Everything you never knew you wanted to know about the Mercury Project
Was there a transparent cover over the periscope
From RixWiki
Peter Johnson has taken many photos of Sigma 7 as it currently resides in the Astronaut Hall of Fame Museum. He says that "as displayed, there is a clear panel mounted above the periscope display. Was this original equipment, or added later? To me it looks original, but it covers some of the adjustment knobs, which doesn't make sense."
On Dec 11 2004, Peter took more Sigma 7 photos, including this one of the periscope screen. It appears that the clear cover is original equipment. The cover is hinged at the top, and has spacers to hold it off of the screen and knobs at the bottom. It also has a large binder clip on the right side. Peter opines that "Schirra did not think the 'scope was necessary, so perhaps he created a useful work surface over it".
Update 18 March 2005
I received an e-mail yesterday from David Weeks with information about this question.
Wally Schirra had a book signing recently in San Diego, David wasn't able to go but Manny Gutsche was. David asked Manny to ask Wally about the cover over the Sigma 7 periscope.
Manny reported that Wally claimed the plexiglass over the periscope was done after MA-8. He thinks for protection during display. He would put charts over the periscope, but did not have a board to place them on.
Manny showed Wally the close-up photo Peter shot of the periscope as a visual aid. According to David, Wally's answer confirmed what David thought when he saw Peter's photo, which was that installation didn't look "anal" enough to David for a NASA pre-flight install.
