Why is the rear light lens blue color on the brass lights?

I am writing comments on pictures and am explaining the red and clear, but why the blue?
Thank you in advance. Bob

I thought it was a hold over from nautical lanterns, to identify which side you are passing on to avoid nighttime collisions

Sounds good Ed, thanks. I'll use that one.

Boats have a red light on the port side and port wine is red. Red means stop. They have a green light on the right side and that is the starboard side. That name comes from the steer-board or the oar that was used on the right side of a boat to steer it. Look at an Italian gondola, the are propelled and steered from the right side. You have the right-away over boats to your left because they see a red light. Boats on your right have the right of way over you because you are showing them a green light.

I have had many early brass cars with green lenses but never saw a blue lens. Could be age changed the color. The early brass lamps usually have three lenses. A clear one on the right to illuminate the license. A red lens facing the rear, and a green lens facing to the left to let folks waiting on the left to know that they may proceed as the green light passes them.

The 1925 Studebaker I had years ago had a green jewel in the right cowl lamp, and a red jewel in the left cowl lamp. Same reasoning. Although they were really too small to be practical.
Many early automobiles were steered using a tiller. Another nautical influence.

I forgot to mention that the port is called that because the steering board was on the right side or Starboard side and the left side was where they docked in port thus it is the port side.

Our traffic lights are red and green but the yellow is confusing because a submarine at anchor on the surface displays a yellow light at each end. hmmmmmmm does yellow mean danger slow down?

Robert - Conjecture on my part here, but as a 4th generation railroad man, I believe I can answer your question regarding the blue lens. My reasoning here comes from a bit of knowledge I have in regard to railroad marker lamps that used to be used on the cabooses. Those kerosene RR marker lamps always had red and blue lenses too, and I can tell you why. The actual color of RR marker lamps in actual use after dark is red and green. Yes,....GREEN! That is because the actual flame from the kerosene burner is yellow. And a yellow flame which shines through a blue glass sense shows GREEN. I have seen many of the old RR caboose marker lamps that have been electrified and used for decorative purposes, and when illuminated, they always show a red light and incorrectly, a blue light, and this is because they have been electrified with a clear or white frosted incandescent bulb. All that needs to be done is to replace the clear or white frosted bulb with a YELLOW bulb, and the illuminated blue lense will appear as green as grass. And as your beautiful brass tail lamp was an oil-burning lamp Robert, that yellow flame would also make your blue lense appear green too!

Why, heck! All you had to do was to ask a sharp little 1st grader about it Robert, and he or she would have told you that blue and yellow makes green! Ha,ha,....jus' jerk'n yer' chain Robert,.....hope this helps,.......harold

That darn auto-correct changed my word lense to sense! I did proofread but missed that one! Sorry,.....

Actually, I'm not sure now if it's "lense" or lens,....oh well,.....

Harold, that makes perfect sense! Thanks for clearing that up and the interesting factoid - and by the way, you have the worlds best job! Who wouldn't want to work for the Railroad riding the rails!

I know the one on my 11 is blue. Good job explaining that one.

yellow and blue makes green! At least that is what the sandwich bag commercial taught me years ago!

All joking aside,I really appreciate this thread as I have often wondered what the purpose was. I have green lens that fit clearance lights from old semi trucks and I have blue lens that fit them as well. Never did understand what they were for.

Bill - I don't know about that,...."worlds best job" thing! Yes, I had my share of "riding the rails" but it was probably not quite what you think! I retired 14 years ago from the Union Pacific RR Police Dept. as a Sr. Special Agent. Also known as a "cinder dick", "yard bull", "railroad detective", "gumshoe", and several other names we were called behind our backs that I'd rather not admit to!

Actually, I guess you're right in a way, as I really do have a great job now,...as a RETIRED RR cop! Ha,ha,.....harold

I'm confused, Wouldn't a red lenses and a yellow flame make orange?😃

Frank,
I spent 4 years in the U.S.Navy (1968-72). Most of that time was on a submarine. I was a Quartermaster, so in addition to my navigational duties it was my responsibility to assure we were displaying the proper lights when required, both at sea and in port (anchored or moored). I've never heard of a submarine displaying a yellow light at each end when anchored, or at any other time for that matter. Is this something new? It seems odd that a submarine would be required to display anchor lights that are different from any other ship.

Just to confuse everybody further...
http://www.bosunsmate.org/seamanship/lights.php

Henry, It is posted in Chapman's book and I saw a speedboat run into a submarine anchored in Avalon Bay and it rammed the sub which was displaying the yellow lights. Perhaps it was inland navigation rules. I don't know, but it in in the Chapman's navigation book. The boat was a mess.

John Brown 115's are blue glass on the driver's side but when you light the burner they are a bright blue glass and seems like we still have the question.

Ken in Texas

Well, back to the Railroad angle: A blue light indicates a piece of equipment being worked on and it is NOT to be approached or moved without a release from the person who hung the blue light.
I doubt this has anything to do with the automotive use!!

David, you also had to have a derail in place along with the blue light or flag. From a former "car knocker" KGB

Some insight, from last century...


Motor Review March 1902

Kieth, True, true--but I wasn't getting into the "fine print" of it all! I never worked for a "real" railroad, just railroad museums! Although Solano Railcar passed me off as a WP Car Knocker to get a "hospital train" of friction-bearing equipment on the mainline. That was a crazy trip, most of the cars had been FWSed (Fixed with Stencil--means you stencil the trucks that the brakes & bearings have been serviced and tested, but in reality all that was done was to see if they actually moved when the air was released--no actual repair work done! Oh well, train made it to the museum, and the statute of limitations has passed! Some of those cars hadn't been moved in decades! I doubt it could be been done today--life was really simpler then.

Here's a couple of photos, one with a LED torch,one with oil burner - it definitely looks green around the oil flame.




This one of a pair I have, 1 right hand, 1 left hand. The RH one is of course for a RHD car, so the blue/green lens shines to the right, not sure where that leaves us on port & starboard.

Slightly OT, I was once trying to buy a pair of French sidelamps, but the LH one was different, it had green chevrons (like a Citroen badge) in the LH side. When I said they weren't a pair, the French seller said No, all his lamps were the same. He explained that it was to do with 'priorite au droite' (Give way to the right).

Well into the late 20th century, you could be bowling down a main road in France when a local would shoot out of a side road into your path, and you had to give way to him.

In the 20s, looking across the fields to your right you might see lights approaching on a side road. If it was horse-drawn (therefore slow) the light would be plain. If it was a motor vehicle, you would see the chevrons and expect it to be moving faster.

Here's the pair of E&Js.