The huge photographs are windows into the past. Easy to spend a lot of time studying each.
For example, this shot of the Atwater Kent manufacturing process. Why are women in the front and men in the back rows? Was it an assembly line? Did a worker hand her completed part to the worker behind? Perhaps men did the heavier work. All employees are white. AK did some automotive parts. Perhaps that's what they're building here:
http://www.shorpy.com/node/3670?size=_originalThis shot generated many comments on Shorpy: Women working and lots of men standing around (sounds good to me!). Note that some of the men are wearing ties. All have white shirts. Is that a conveyer belt running down the center of the bench? The fourth girl on left dared look at the camera. People are intrigued by her. Several noted the "bobbed" flapper hair styles made the rage by silent actress Louise Brooks.
http://www.shorpy.com/node/3534?size=_originalWhat are they making? One commentator on Shorpy knows his old radios:
"These are Model 20C compact radios. Assembled faceplates are on the shelf behind them. The set used the two individual sockets plus the 3 socket island and a large round rheostat. They are attaching components to the metal faceplates with brass bolts. After this, someone would solder the wiring on."
Go to the search box on Shorpy. Fabulous photos on just about any subject in remarkable detail. Several great shots of spark equipment including:
http://www.shorpy.com/node/10634?size=_original 
