Figure 1-11. The Von Leibniz calculator could do all basic operations easily.
e. The Colmar Commercial Mechanical Calculator (1820). The prototypes
built by Von Leibniz and Pascal was not widely used. The engineering techniques of
the period could not produce the precision required to make these machines reliable.
They remained curiosities until more than a century later, when Charles Xavier de
Colmar developed the first commercially successful mechanical calculator that could
add, subtract, multiply, and divide.
f. The Bollee Calculator (1887). Leon Bollee of France designed the first
machine to perform multiplication successfully by a direct method instead of through
cumbersome repeated additions.
Figure 1-12. Bollee's calculator used the direct method of multiplication.
g. Subsequent Advances (1890). A succession of improved "desk-top'
mechanical calculators followed, so that by 1890 the available built-in operations
included: accumulation of partial results, storage, reintroduction of past results, and
printing of results, each requiring manual application.