Re: New chart - dow/gold vs. gold/constitutional dollar

I don't understand this chart.  

To begin with, there are two y-axes, one going from zero to about 50, the
other going from 0% to 100%.  Does one axis pertain to one line and the
other the other?  If so, doesn't this mean these are two completely
separate graphs measuring to completely separate things?  Why is it
relevant to superimpose them?

I think I get it that the blue line is the Dow Jones Industrial Average, 
measured in gold ounces throughout the period.  In other words, on 3
September 1929, the Dow price was 18.44 ounces, and it is also close to
that now?

The gold line is what I really don't get.  This is gold valued in
"Constitutional Dollars"?  Since "Constitional Dollars" are valued at a
fixed amount of gold in the Constitution, why would this be anything other
than a straight horizontal line?  Apparently that isn't what the gold line
means, but what does it mean then?

Sorry for being so dense, and thanks for bearing with me on this one.