Help identify

[DLA]

Light bulb Grandma used as night light. I received it in 1978 after she passed away. Mom thought she bought it at a yard sale about 1940, it still works. Tipped bulb, Edison base with porcelain, paste connectors, spiral filaments' tall glass pedestal with the letter "Z" molded into the base, lightly darken (assume carbon and vacuum) bulb. For me to pass down to my kids, I need to know all I can.

[DLA]

Found a light bulb in the Smithsonian that is nearly identical in design construction except it has white plaster like insulating material. I did not see the "letter Z" on stem. Label on bulb "Independent" brand. see attachment

[DLA]

Found the "Independent" carbon lamp was established in 1895. I still can't find my bulb or where "Independent" carbon lamp is located. Source for this is Chicago Museum of Science & Technology.

[DLA]

Found a company by the name of Independent "New Light" Company located in Schenectady, New York (where General Electric was located in early 1900's) that is listed as still active today. No info how to contact them, though I doubt they are even aware of their beginnings and no online info of its origins.