I've seen E&J sidelights with a brass top like the Jno Browns and some where the whole top appears to be brass. I've only seen this in pictures so I can't tell if it's all brass or somebody painted the steel a brass color. Also the part where the lamp fits on the bracket.
There are many variations of the 1909-14 E&J side and tail lights.
E & J variations
Use a magnet that will let you know if it's brass or steel. Generally speaking the later mounts were brass covered steel.
There are more variations than in the noted article, also other makers (Brown etc) had lots of variations too.
The 13/14 lamps are supposed to be painted steel with brass trim [chimney & 1/2 font] but I have some with brass bodies and steel trim painted all black.
John, have you found that b/b E&J cowl lamp for our trade yet?