I call V P N P the elliptical halo, becaufe it ap- 
peared fo to me j yet, as the horizontal diameter was 
only guefled at, and nothing meafured, but the al- 
titudes of the points S, V, N, and T, which gave 
the diameter of the halo V N 45 0 , I will not be po- 
litive, that V P N P was not the circular one, and 
V X N Y elliptical, and 4 0 wider than the circle at 
X and Y, Which ever it was, it is, I think, worth 
preferving. 
