Along with the CD 110.5 New Eng. Tel. & Tel. Co. / National Insulator Co. I just posted (click "Previous"), I thought it would do justice by posting a photo of its companion.

This was from the Tom Moulton collection that was sold in the late 1980s. It has the less common "straight across" skirt lettering along with segmented threading and National base embossing. It's got a cool streak of dark olive-amber near the top of the dome, too :-)