The 13th stone or the "Great Tree" or the location of the next 'great event' in NYC?

Is it the mysterious stone next to the "Great Tree" that obscures the view of Lower Manhattan from WD Gann's grave or is it the "Great Tree," itself.  Or neither.  Or an indication of the next great event in the life of NYC?  On my third visit to Green-Wood Cemetery, I took GPS coordinates for both the hypothetical 13th stone and the "Great Tree."  This is a long one.

On my first visit to WD Gann's grave on June 21, 2015, I sensed the perfect alignment of a row of stones that were facing just as his while the stones behind his and on the hill to the left and right were not so aligned.  When I identified those stones in Google Earth, I noticed the stones in front of that line of stones (there were 7 stones aligned that I name 1 through 7) were also aligned. Stones 1, 11 and 7 formed a triangle perfect right triangle:

Left above is an isosceles triangle formed of stones 1-7-11 of the 12 stones and on the right is a diamond comprised of back to back isosceles triangles.  I've proven the map of those triangles and they're pretty darn close to perfect.  The 12 stones and component triangles they form are what I've named the "WD Gann Gravestone Geometry" or GGG.

The triangle is bounded by stones that are misaligned relative to the orientation of the 12 stones of the GGG.  Below insert left you will see yellow, green and orange arrows that are stones that are misaligned with the enumerated 12 stones of the GGG; they are boundaries between the 12 stones and all others in this vicinity of Green-Wood Cemetery (GWC).  The GGG has very little relation to the map of section 129 (Mason's section) based on the map at the bottom right of the following insert.

I've thought there was a 13th which is located, hypothetically, at the apex of the insert above right.  The green lines forming the triangle reach an apex where I believed the stone that is right of the Great Tree facing from Mr. Gann grave towards the Great Tree.  I was wrong.

I visited GWC twice since that first visit and based on the second visit (August 2, 2015), I formulated the "13th stone" theory.  Obviously I knew I had to visit again and did so on November 15, 2015.

On that third visit I had my daughter and son-in-law with me (errr, I was traveling with them) and I tried to keep the time to a minimum for their benefit.  Among other investigations, I took and screen captured 14 GPS readings; one for stones 1-12, one for stone 13 and, at my daughter's behest, one more at the trunk of the "Great Tree."  Keep in mind, that small coin type medallion is about 7 feet off the ground and is inscribed "E1942."  My interpretation, an endowment was gifted in 1942 for the care of, at least, that tree.  WD Gann purchased lot 37747 for Sadie Gann's internment in 1942.  Here's the tree and GPS coordinates:

Of course, the hypothetical 13th GPS reading I took was the 13th stone that is about 3 feet to the side of the "Great  Tree."  The hypothetical 13th stone cannot be seen under the tree from Google Earth just as Lower Manhattan cannot be seen from Mr. Gann's grave...the "Great Tree" is truly magnificent.  Here's the mysterious hypothetical 13th stone and GPS shot that day.  Interestingly, notice the stone has been moved sideways, askant of its base:

We have a problem.  The 13th stone lies visibly outside the location where I'd hypothetically plotted the location of the 13th stone.  The blue vectors at the top of the triangle in the below insert (left) is where I thought the 13th stone would be.

But the GPS coordinates I took on November 15 simply did not comport with the triangle that is fitted to gravestones 1-7 and hypothetical 13 (left above).  The GPS measurements taken from my cell aren't the same as the measurements from Google Earth.  They are different by several feet; I would expect that difference to apply, proportionately to every measurement taken.

So, the measurements of the two systems aren't the same, at least the cell phone measurements must be consistent amongst those taken on November 15.  In the right frame of the above insert plotting of stones 1-7-13 doesn't  give me a recognizable triangle (sides of 17.5, 25 and 26.8 yards).  Not isosceles, not right, not equilateral.  The hypothetical  13th stone seems invalid.

What about the "Great Tree?"  Visually, when you're standing there, there's only about 3 feet between it and stone 13 and maybe 5 feet when you measure from the center of the trunk to the center of the stone; not enough to make the above an isosceles triangle.  The Great Tree as the apex of a meaningful triangle seems very unlikely as well.

So is there redeeming value to the investigation of the 13th stone and the "Great Tree?"  Let's plot the cell phone coordinates of the "Great Tree" and stone 3 (stone 3 is that of Mr. Gann) and see if anything pops up.  Here's stone 3 and the GPS coordinates taken November 15 and the vector connecting those 2 points in red:

[Note, stone 3 appears visually over stone 2 in the above rightmost frame.  That is because Google earth is plotting the cell phone generated coordinates which are, again, divergent by about 5 feet.  We would think the coordinates of the Great Tree will be similarly different between the cellphone coordinates and Google coordinates.  When the red vector is extrapolated out to Lower Manhattan, I do not believe there to be a substantial error; we will sense the meaning of the red vector.]

Where are we going with this?  Well, to what landmark in Lower Manhattan might the red vector in the above insert (right frame) be pointing?

So lets extend the vector, and to reduce the size of this post I'll show the origination of two hunches I had in a green vector and a red vector:

The red vector will end at one of four Lower Manhattan landmarks I'd guessed:  

No, the green vector that ends at the southern point of the North Pool of WTC and intersects the 9/11 audio memorial office (120 Liberty Street, WD Gann's early offices) DOES NOT intersect the Great Tree.  The green vector connects to WD Gann's gravestone #3, but does not intersect the "Great Tree."

The end point of the red vector is at a point I'd guessed based upon the movie that gave me the insight into the WD Gann's Map of Time; "Knowing."  The movie's next to the last disaster occurred in the subway station at Lafayette and Worth.  And what might be so important at that intersection other than a subway (the importance was not pointed out in the move)?

The tallest Federal building in the United States at 41 stories.  It houses operations of Homeland Security, FBI, Citizens and Immigration Services, SSA....the personnel that administer Federal law and services for one of if not the greatest city in the world.  A major target.

It would seem Mr. Gann might be pointing out the location of the next event in the life of New York City.  Or perhaps not.  [Correction 12/4/2015, please see HERE.]

[I am very disappointed in the lack of correlation between Google Earth coordinates and my iPhone 6 coordinates. My understanding is cell phone uses satellite and cell tower triangulation depending on whether satellite is available while Google is fully satellite.  Still, the results, whether cell tower triangulation or satellite determination appear somewhat systematic and reasonably accurate.  I have provided everything I have in this post in terms of GPS and the reader has access to Google Earth for free; all of the above can be replicated.  I doubt anyone will.]

[A nuance.  In the movie, an accidental train derailment occurs at the Lafayette and Worth subway station; in fact there isn't a subway station I could find in 'street view' of Google.  Indeed, there isn't an active subway station in or close to that intersection so an accidental train derailment cannot occur.  We are left with the vague impression that the red vector indicates, 'something will happen here' without further coloring save for the huge Federal Government presence.]

Jim Ross