  EGRET gamma-ray archival data used with GALPROP software show two ringlike
structures in Milky Way Plane which roughly tally with distribution of stars
([1] & references therein). To understand fully the implications of this and
similar results on detailed structure and rotation curve of especially Milky
Way Disk as well as rotation curves of other galaxies as derived from spatially
resolved spectroscopic data-cubes, a re-examination of the basis of the
connection between mass density and rotation curve is warranted. Kenneth F.
Nicholson's approach [2], which uses only Newtonian dynamics & gravity, is
presented.
