Recently Paul Burke stated that he takes his measurements
of Dealey Plaza from the Robert Cutler map in Trask's
book Pictures of the Pain. The problem with that
methodolgy is that this map is highly inaccurate.
For example, the distance  on this map from the north
curb to the face of the TSBD is 280 feet. You can check
this yourself on the Cutler map by measuring the distances
with a mm ruler and then converting those measurements into
feet using the supplied scale. On Cutler's map the scale is 
40 feet which on my copy is 19 mm wide. The distance from
the north curb of Main Street to the face of the TSBD is
133 mm. Next, we solve for the ratio, as:
19:40::133:X where X=280
or 133/19 = 7. 7x40 = 280.
So, just how inaccurate is Cutler's map which Paul Burke
was using for his measurements? The original plans
for Dealey Plaza show the distance from the north curb of Main 
Street to the old building which later became known as
the TSBD was planned to be exactly 300 feet. The HSCA map
shows the distance from the north curb of Main Street
to the face of the TSBD is 300 feet. The original HSCA
survey plat of Dealey Plaza has a scale of 1 inch equal to
10 feet. My copy has a scale of 1 inch equal to 20 feet.
I use a Charrette 3820-20 triangular rule which has
markings of 10, 20, 30, 40, 50 and 60 to the inch, plus a 7X
loupe to measure to within a few inches of the real distances.
Contrary to what some people have said, my HSCA map is
not a blow-up I made from the HSCA published volumes.
If that were true, then how could I continually cite height
data from the map which is so faint that it does not show
up in the HSCA volumes or exhibits from the National
Archives, as I have done in several messages about
the relative heights of various objects in Dealey Plaza.
My copy is a standard 17x22 blueprint type of copy.
The HSCA map, as revised in 1981, is the most accurate
survey plat of Dealey Plaza available and is what all
serious researchers should be using. Using a map
which is inaccurate by 20 feet in 300 feet will produce
false results and is unacceptable for serious research.