I don't mind babbling, so here goes: since the incandescent bulb was invented in New Jersey, maybe PRR rejected it as "NIH". Also, the photo could be an optical illusion. That is probable. As a retired soldier, I know we required the use of headlights on our vehicles "en convoy" in CONUS. I would, often times, stand at the side of the roadway to ensure that the lights were on as the convoy 'moved out'. If they weren't, pointing each index finger at ones (two each) eyeballs got the driver's attention and the lights came on. I have used this as a signal trackside and it works! Lack of headlights may be a result of "operator headspace" or an engineer/motorman busy 'texting'. Don't poke your eyballs out!
As far as "ancient history" goes, maybe some of those practices of 'running dark' were hold-overs from the WWII blackout silliness and the rule books weren't updated for a while. Perhaps un-shrouded headlights had their bulbs removed. Dunno, but I'm only 70 y-o-a. I'll be 71 next week. Say "Happy Birthday", or else....
Hays
