be the ninetieth degree of N ; k ^!n^ne ( be X'awn’ 
before the last mentioned parallel * , 
the segments should be so curved inwaico ^eir 
N ends, that each segment will constitute, from 
me equator or first parallel line upwards a com- 
ete quarter of an ellipsis,or quarter ot a diagram 
Sf a section of an oblong spheroid, cut through its 
, n Ver axis, considerably elongated, and rather 
° ridenlv bent inwards about the termination ot 
the se-ments, or quarter diagrams. These min- 
te adjustments may be dispensed with in pro- 
ractinV the figure, provided they are retained in 
th « mind or imagination.) That part ol the out- 
sale of this figure lying N. of the first drawn par- 
Jj.i or E. and W. line, will represent a sectional 
outline of th e sur face of the earth’s northern hem 
isphere from the-equator to the ninetieth degree, 
on either side of the polar opening. The parallel 
line last drawn will represent the true, or real ho¬ 
rizontal plain at the ninetieth degree; at which 
ninetieth degree the sun is in the horizon on Uiq 
21st of March and tnc 21st of September, annu¬ 
ally; hut, owing to known refraction, he must ap¬ 
pear there several days before the 21st of March 
and after the 21st of September. With your di¬ 
viders extended at any convenient distance, not 
1 less that one or two inches, set one foot where the 
upper or last drawn parallel line crosses the axis 
of the diagram, and describe a semicircle above, 
or N. of tiiis line, to represent the Heavens as ex¬ 
isting at the axis, or at the ninetieth degree. 1 
vide thin semicircle into 1 30 degrees, aim on the 
21st of June the sun will circulate around it, (ima¬ 
gining it a hemisphere of the Heavens,) --5 
above its base, on all sides, and perhaps apparent¬ 
ly some higher, inconsequonceof retraction. Now, 
from a point 23° SO 7 up either or both sic.es of 
this described semicircle, draw a right line, ow 
liquely from the centre of the sun suppose 0 
be there—through the point where the last drawn 
horizontal line crosses the axis, down as lai e- 
tween the two concentric circles, segments, 01 
spheres, as practicable ; proportion the diamet 
of the sun to the distance you lay him noun at 
from the earth, by describing a circle of a sm - 
PIe diameter around Ins supposed centre, (the 
