This insulator was discovered along the Potomac Path, which followed the old Telegraph line in the park. Insulators were developed over 100 years ago for use with telegraph lines. They were used to keep lines dry and to cut down on loss of current. Present-day Route 1 basically follows the old Telegraph line which passes through the park. Inscription in raised glass carries he number 7.
You are all set!
Your first Culture Weekly will arrive this week.