"Steve B" wrote in :

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=is ch&sa=1&q=cartographer+planimeter&aq=f&aqi=&aql=&o q=


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Tegger