Concept
Version 13
Created by Boundless
Automobiles, Airplanes, Mass Production, and Assembly-Line Progress
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"Safety Last!."
https://en.wikipedia.org/wiki/Silent_film#/media/File:Safetylast-1.jpg
Wikipedia
Public domain.