In a message dated 97-12-09 11:11:30 EST, you write:

<< No, it's sensing the electric potential that naturally exists in the
 atmosphere, the same one responsible for lightning. With a sensitive
 instrumentation amp you can measure the voltage difference between your
 feet and your head (usually a couple hundred volts over six feet).
  >>

Is higher potential "always" up??

Mark A. Corio
Rochester MicroSystems, Inc.
200 Buell Road, Suite 9
Rochester, NY 14624
Tel: 716-328-5850
Fax: 716-328-1144
http://www.frontiernet.net/~rmi/
****** Designing Electronics for Research and Industry ******