Pitted Against The Pendulum

A lot packed into this message! The best way to start to tackle the Cosmic Void scroll message here is to break it down into its three related puzzles, to make the complexity more manageable:

There was one outstanding pendulum in DC - the Foucault pendulum in the old Smithsonian Museum of History and Technology, opened in 1964. As a matter of fact, the building was designed with this exhibit in mind, it had a magnificent space dedicated to it - it had its own large space covering all three floors. It was THE central landmark of the first floor of the museum, people would head there first, then break up and say, "let's meet back at the pendulum at Noon!" - and check to see how many pegs had been knocked over.

The Foucault pendulum demonstrates that the Earth rotates by allowing a pendulum to rock back and forth - the inertia of the pendulum system keeps the pendulum moving in the original plane, while the earth rotates around it. The pendulum bob knocks over little dowels in its path, keeping track of the slow apparent precession of the bob around the available circle.

The pendulum is not there any more! In 1980, the museum was renamed The National Museum of American History - and the management started to note that the pendulum was neither American nor "historical" (in the political/national sense). They managed their first action against it, by shortening it to 2 floors in 1989, allowing them to arrange a first floor space that could have alternating marquee traveling exhibits.

The final assault was to "share" the space on the third floor with the truly grand exhibit of the Fort McHenry US flag - the flag Francis Scott Key wrote the "Star Spangled Banner" about. In 1998, they bigfooted the pendulum out, to give the flag all the room. In 2006, the museum was extensively remodeled, so all trace of the previous emphasis was erased.

The experience at the LA museum may have influenced their decisions - a drunk decided to jump over the barriers to the exhibit to try to ride their pendulum plumb bob like a swing. He broke the wire holding the pendulum, and the bob broke the immaculate marble flooring beneath. The falling wire could have cut into him badly, but he had the luck of the impaired and escaped injury.

Even though the pendulum is no longer there, and the internet does not explicitly detail the timing of the exhibit, we know enough about this to solve for Roger's first question! - next time.