1887 - Comptometer patented by Dorr Eugene Felt (1862-1930), the first practical and commercially successful adding machine, 1888 - manufacture of comptometer begun by Felt

1889 – the Felt and Tarrant Manufacturing Company of Chicago established by Dorr Eugene Felt and Robert Tarrant;

1957 - the Felt and Tarrant Manufacturing Company changed its name to Comptometer Corporation;

1960 - Comptometer Corporation sold its UK operation, including the right to the Comptometer name in Britain, to Control Systems Ltd. (the parent of the Bell Punch Company) who merged with own company to form Sumlock-Comptometer; The Comptometer Corporation then contracted Control Systems to get Bell Punch to make all comptometer machines in England that were then shipped back to the United States;

1961 - Comptometer production ceased in Chicago; machines from Sumlock were marked with the Comptometer name