William Hart
The William Hart’s story had many twists and turns. He was a watchmaker, jeweler, businessman, and prolific inventor. Hart had quite a few patents for various instruments and devices, but it seems these devices were never used. That’s not the case however with his calculator, known as Hart’s Mercantile Computing..Read More
Louis Troncet
After the slide adders of Claude Perrault, César Caze, and Heinrich Kummer, in 1889 the French teacher, school director, inventor, scientist, and writer Louis-Joseph Troncet (1850-1920), created his version of this type of calculator, which he called Arithmographe. Troncet’s invention became so popular that the term “Troncet-type” is often used..Read More
Milton Hinkle
In 1877 Milton W. Hinkle of Memphis, Tennessee, invented a simple adding device, which he patented on 5 March 1878 (US patent No. 200911). The machine was somewhat similar to the earlier devices of his compatriots Jabez Burns, John Ballou, Joseph Harris, and Milton Jeffers. Only the patent model of..Read More
Peter Johann Backman
Around 1877 the Swedish public school teacher Per (Peter) Johann Bäckman from Stockholm invented an adding device, similar to the earlier calculator of Charles Henry Webb, and applied for patents in Sweden and Germany. The Swedish patent №205 of å framstäld räknemaskin för addition for nine years was granted on..Read More
William and Hubert Hopkins
The Hopkins brothers, William and Hubert, from Saint Louis, are the holders of more than 30 patents for adding machines and calculating mechanisms, mainly for 10-key calculators. Naturally, Hopkins’ remarkable contribution to the field of mechanical calculators had been started as early as the 1870s with the older brother, William..Read More
Johan Hellström
In the middle 1870s, the Swedish machinist Johan Fredrik Hellström devised räknemaskin (calculating machine), an interesting rounded adding device, similar to the earlier calculators of Braun, Leupold, and Hahn. The invention was announced in the Swedish press (e.g. in the newspaper Wermlands Läns Tidning on 21 June 1878). The calculating machine..Read More
Oberlin Smith and Valdemar Poulsen
Magnetic tape is the oldest memory media for computers, still in use today. A tape was used for the first time to record data in 1951 in the Mauchly-Eckert UNIVAC I computer and is still in use today as a cheap and reusable archive media. So, who invented magnetic recording,..Read More
Ramón Verea
In 1878 Ramón Silvestre Verea Aguiar y García (1833-1899), a Spaniard, and newspaper publisher in New York, patented a direct-multiplying calculating machine, which seems to be the second patented machine of this type in the world (after the machine of Edmund Barbour), ten years before the first popular direct-multiplying machine..Read More
Reuben Rodney James
On 5 November 1878, Reuben Rodney James (1826-1904), a farmer from Rising Sun, Indiana, took out a US Patent №209690 (see the patent of R. R. James) for a simple adding machine, similar to the earlier calculators of his compatriots Jabez Burns, John Ballou, Joseph Harris, and Milton Jeffers. It..Read More