Lightning Adding Machine: Simple Mechanism, Complex Origins

Patented in 1921 by Russell Hook of Grand Rapids, Michigan, the Lightning Calculator/Adding Machine was manufactured for more than 40 years and was one of the most popular and successful dial adders of the mid-20th century. Its development and corporate history, however, are extremely convoluted and emblematic of that of many commercial products of its type. 0:00 Introduction 1:05 Corporate/Development History 5:20 External Features 6:37 Operation: Addition 6:58 Operation: Subtraction 7:58 Clearing Bar 8:06 Calculator Co. Readout 8:45 Later Versions 9:34 Disassembly and Mechanism 11:06 Manufacturing Precision & Adding Machines 14:10 Outro SOURCES https://americanstationer.wordpress.c... https://americanhistory.si.edu/collec... https://www.jaapsch.net/mechcalc/ligh... https://patents.google.com/patent/US8... https://patents.google.com/patent/US9... https://patents.google.com/patent/US1...