Co. | April 5, 1914 | September 9, 1913 | Felt | Comptometer | Calculating machine | Improved canceling mechanism |
| 1074689 | Felt & Tarrant Manufacturing Co. | September 30, 1912 | October 7, 1913 | Bollensen | Comptometer | Adding machine | Adaptions for common fractions of high denominators |
| 1074704 | (none) | April 5, 1913 | October 7, 1913 | Felt | Comptometer | Calculating machine | Adaptions for fractions |
| 1074705 | (none) | April 5, 1913 | October 7, 1913 | Felt | Comptometer | Calculating machine | Improvement to canceling/zeroing mechanism |
| 1088219 | (none) | September 1, 1911 | February 24, 1914 | Felt | Comptometer | Calculating machine | Electric motor driven |
| 1110734 | Felt & Tarrant Manufacturing Co. | March 3, 1914 | September 15, 1914 | Ziehm | Comptometer | Calculating machine | Locking mechanism improvements |
| 1357747 | Felt & Tarrant Manufacturing Co. | May 1, 1918 | November 2, 1920 | Turck | Comptometer | Calculating machine | Improvement to canceling/zeroing mechanism |
| 1357748 | Felt & Tarrant Manufacturing Co. | December 1, 1919 | November 2, 1920 | Turck | Comptometer | Calculating machine | Improvement to 1,357,747 - canceling/zeroizing mechanism |
| 1371953 | Felt & Tarrant Manufacturing Co. | July 18, 1918 | March 15, 1921 | Turck | Comptometer | Calculating machine | Motorized |
| 1391220 | Felt & Tarrant Manufacturing Co. | April 24, 1920 | September 20, 1921 | Turck | Comptometer | Calculating machine | Second register |
| 1449639 | Felt & Tarrant Manufacturing Co. | May 19, 1921 | March 17, 1923 | Turck | Comptometer | Calculating machine | Locks canceling crank if erroneous partial key depression |
| 1818425 | Felt & Tarrant Manufacturing Co. | September 9, 1927 | August 11, 1931 | Niemann | Comptometer | Calculating machine | Keyboard locking mechanism to prevent erroneous entries from partial key depressions |
| 1886883 | (none) | April 23, 1921 | November 8, 1933 | Johnson | Comptometer | Calculating machine | Improved register control |
| 2570068 | Felt & Tarrant Manufacturing Co. | June 15, 1945 | October 2, 1951 | Niemann | Comptometer | Keyboard interlock for calculating machines | Improvement to keyboard locking mechanism when a key is partially depressed |
| 2585578 | Felt & Tarrant Manufacturing Co. | May 9, 1945 | February 12, 1952 | Niemann | Comptometer | Decimal indicator | Pivoting member can be moved to show or hide a painted spot through a hole in the case next to a number window to indicate a decimal point |
| 2835440 | Comptometer Corp | September 1, 1953 | May 20, 1958 | Koch | - | Flash reading indicating means for registers | Movable transparent colored filters move to distinguish groups of three digits in display window to improve reading accuracy |
Last updated November 5, 2006
