I am teaching a class on telephone wiring and was wondering if you could answer this question.  Why does the gauge # decrease as diameter increases in wires?  Nobody seems to know, thanks, Jon

In general a wire size gauge number corresponds to the number of operations involved in drawing a wire, a larger figure representing more operations resulting in a smaller diameter. The American Wire Gauge (AWG) copper wire gauge is a logarithmic scale base on a wire's cross section, each 3-gauge step in size corresponding to either a doubling or halving of the area.  Note that the doubling of a wire's cross sectional area halves its' resistance.  In the Colorado Springs Notes 1899-1900 Tesla refers to wire size using the "Brown & Sharpe" wire gauge which is equivalent to AWG.