This key-driven non-printing adding machine has eight columns of metal keys, with nine keys in each column. It indicates totals with as many as nine digits. It is the sixth of eight production models ...

Dorr Felt, in some respects, was the Steve Jobs of his generation. Much as Jobs' Apple and Macintosh revolutionized how computers were used, Felt's comptometer changed how businesses kept their ...

IIIF provides researchers rich metadata and media viewing options for comparison of works across cultural heritage collections. Visit the IIIF page to learn more. This photograph shows Dorr E. Felt's ...

Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at www ...