Guess what light this is...

[GEsoftwhite100watts]

Electronic instant-start ballast (or a magnetic slimline ballast?)
Blinks at at startup, and the stock lamps are usually (in my opinion horrible) halophosphate warm white but can be replaced with a cool white lamp

[A_lights]

undercabinent preheat fixtures

A fixture that takes a half circle fluorescent lamp is ------__________

[GEsoftwhite100watts]

Actually pre-heat circline adapters
Westy "circlarc" fixtures?

[A_lights]

Yep


T17 bulb with dents

[joe_347V]

Powr-Groove

GE roadway lighting fixture with a door mounted quick release ballast.

[GEsoftwhite100watts]

powr/bracket or powr/door
Flickers dimly in cold environments

[A_lights]

That would be those awful 60W Alto slimline lamps or 34W lamps

light with 3 brightnesses

[GEsoftwhite100watts]

3 way lamp
Lights dim greenish when well-used

[A_lights]

Mercury lamp with blackened arc-tube

The light that starts like Neon red and makes everything look black and yellow with  zero color rendering 

[GEsoftwhite100watts]

Low Pressure Sodium
Causes noticeable buzz in a whole room full of them...

[Mike]

Magentic rapid start fluorescent ballasts (or any magnetic ballast for that matter)

Known as Lucalox by GE.

[GEsoftwhite100watts]

High Pressure Sodium
Sylvania calls this lamp the "MetalArc"

[Mike]

Probe start metal halide.

Sylvania calls this lamp MetalArc Pro-Tech

[GEsoftwhite100watts]

NOT SURE... but let me guess CMH or PSMH
Cool white ones are slightly yellowish

[Mike]

Yeah Pulse start. CMH is Metalarc Powerball for Sylvania.

T12 Fluorescent lamps.


Introduced by Westinghouse in 1957 as the first "cobrahead" light ever on the market. They were used on davit poles when I-95 was constructed in RI in 1957 as well, though there are now 250W HPS M-250R2s on these poles, though the original poles from 1957 are still there, given they weren't hit.