Familiar
with the machines of Pascal and Moreland, Leibniz envisioned
a calculator that could perform the four arithmetic functions
with speed and accuracy. He saw their value in business
and government, but his primary interest was science.

His machines, which he called his living bank clerks,
had two basic elements: a collection of pin wheels for
adding, similar to Pascal's, and a movable carriage that
could follow decimal places when multiplying. The two
sections were linked by stepped cylinders containing ridge-like
teeth of different lengths corresponding to the digits
1 through 9. Turning the crank that connected the cylinders
engaged the smaller gears above the cylinders, and these
in turn engaged the adding section.

Much to Leibniz's disappointment, his machines did not
meet his intended excellence. In fact, they were cumbersome
to operate and inaccurate.

It has been said that if Leibniz had lived longer, he
would probably have conceived the idea of a programmed
computer. That is pure supposition. But his invention
was a crucial step forward in the visionary phase of development.