On Apr 17, 3:48*pm, Tegger wrote:
"Steve B" wrote :

I need one of those pen contraptions that you roll over blueprints and
aerial photos that then give a numerical value to the distance traveled..
What are they called, and what's a good supplier of them?

I believe you're thinking of a "planimeter".

http://www.google.com/images?um=1&hl=en&safe=off&biw=1728&bih=885&tbm...

--
Tegger

The OP is looking for a "wheeled scale", not a planimeter.

A planimeter is for "measuring" (actually, mechanically summing) the
area enclosed by a perimeter.

btw... if anyone needs one, I'd be willing to loan mine out. I
bought one on ebay several years ago, I actually needed one.

cheers
Bob