Thank you, nice data. A little tricky to extract from the .pdf, but no matter.
So if you subtract the free air gradient, you get a nice (if somewhat bumpy) slope from the top of the building to the bottom, with gravity being higher at the top. Since we don't know the zero reference (the gravity at that spot if the building had NOT been there) we cannot deduce the center of gravity, however, your measurements are EXACTLY as predicted by established gravity theory:
At the top of the building, you are exposed to the gravity of Earth + the gravity of the building (but - the gradient from altitude).
At the bottom of the building, you are exposed to the gravity of Earth - the gravity of the building.
Between those two points, there is a continuous gradient which crosses zero in the building's center of gravity.
Nice work, Bjarne. You have just disproved your own thesis, but a true scientist accepts that and moves on.
Thank you for playing.
Here is the differential gravity measured by Bjarne's team, when corrected for elevation. As you can see there are a few bumps, but they can be due to local mass concentrations. We don't know exactly what is in that building.
-0.277
-0.467
-0.642
-0.562
-0.470
-0.395
-0.315
-0.225
-0.151
-0.079
0.004
0.073
0.151
0.221
0.294
0.359
0.425
0.498
0.563
0.634
0.705
0.766
0.825
0.896
0.968
1.050
1.118
1.190
1.278
1.345
I will leave it as an exercise to the masochists to calculate the mass of the building from this.
Hans