Logarithm

The exponent of the power to which a fixed number, called the base, must be raised to produce a certain other number. Logarithms were invented by Lord Napier, a Scottish baron. They abridge greatly the labor of trigonometrical calculation, multiplication, division, involution and evolution of natural numbers being performed respectively by the addition, subtraction, multiplication and division of the corresponding logarithms. Lord Napier's base is 2,71828, and the common, constructed by Prof. Henry Briggs, is 10.