I'm old enough to remember steam locomotives. A branch line separated two sections of my grandfather's farm, and I recall picking up huge chunks of coal that fell off overloaded tenders, some of them easily 12 inches or more in diameter. Coal was the common fuel in those days, and we used stove coal in the furnace. The water heater was fired with pea coal.

This is bituminous (soft) coal, a higher sulfur coal -- smokier and more ash. There were different grades of soft coal, and this is most likely from the West Kittanning B seam. A very high heat to ash coal. The steel mills just ate this stuff up. Soft coal was mined in the western part of Pennsylvania along with West Virginia and Kentucky down the Appalachians, hard coal specifically to eastern Pennsylvania.

I was intrigued by the different sizes of coal in the various cars, so I looked it up and discovered the following (from smallest to largest, by name of size): barley (size of coarse sand), rice (pencil eraser), buckwheat (dime), pea (quarter), chestnut (golf ball), stove (baseball), and egg (softball). But I’m still a bit confused because those chunks in the cars on the left are certainly bigger than softballs.

This has nothing to do with modern claims of cleaner (less polluting) coal. I did some research and this is about cleaning the dirt and detritus from the dirty coal. It looks cleaner but still burns dirty!

This is why nobody cared if they smoked cigarettes back then.