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 |
| 3574 | (none) | (none given) | May 6, 1844 | Hatfield | - | Machine for calculating interest | Lookup table imprinted on drum |
| 4632 | (none) | (none given) | July 14, 1846 | Van Der Veer | - | Teaching arithmetic | Table imprinted on drum with slotted sleeve for viewing results |
| 5746 | (none) | (none given) | September 5, 1848 | Baranowski | - | Reckoning machine | Lookup table imprinted on drum |
| 6403 | (none) | (none given) | May 1, 1849 | Haines | - | Calculating machine | Circular adding wheel |
| 6602 | (none) | (none given) | July 24, 1849 | Young | - | Calculating machine | Sliding bar adder |
| 7074 | (none) | (none given) | February 5, 1850 | Parmelee | - | Calculating machine | Sum indicated on a single racheted rod, key movement restricted to number of notches for value |
| 7331 | (none) | (none given) | April 30, 1850 | Van Der Veer | - | Board and log rule | Lookup table imprinted on drum placed inside common octangular board rule or measure used with lumbermen |
| 8329 | (none) | (none given) | September 2, 1851 | Young | - | Rules for calculating interest | Sliding bars with replaceable cards for computing tax or interest |
| 11726 | (none) | (none given) | September 26, 1854 | Hatfield | - | Machine for adding numbers | Circular adding wheel |
| 13800 | (none) | (none given) | November 13, 1855 | Saxton | - | Machine for adding numbers | Circular adding wheel with numbers in a spiral |
| 15565 | (none) | (none given) | August 19, 1856 | Hubbs | - | Machine for adding numbers | Circular adding wheel with numbers in a spiral |
| 18675 | (none) | (none given) | November 24, 1857 | Castle | - | Improved arithmometer for adding | - |
| 18692 | (none) | (none given) | November 24, 1857 | Hill | - | Improved arithmometer | - |
| 18711 | (none) | (none given) | November 24, 1857 | Smith | - | Machine for multiplying numbers | Lookup table on disk |
| 21236 | (none) | (none given) | August 17, 1858 | Nutz | - | Improvement in addometers | Chain adder with keys |
| 21243 | (none) | (none given) | August 24, 1858 | Burns | - | Addometer | Disk adding machine |
| 21621 | (none) | (none given) | September 28, 1858 | Newbrough | - | Machine for adding numbers | Circular adding wheel |
| 21921 | (none) | (none given) | October 26, 1858 | Young | - | Arithmetical proof rule | Sliding bar adder |
| 21941 | (none) | (none given) | November 2, 1858 | Castle | - | Improved arithmometer for addition | Keyed adder |
| 23637 | (none) | (none given) | April 12, 1859 | Winter | - | Improved adding-machine | Keyed counter |
| 24481 | (none) | (none given) | June 21, 1859 | Newbrough | - | Instrument for adding numbers | Circular adding wheel |
| 24990 | (none) | (none given) | August 9, 1859 | Campbell | - | Adding machine | Addometer with carry |
| 27418 | (none) | (none given) | March 13, 1860 | Ballou | - | Adding machine | Disk adding machine |
| 28006 | (none) | (none given) | April 24, 1860 | Nelson | - | Machine for adding numbers | Keyed counter |
| 30264 | (none) | (none given) | October 2, 1860 | Strode | - | Adding machine | Addometer with sliding guides to facilitate reading numbers from ledger |
| 31016 | (none) | (none given) | January 1, 1861 | Harris | - | Adding machine | Disk adding machine |
| 38374 | (none) | (none given) | May 5, 1863 | Crane | - | Improvement in tax calculators | Lookup tables |
| 39222 | (none) | (none given) | July 14, 1863 | Fowler | - | Improvement in adding machines | Sliding bar adder |
| 40105 | (none) | (none given) | September 29, 1863 | Jeffers | - | Improvement in adding machines | Disk adding machine with improved carry mechanism |
| 41898 | (none) | (none given) | March 15, 1864 | Alexander | - | Improvement in calculating machines | Disk adding machine with levers to move disks, and display drums for addition and subtraction results |
| 45482 | (none) | (none given) | December 20, 1864 | Dolbeer | - | Improvement in machines for counting | Circular adding wheel |
| 49168 | (none) | (none given) | August 1, 1865 | Strode | - | Improvement in adding machines | Circular adding wheel |
| 51972 | (none) | (none given) | January 9, 1866 | Rowland | - | Improvement in calculating machines | Circular adding wheel |
| 58347 | Samuel J. Kelso (inventor) & James Edgar | (none given) | September 25, 1866 | Kelso | - | Improvement in ciphering machines | Addometer with half-circle slots, and slide counter to assist with multiplication |
| 60475 | (none) | (none given) | December 18, 1866 | Chidester | - | Improvement in computing machines | Disk adding machine |
| 62677 | (none) | (none given) | March 5, 1867 | Parks | - | Improvement in adding machines | Two disk adder |
| 62882 | (none) | (none given) | March 12, 1867 | Pierson | - | Improvement in calculating machines | Interest calculator using lookup tables printed on polygonal cylinders |
| 65883 | (none) | (none given) | June 18, 1867 | Davies | - | Improvement in computing machines | Chain adder |
| 67786 | (none) | (none given) | August 13, 1867 | Mendenhall | - | Improvement in calculating machines | ? |
| 69647 | (none) | (none given) | October 8, 1867 | Farmer | - | Improvement in tallying instrument | Circular adding wheels |
| 70926 | (none) | (none given) | November 12, 1867 | White | - | Improvement in wages indicators | Wage calculations with lookup table on a cylinder |
| 73449 | (none) | (none given) | January 6, 1868 | Keiler | - | Improvement in calculating machines | Circular adding disk on threaded shaft; position on shaft indicates hundreds |
| 73732 | James A Loomis (inventor), Alonzo Johnson (inventor), & Charles Gifferd | (none given) | January 28, 1868 | Loomis | - | Improvement in calculating machines | Circular adding wheel |
| 73995 | (none) | (none given) | February 4, 1868 | Pierson | - | Improvement in calculating machines | Lookup table with sliding guide and aperture |
| 74170 | (none) | (none given) | February 4, 1868 | Strode | - | Calculating and registering machine | Circular adding wheel |
| 74641 | (none) | (none given) | February 14, 1868 | Wallworth | - | Improvement in computing apparatus | Multiplication lookup table on disk |
| 75322 | (none) | (none given) | March 10, 1868 | Webb | - | Improvement in calculating-apparatus | Circular wheel adder |
| 77736 | (none) | (none given) | May 12, 1868 | Hyatt | - | Improvement in tax calculators | Lookup table with sliding guide |
| 79209 | (none) | (none given) | June 23, 1868 | Corliss | - | Improvement in instruments for adding figures | Almost a pen calculator – stylus adder |
| 79272 | Charles Corless (co-inventor) | (none given) | June 23, 1868 | Spofford | - | Improvement in instruments for adding and registering numbers | Almost a pen calculator – stylus adder |
| 85229 | Sylvester Bissell and Andrew B. West | (none given) | December 22, 1868 | Johnson | - | Improvement in calculating-apparatus | Circular wheel adder |
| 90275 | (none) | (none given) | May 18, 1869 | Kummer | - | Improvement in computing tablet | Sliding bar adder – claims carry guides and slotted sides to bar |
| 94772 | (none) | (none given) | September 14, 1868 | Reffelt | - | Improvement in calculating machine | Circular adding wheel, with multiplication lookup table on reverse side |
| 95876 | (none) | (none given) | October 19, 1869 | Brown | - | Improvement in adding machines | Keyed circular adding wheel |
| 97974 | (none) | (none given) | December 14, 1869 | Sinclair | - | Improvement in price calculating devices | Lookup table on drum |
| 98720 | (none) | (none given) | January 11, 1870 | Swain | - | Improvement in adding machine | Disk adding machine |
| 99533 | (none) | (none given) | February 8, 1870 | Chapin | - | Adding machine | - |
| 100288 | (none) | (none given) | March 1, 1870 | Groesbeck | - | Improvement in adding machines | Addometer style adder with 1/3-circle slots |
| 106701 | Frank T. Leilich (inventor) & Michael Leilich | (none given) | August 23, 1870 | Leilich | - | Improvement in adding machines | Disk adding machine |
| 106881 | Eugene Humphrey | (none given) | August 30, 1870 | Spear | - | Improvement in adding machine | Sliding bar adder |
| 106999 | (none) | (none given) | September 6, 1870 | Chapin | - | Improvement in adding machines | Disk adding machine with scalloped disks for finger use |
| 109619 | (none) | (none given) | November 29, 1870 | House | - | Improvement in adding and subtracting registers | Circular adding wheel |
| 110520 | (none) | (none given) | December 27, 1870 | Warner | - | Improvement in adding machines | Circular adding wheel |
| 117169 | (none) | (none given) | July 18, 1871 | Hamilton | - | Improvement in adding machines | Adder |
| 121687 | (none) | (none given) | December 5, 1871 | Teasdale | - | Improvement in calculating machines | Disk adding machine with crank |
| 129335 | (none) | (none given) | July 16, 1872 | Grant | - | Improvement in calculating-machines | Device capable of multiplication or division by successive addition or subtraction |
| 129531 | (none) | (none given) | July 16, 1872 | Coldwell | - | Improvement in interest calculators | Lookup table on disk |
| 130244 | (none) | (none given) | August 6, 1872 | Robjohn | - | Improvement in calculating-machines | Key locking mechanism |
| 130404 | (none) | (none given) | August 13, 1872 | Barbour | - | Improvement in calculating-machines | - |
| 133188 | (none) | (none given) | November 19, 1872 | Barbour | - | Improvement in calculating-machines | Simplification to 130,404 |
| 137107 | (none) | (none given) | March 25, 1873 | Stephenson | - | Improvement in adding machines | Addometer with carry |
| 138245 | (none) | December 30, 1872 | April 29, 1873 | Grant | - | Improvement in calculating-machines | Improvement to 129,335 |
| 140146 | (none) | August 11, 1871 | June 24, 1873 | Linderoos | - | Improvement in adding machines | Circular adding wheel |
| 143184 | (none) | June 13, 1873 | September 23, 1873 | Pool | - | Improvement in adding machines | Adding machine with concentric rings |
| 144523 | (none) | August 21, 1873 | November 11, 1873 | Esersky | - | Improvement in calculating machines | Abacus like device |
| 146407 | (none) | June 7, 1873 | January 13, 1874 | Spalding | - | Improvement in adding machines | Adding wheel with key entry |
| 150973 | (none) | December 6, 1873 | May 19, 1874 | Pettibone | - | Improvement in tax calculators | Lookup table on disk |
| 152670 | (none) | April 25, 1874 | June 30, 1874 | Moore | - | Improvement in adding machines | Addometer mechanical improvements |
| 153522 | (none) | April 1, 1874 | July 28, 1874 | Baldwin | - | Improvement in adding machines | - |
| 153826 | (none) | April 21, 1874 | August 4, 1874 | Holman | - | Improvement in adding machines | Adding wheel |
| 155772 | Elmore W. Taylor (inventor) and Richard T. Taylor | May 21, 1874 | October 6, 1874 | Taylor | - | Improvement in adding machines | Circular adding wheel |
| 157690 | (none) | May 19, 1874 | December 15, 1874 | Lawrence | - | Improvement in adding machines | Adder where values to be added are entered by pulling on tapes/bands |
| 158853 | (none) | June 10, 1873 | January 19, 1875 | Martin | - | Improvement in mechanical calculators | Moving bar adder with coupled lookup table |
| 159244 | (none) | September 8, 1873 | February 2, 1875 | Baldwin | - | Improvement in calculating-machines | - |
| 165964 | Alfred C. Wellman (inventor) and B.W. Griffin | February 15, 1875 | July 27, 1875 | Wellman | - | Improvement in calculators | Chain driven arithmometer-type adding/display mechanism |
| 168080 | (none) | February 1, 1873 | September 28, 1875 | Barbour | - | Improvement in calculating machines | Four-function with printing |
| 170708 | (none) | November 30, 1874 | December 7, 1876 | Butt | - | Improvement in adding machines | Circular wheel adder |
| 172270 | (none) | August 6, 1875 | January 18, 1876 | Kilbourn | - | Improvement of calculators for manufacturers of picture frames | - |
| 207918 | (none) | July 5, 1878 | September 10, 1878 | Verea | - | Improvement in calculating-machines | - |
| 209416 | Konigss-Berger & Co. | July 13, 1878 | October 29, 1878 | Odhner | - | Improvement in calculating-machines | Four functions |
| 251823 | Bennett D. Mattingly, half-interest | March 31, 1881 | January 3, 1882 | Bouchet | - | Adding machine | Adding mechanism improvements |
| 293809 | (none) | October 10, 1883 | February 19, 1884 | Spalding | - | Adding machine | Sums indicated with dials |
| 308528 | L.W. Noyes | October 18, 1883 | November 25, 1884 | Stark | - | Adding machine | - |
| 312014 | (none) | July 4, 1883 | February 10, 1885 | Pottin | - | Recording and registering apparatus for tills | Cash register |
| 314561 | M.F. Madden, one-third assignment | April 4, 1884 | March 31, 1885 | Bouchet | - | Adding machine | Adding mechanism improvement utilizing curved rack-bars and toothed roller |
| 384373 | (none) | March 26, 1887 | June 12, 1888 | Ludlum | - | Adding and writing machine | Adding machine with mechanical typewriter-like print mechanism |
| 414959 | (none) | April 28, 1888 | November 12, 1889 | Webb | - | Adding machine | Circular wheel adder |
| 420667 | (none) | April 12, 1886 | February 4, 1890 | Selling | - | Calculating machine | Calculating mechanism |
| 538710 | (none) | December 23, 1892 | May 7, 1895 | Steiger | - | Multiplying or dividing machine | Direct multiplication/division instead of repetative addition/subtraction |
| 556720 | (none) | September 30, 1889 | March 17, 1896 | Bollee | - | Calculating machine | Four functions |
| 622470 | (none) | March 2, 1895 | April 4, 1899 | Hollerith | - | Adding and recording machine | - |
| 654181 | Universal Accountant Machine Co. | April 2, 1900 | July 24, 1900 | Rinsche | - | Calculating machine | Printing adding machine |
| 703188 | American Mechanical Cashier Co. | March 9, 1900 | June 24, 1902 | Dement | - | Cash register | Improvements |
| 703330 | (none) | March 13, 1902 | June 24, 1902 | Wiswall | - | Adding machine | Mechanical adder, looks like a Comptometer but is not one |
| 703785 | Paul Haack | July 2, 1900 | July 1, 1902 | Hamann | - | Calculating machine | - |
| 706375 | (none) | November 26, 1901 | August 5, 1902 | Baldwin | - | Calculating machine | Multiplication and division |
| 720086 | Mechanical Accountant Co. | June 17, 1901 | February 10, 1903 | Turck | - | Calculating machine | Not a Comptometer product |
| 726803 | Universal Accountant Machine Co. | May 9, 1901 | April 28, 1903 | Rinsche | - | Calculating machine | Keyboard locking during calculation, dual-color ribbon |
| 765774 | (none) | October 1, 1900 | July 26, 1904 | Goldberg | - | Calculating machine | Shows entered number before added to allow correction |
| 789099 | (none) | February 7, 1901 | May 2, 1905 | Lockwood | - | Adding machine | Printing adding machine |
| 809075 | Keuffel & Esser Co. | June 29, 1901 | January 2, 1906 | Rechnitzer | - | Calculator | - |
| 817450 | Walter L. Milliken, one-half interest | September 1, 1904 | April 10, 1906 | Shiek | - | Computing machine | Partially depressed key locks keyboard until key fully depressed |
| 823219 | (none) | October 20, 1903 | June 12, 1906 | Hensley | - | Calculating machine | Financial calculator to calculate daily interest and exchange problems |
| 823375 | (none) | February 2, 1905 | June 12, 1906 | Trinks | - | Calculating machine | Mechanical adder with rotatable disks, operating handle locked until disks are zeroed |
| 832666 | (none) | March 28, 1905 | October 9, 1906 | Hamann | - | Calculating machine | - |
| 890888 | (none) | January 24, 1907 | June 16, 1908 | Baldwin | - | Calculating and recording machine | Improved printing calculator |
| 938790 | (none) | March 29, 1909 | November 2, 1909 | Rein | - | Calculating machine | Selective resetting of feedwheels to zero with single operation of handle |
| 972360 | (none) | October 11, 1910 | October 11, 1910 | Graber | - | Calculating machine | Automatically perform four functions |
| 1011156 | (none) | June 29, 1911 | December 12, 1911 | Chase | - | Registering mechanism for calculating machine | Not a Comptometer product |
| 1011617 | Mercedes Bureau-Maschinen Gesellschaft, M.B.H | June 28, 1910 | December 12, 1911 | Hamann | - | Calculating machine | - |
| 1034565 | Austin Adding Machine Corp. | March 31, 1910 | August 6, 1912 | Austin | - | Adding, subtracting, and multiplying machine | - |
| 1136391 | Frederic L Huidekoper, Trustee of Washington, D.C. | August 28, 1911 | April 20, 1915 | Austin | - | Calculating machine | Improvements to 3-function mechanism of 1,034,565 |
| 1198487 | Rockford Milling Machine Co. | March 14, 1914 | September 19, 1916 | Sundstrand | - | Adding and listing machine | - |
| 1292513 | Autarit-Gesellschaft, M.B.H. | July 17, 1905 | January 28, 1919 | Rechnitzer | - | Calculator | Continuous motor drive operation |
| 1294507 | National Cash Register Co. | April 15, 1914 | February 18, 1919 | Martin | - | Registering machine | Direct subtraction, as distinguished from adding complements |
| 1297711 | Mays Accounting Machine Co. | April 30, 1917 | March 18, 1919 | Mays | - | Quotient registering mechanism for calculating machines | - |
| 1329028 | Rockford Milling Machine Co. | March 11, 1912 | January 27, 1920 | Sundstrand | - | Listing and adding machine | Mechanical simplification |
| 1329262 | (none) | March 20, 1915 | January 27, 1920 | Chase | - | Calculating machine | Not Comptometer - improved dual-register mechanism |
| 1409575 | (none) | July 26, 1912 | March 14, 1922 | Rechnitzer | - | Calculating machine | Starts multiplication as soon as entry of multiplier number begins |
| 1455555 | Rockford Milling Machine Co. | March 11, 1912 | May 15, 1923 | Sundstrand | - | Adding machine | Printer mechanism improvements, printing annotations |
| 1474230 | Monroe Calculating Machine Co. | November 23, 1920 | November 13, 1923 | Britten | - | Calculating machine | Improved operation of the crank handle |
| 1481487 | Rockford Milling Machine Co. | August 15, 1921 | January 22, 1924 | Sundstrand | - | Adding and listing machine | Printing adding machine with ability to print annotations |
| 1520438 | (none) | July 27, 1922 | December 23, 1924 | Pothig | - | Calculating machine | - |
| 1528018 | Mercedes Buromaschinen Und Waffenwerke | February 16, 1918 | March 3, 1925 | Hamann | - | Combined typewriting and counting machine | - |
| 1533119 | Powers Accounting Machine Corp. | December 24, 1917 | April 14, 1925 | Lasker | - | Cipher cut-out mechanism | Leading zero suppression for printing numbers |
| 1534242 | (none) | November 2, 1922 | April 21, 1925 | Odhner | - | Calculating machine | Eliminate springs in mechanism to return wheels to inactive positions |
| 1544806 | Monroe Calculating Machine Co. | January 16, 1922 | July 7, 1925 | Chase | - | Full-cycle stop for calculating machine | Full-cycle stop for hand crank |
| 1566650 | Monroe Calculating Machine Co. | November 21, 1922 | December 22, 1925 | Chase | - | Operating means for calculator | Reversing mechanism for negative calculations |
| 1583102 | Rockford Milling Machine Co. | September 13, 1920 | May 4, 1926 | Sundstrand | - | Adding and listing machine | Printing mechanism |
| 1643710 | (none) | February 18, 1924 | September 27, 1927 | Friden | - | Calculating machine | Multiplication and division by depression of a key |
| 1839138 | Fried Krupp Aktiengesellschaft | February 25, 1924 | December 29, 1931 | Breitling | - | Bookkeeping machine | - |
| 1845863 | Monroe Calculating Machine Co. | May 29, 1930 | February 16, 1932 | Chase | - | Calculating machine | Elimination of passive registration phase of a motor driven reversible cycle calculating machine |
| 1888161 | Monroe Calculating Machine Co. | January 7, 1926 | November 15, 1932 | Chase | - | Automatic control for calculating machines | Utilizes either build up or tear down method for division calculations |
| 1964211 | Monroe Calculating Machine Co. | September 22, 1932 | June 26, 1934 | Overbury | - | Calculating machine | Transfer of register contents to allow use of result in subsequent calculation |
| 2009010 | Marchant Calculating Machine Co. | March 30, 1927 | July 23, 1935 | Friden | - | Calculating machine | - |
| 2019900 | IBM | October 21, 1930 | November 5, 1935 | Fuller | - | Accounting machine | Improved mechanism with error correction for ten-key adder |
| 2058922 | Underwood Elliott Fisher Co. | August 29, 1933 | October 27, 1936 | Stickney | - | Computing machine | Multi-zero entry keys (e.g. 000) |
| 2061362 | Underwood Elliott Fisher Co. | March 16, 1934 | November 17, 1936 | Lentz | - | Computing machine | Multi-zero entry keys (e.g. 000) |
| 2100213 | Victor Adding Machine Co. | December 28, 1935 | November 23, 1937 | Garbell | - | Printing mechanism | Printer for adding machine accepts a card |
| 2108596 | (none) | July 17, 1929 | February 15, 1938 | Rudin | - | Calculating machine | Odner/pinwheel adding machine |
| 2153299 | Kooperativa Forbundet Forening u.p.a. | May 22, 1935 | April 4, 1939 | Dahlberg | - | Tens transmitting device for calculating machines and the like | Tens-carry |
| 2201713 | Monroe Calculating Machine Co. | September 30, 1939 | May 21, 1940 | Britten | - | Calculating machine | Improved multiplication mechanism |
| 2211736 | Marchant Calculating Machine Co. | December 18, 1933 | August 13, 1940 | Avery | - | Calculating machine | Mechanical improvements to eliminate carriage overshoot and reduce operating noise |
| 2214029 | Remington Rand Inc. | April 25, 1936 | September 10, 1940 | Mixer | - | Calculating machine | Mechanical accounting machine with card reader/punch that multiplies numbers on the cards and punches the result on the card |
| 2216659 | Marchant Calculating Machine Co. | June 12, 1936 | October 1, 1940 | Avery | - | Calculating machine | - |
| 2294083 | Friden Calculating Machine Co., Inc. | November 14, 1938 | August 25, 1942 | Friden | - | Calculating machine | Powered register zero/reset |
| 2311454 | Remington Rand Inc. | April 25, 1936 | February 16, 1943 | Mixer | - | Accounting machine | Method of zeroing accumulator wheels of the 2214029 machine |
| 2349769 | Underwood Elliott Fisher Co. | November 3, 1941 | May 23, 1944 | Sundstrand | - | Printing mechanism for adding and accounting machines | Dual ribbon mechanism for printing two copies |
| 2379877 | Monroe Calculating Machine Co. | November 13, 1941 | July 10, 1945 | Britten | - | Calculating machine | Improved mechanical multiplication/division utilizing short-cuts to reduce computing time |
| 2419760 | Monroe Calculating Machine Co. | July 13, 1945 | April 29, 1947 | Britten | - | Operation control means for calculating machines | - |
| 2427271 | Friden Calculating Machine Co., Inc. | October 27, 1941 | September 9, 1947 | Friden | - | Multiplier correction mechanism | - |
| 2525352 | (none) | March 7, 1946 | October 10, 1950 | Herzstark | Curta | Calculating machine | - |
| 2533372 | (none) | May 15, 1946 | December 12, 1950 | Herzstark | Curta | Zeroizing mechanism | - |
| 2538896 | Monroe Calculating Machine Co. | July 13, 1945 | January 23, 1951 | Britten | - | Multiplier magazine | - |
| 2544426 | Contina Buro-und Rechenmachinenfabrik A.G. | May 15, 1946 | March 6, 1951 | Herzstark | Curta | Visible setting control mechanism for calculating machines | - |
| 2566835 | Contina Bureaux-und Rechenmaschinenfabrik Aktiengesellschaft | April 27, 1950 | September 4, 1951 | Herzstark | Curta | Locking device | Crank lock |
| 2583810 | Clary Multiplier Corp. | March 13, 1945 | January 29, 1952 | Boyden | - | Accumulator state control positioning mechanism | - |
| 2681765 | Friden Calculating Machine Co., Inc. | November 7, 1949 | June 22, 1954 | Hopkins | - | Value indexing machine | - |
| 2794592 | Powers-Samas Accounting Machines Ltd. | May 26, 1953 | June 4, 1957 | Excell | - | Accumulator mechanism | - |
| 2826366 | Olivetti | January 10, 1955 | March 11, 1958 | Capellaro | - | Transfer mechanism for computing machines | Tens-carry |
| 2832283 | Olympia Werke A.G. | May 23, 1955 | April 29, 1958 | Westinger | - | Selecting and actuating means for arcuate type carriers | Print elements in an arc to improve printing speed |
| 2917231 | Clary Corp. | May 14, 1956 | December 15, 1959 | Stansell | - | Advancing-retracting means for calculating machine pin carriage | - |
| 2942776 | Underwood Corp. | December 29, 1955 | June 28, 1960 | Anderson | - | Actuating mechanism for ten key adding machine | Increase mechanism speed by driving as many parts of the mechanism as possible by motor, eliminating springs |
| 2945622 | Precisia A.G. | February 11, 1955 | July 19, 1960 | Heinze | - | Ten-keys keyboard for calculating machines | Mechanical improvements |
| 2992773 | Olivetti | April 17, 1958 | July 18, 1961 | Capellaro | - | Multiplication mechanism for adding machines | - |
| 3018044 | Underwood Corp. | December 29, 1955 | January 23, 1962 | Anderson | - | Tens transfer mechanism for an adding machine | Tens-carry |
| 3029014 | Olivetti | August 1, 1952 | April 10, 1962 | Capellaro | - | Differential mechanism for value entry, tens transfer and total taking | - |
| 3044697 | Monroe Calculating Machine Co. | November 7, 1958 | July 17, 1962 | Gang | - | Value selection and entering means for calculating machines | - |
| 3081938 | Walther Buromaschinen Gesellschaft m.b.H. | June 28, 1960 | March 19, 1963 | Walther | - | Device for controlling the position of the decimal point in adding and calculating machines | Decimal point key and mechanism to not require entry of trailing zeros |
| 3221644 | Precisia A.G. | April 5, 1962 | December 7, 1965 | Gelling | - | Printing device with zero suppressing means | Leading zero suppression for printing numbers |
| 3232223 | Olympia Werke A.G. | March 4, 1964 | February 1, 1966 | Thevis | - | Printing mechanism for business machines | Improved mechanism to reduce misalignment of printed numbers |
| 3315889 | Olympia Werke A.G. | September 21, 1964 | April 25, 1967 | Thevis | - | Control key arrangement for a calculator | Switch/lever changes behavior of storage/totaling keys |
| 3458124 | Citizen Watch Co. Ltd. | August 1, 1966 | July 29, 1969 | Piero | - | Printing device with zero-position selecting mechanism | Calculator printer mechanism |
| 3482775 | Citizen Watch Co. Ltd. | November 10, 1966 | December 9, 1969 | Piero | - | Simultaneous transfer mechanism for calculating machines | - |
| 3526356 | Olympia Werke A.G. | August 23, 1967 | September 1, 1970 | Hesse | - | Zero key locking arrangement for a ten key calculator | Prevents entry of leading zeros |
| AI229 | (none) | (none given) | April 19, 1859 | Castle | - | Improved arithmometer for addition | Additional improvement for patent 21941 |
| RE00551 | (none) | (none given) | May 11, 1858 | Castle | - | Prepared arithmometer for adding | Reissue of 18675 |
Last updated November 5, 2006
