Mapparium's whispering-gallery effect

The Mapparium is a three-story, stained-glass globe built in 1935 inside the Mary Baker Eddy Library; visitors stand on a glass bridge through its center. The globe produces a pronounced whispering-gallery acoustic effect: a whisper spoken at one side can be heard clearly on the opposite side due to the spherical geometry and reflective surfaces. The installation and its acoustics are documented by the library and are a long-standing piece of Boston cultural lore.