Herman Hollerith invented this machine for the 1890 U.S. Census. Operators punched data onto cards. A reader with spring-loaded pins was pressed onto each card—where holes existed, pins dropped through, dipping into mercury cups below, completing electrical circuits that advanced counters and opened sorting bin lids.
The 1880 census took 8 years to tabulate. With Hollerith's machine, the 1890 census was done in 1 year.