I just recently found a cute little computer book called "I can learn about Calculators and Computers" by Raymond G. Kenyon, Harper & Brothers, 1961 112 pages. The chapters are entitled: How Early Man Counted and Computed The Story of Modern Computers Construct Your Own Calculators and Computers - - Oriental Abacus - John Napier's Bones - Slide Rules - "Stepped-Wheel" Calculator - Digital Computer - Analog Computer Materials used consist of wood, wire, D-cell batteries, flashlight bulbs, potentiometers, etc. Remember wooden cigar boxes? Regards, --Doug ========================================= Doug Coward @ home in Poulsbo, WA Analog Computer Online Museum and History Center http://www.best.com/~dcoward/analog =========================================