Silent Cops and Sleeping Policemen

A colloquial term for speed bumps placed across a road to slow down traffic is "sleeping policemen." This is apparently a variant of the term "silent cop" used to designate upright posts often set in the middle of intersections to channel traffic and prevent car jams. When was the term "silent cop" first used for these structures? According to one linguistic researcher, the term "silent cop" first appeared in 1914 in the Fitchburg Sentinel.

Have any other English words or expressions originated in Fitchburg? There's a good research question for someone.