THE GANN WHEEL IS A SQUARE ROOT CALCULATOR

The Gann Wheel, what most people probably think of as the Square
of Nine, is sometimes called a "Square Root Calculator" or a
device that "Squares the Circle." This simple illustration may
explain how and why these terms came about. You probably
recognize that the illustration is just the first few rings of a
Gann Wheel with the numeral "1" at the center

In Square of Nine parlance we say things like 19 is 90 degrees
from 15. That makes sense only if you can visualize that this
rectangular table of numbers is enclosed in a circle (or series
of circles) of 360 degrees. In this case, the number 19 is 1/4
the way around the circle from the number 15, or 90 degrees in
circumference from 15. The number 34 is directly above the
number 15 and positioned one circumference or one ring outside
the circle that contains the number 15. In the same sense that
we can say that 19 is 90 degrees from 15, we can say that 34 is
360 degrees from 15, or one complete rotation of the circle from
15. That explains where squaring the circle comes from. A more
accurate expression would be that we're circling the square but
that never did catch on