Both American Slide Chart/Perrygraf and Datalizer Slide Charts remain in business as of 2012. The Ohmite Manufacturing Company, established in 1925, sold rheostats, fixed resistors, and adjustable ...

HARRISBURG, Pa. (WHTM) — Truth be told, most of us probably never thought much about slide charts and wheel charts, much less what it would take to be certified the world’s top collector of them.

Dale Rupert of Dauphin County has been collecting wheel and slide charts for the last 23 years and now holds the world record for his impressive collection. Since 2002, Rupert has been collecting ...

This circular slide chart consists of two plastic discs of equal size held together at the center by a metal rivet. The bottom disc is white, with a green logarithmic scale around the edge that runs ...