
 How Did a Slide Rule Work? 
  Thus, 4 is 2 to the second power, 8 is 2 to the third power, 16 is 2 to the fourth power, and 2 is the logarithm of 4 to the base 2, 3 is the logarithm of 8 to the base 2, and 4 is the logarithm of 16 to the base 2. 
  This makes them convenient for doing arithmetic, because the integer part of a common logarithm indicates where to put the decimal point, and the fractional part is the same for the logarithm of 326, 32.6, or 3.26, so that tables need only contain the fractional part of a common logarithm. 
  The L scale is a uniform linear scale, and is used to read off the fractional portion (or mantissa) of the common logarithm of numbers on the C scale. 
 www.quadibloc.com /math/slrint.htm (1438 words) 
