Re: Medhurst

Hi Ralph,

The original papers are reprinted in "Wireless Engineer", February and
March of 1947 if you can find it.  They have only been out of print for 1/2
a century :-)  There is also a follow up letter in the "Correspondence"
section of the June issue.

Medhurst worked from the earlier attempts by Butterworth, Nagaoka and
Palerimo and made many very high precision measurements and corrected the
earlier works.  The equations are based on curve fitting from a large
number of measurements thus there is no real "derivation".  The papers
mostly dwell on earlier work and the pains they went through to make the
accurate measurements with the tools of the day.  The older experimenters
tried to base the capacitance on the turn to turn capacitance or even the
wire length :-o  Medhurst found that the physical dimensions of the coil in
space are what really defined Cself...

The original table from the March issue of the paper reprint is at:


This is the table all the other equations are based on...



At 02:41 PM 7/10/99 -0400, you wrote:
>Hi all,
>Would someone kindly show me the oft-mentioned Medhurst equation and its 
>Is there a text reference to it that is not out of print for a century?
>Cheerful thanks,
>Ralph Zekelman