Perhaps best known for inventing Logarithms, John Napier had a wide reputation for other interests as well. These ranged from theology to farming to scientific discovery to invention. It is with his work on logarithms that enabled him to create a simple, yet powerful aid to calculation. This calculating device was made of several sticks (made from ivory or bone) marked with numbers on them. By moving the sticks into different positions complex multiplications or divisions could be reduced to simple addition and subtraction operations. Follow these links for more details:
Gottfried
Wilhem von Leibniz (1646-1716)
The Leibniz caclulating machine
The first calculating machine which was produced in large numbers was invented by the Frenchman Thomas de Colmar in 1820. This "Arithmometer" was the first of many mass produced calculating machines in the nineteenth century.
The next major step was the change to a "pin wheel" mechanism by a Swedish inventor Wilgodt T. Odhner. This site has more information on de Colemar and Odhner.
To operate an 1885 Felt & Tarrant "Comptometer" adding machine over the Web visit this web site
If you want to know how these calculating machines worked visit The Museum of HP Calculators
Timeline for Early Mechanical Calculators
Take a look at this detailed biography by J.A.N. Lee
His first design was the Difference Engine. Originally designed to calculate new error-free mathematical tables, the Difference Engine was never finished. While in the midst of the designs and prototypes for the Differen ce Engine, Babbage envisioned an even more useful calculating machine, the Analytical Engine.
Like the Difference Engine, Babbage never finished his Analytical Engine. This time Babbage did not abandon his work, rather his financial supporters withdrewn their money. If Babbage had been a better manager of his project and the funding, he may have been able to complete a working model of the Analytical Engine in his lifetime. When he died in 1871, his great dream seemed to die with him.
Many people have never heard of Charles Babbage, but his ideas were certainly revolutionary. Nearly 100 years before Howard Aiken (inventor of the Mark I) and Konrad Zuse (creator of the Z1) were to successfully build their general purpose calculating machines, Babbage had envisioned a machine with a "central processing unit" (called The Mill by Babbage) and a seperate area to store the data (The Store). His choice of punched cards to program his Analytical Engine would prove to be another leap foreward.
Here is a great Web Page about Charles Babbage written by seven year old
J.A.N. Lee