| Ramon de Verea's Adding
Machine (1878) |
 |
| "This is the model of the machine that
Verea submitted
to the United States Patent Office. (Source: G.C. Chase, History of Mechanical Computing Machinery", Annals of the History of Computing, Vol. 2, No.3, July 1980, reprint of Proc. ACM, 1952)" Andries de Man |