borrowing from tomorrow

[kowalskil@alpha.montclair.edu]

On February 19 Dewey Dykstra wrote:

> Exactly how is this [the existence of two kinds of charge is established? 
> I'd be interested especially in how this is accomplished.

A very good way of doing this (with strips of scotch tape) is described in
"Electric and Magnetic Interactions" by Ruth Chabay and Bruce Sherwood
(John Wiley&Sons, 1995.) 

> I'm wondering exactly whose logic and whose continuity is entailed in this
> logical continuity. I know that I and many others for many years (decades?
> centuries even?) have attempted to use this principle, but it does not seem
> to be all that effectve at least in terms of changes in student
> understanding.  I wonder if our logic and our continuity is not what's
> called for here.

   Please elaborate on your last sentence.             Ludwik Kowalski