26 MEASURING AND ANALYZING APPARATUS-NAMELY, ANALOG COMPUTERS, AND MEASURING AND ANALYZING PARTS AND COMPONENTS SOLD SEPARATELY FOR USE IN ANALOG COMPUTERS, NAMELY, OSCILLOSCOPES, METERS, AND COMPUTING CIRCUITS, INCLUDING ADDERS, COMBINORS, AVERAGERS, INTEGRATORS, DIFFERENTIATORS, SQUARERS, LOGARITHM AND ROOT COMPUTING CIRCUITS, EXPONENTIAL CIRCUITS, DIVIDERS, MULTIPLIERS, AND LOGIC CIRCUITS