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...