I didn't find much in the way of glass on my flea market trek yesterday, but these porcelain strains eased my "tension." 8^) On top is a large (4 ½" x 3 ¼") crude dark brown (Thomas?) johnny ball strain with some chipping/flaking along the sharp edges. Biggest one I've seen. On the bottom is what I assume to be a strain insulator. It's 15" from end to end and weighs in excess of five pounds; the heavy-duty end caps appear to be cast brass; and the white porcelain shaft seems solid. There are no markings or other types of identification anywhere. The seller had two, but considering the price he was asking and my not knowing for sure what they are, I bought only this one. If someone tells me that they're rare and valuable, I'll go back and try to get the other one, too. 8^P
Thanks for looking. Comments/inquiries welcome.