The fact that the logarithm function converts the multiplication of two 
     numbers to the addition of their logarithms:
                        log(uv) = log(u) + log(v)
     was discovered by John Napier in the 1600's.  This property of logarithm 
     was used to invent the mechanical device called the slide rule and it      
     allowed scientists, engineers and navigators to perform multiplication 
     and division much more quickly than by hand.

     Slide rules were the portable calculators of their age (approximately
     300 years from about 1700 to 1975).   

     The picture shown to the right is of the astronaut Buzz Aldrin (2nd man    
     to walk on the moon in 1969) using a slide rule to perform calculations 
     related to a spacecraft midcourse navigation correction.

     The introduction of electronic calculators in the 1970's made slide rules
     obsolete and students today are often not taught well the importance of 
     the fact that the logarithm function converts multiplication to addition.