They are called insulators and collectors lovingly refer to them as “jewels of the wires”. They were first invented to use on telegraph wires in the 1850’s. As technology progressed they were used on all telephone and electric lines to “insulate” the wooden poles from the electricity traveling through the wires. The pressed glass was non-conductive, cheap to manufacture and threaded onto wooden poles. In the early 1900’s they cost between $0.38 and $1.00 each and could be ordered in different colors to distinguish different currents or different company’s lines on the same pole.
There are tons of people out there who collect insulators and some rare colors or shapes can sell for $8000 to $15000! See more examples http://www.insulators.info/photos/
Here at Conant Metal & Light we think the dime-a-dozen clear and aqua versions make awesome lamps, pendants and wall sconces. Not only are we finding a new use for vintage items, but we are paying homage to electricity’s history. Check out our prototypes and please tell us what you think.