Before I continue, I need to give a shout out to Nick Pyenson - Nick initially forwarded Dr. Smith's emails to me, and this project has wasted a third of my summer. No, but seriously, thanks.
After putting the top jacket on, then came the problem of how exactly I was going to A) undercut it and B) actually flip it over. Normally, a trench is cut and then the pedestal is undercut from all sides leaving a pillar of rock underneath, which you can subsequently eliminate and then flip the jacket over. However, this jacket was far too large to do conventionally. And I couldn't really fit tools in all the way around the jacket to really undercut it from all sides.
So, in cases like this, go tunneling! I started two holes and dug and dug until they connected, and then widened them into a larve cavern underneath, and then added a hole on the other side. Problem was, this jacket was so large, I eventually couldn't reach the back wall with my rock hammer, and had to use my large estwing pick to scrape away underneath. Tunneling, by the way, is a good recipe for bloody knuckles.
Here you can see more of the tunnel. Aside from these two small columns, the back part remained as a large pedestal in back; the jacket stuck out from this like a surfboard with two pillars. Once I cut the pillars, I figured it would break the pedestal, and tilt forward.
The moment of truth! This was on the heavy side. Well, nothing happened - the left pillar remained still, but I figured it would fail if given this much weight. Apparently not, however - it just hung like this for several minutes.
When I cut through the other pillar, it shifted almost imperceptibly forward, but I knew at that instant that I had been successful. Then, I found one of the construction workers to help me flip it over and complete the jacket.Here's what it looked like - you can see the overhanging plaster; that's where the crack formed, leaving a little bit of the pedestal back in the hole, which I'll excavate in a separate jacket.
Voila! Here's the completed plaster jacket. It's pretty heavy.