In 1600, the British mathematician John Napier invented the logarithm
when he developed a multiplication table.
Forty years later the French mathematician, Blasé Pascal
built one of the first adding machines. Basically it consists of
a set of wheels assembled in parallel axis when changing their positions
were able to display the adding results in a sequence of windows
located in the cover of the machine. Fig. 354.
Therefore such early calculating devices were able to process adding
operations only.
In 1673, the German philosopher and mathematician Gottfried Wilhelm
Von Leibniz developed a calculation machine as know as the Leibniz
wheel, which execute in automatic way the four mathematical operations:
adding, subtraction, division and multiplication. Later on Charles
Xavier Thomaz improved the Leibniz’s concept by the development
of a device known as arithmometer. Certainly the Thomaz’s
device was the forerunner of the factory made calculators whose
industrial boom started at the end of XIX century only.
In spite of the great operational improvements involved in such
devices they could not be considered as a true analytical calculator,
capable to execute a sequence of pre programmed operations required
by a computer.

Fig. 354  The adding machine invented by
Pascal as known as "Pascaline" 
