( 447 ) 
tween EBC and EDC, though both are fubtended 
by the fame Line BD: for their Differences are 
the Angles BAD and B E D. Therefore this In- 
equality was likewiie to, be confidered ; and com- 
pounding both together, Tho . Godfrey pitched on the 
Ratio of 7 to ii, for the Radius of the Curve to the 
Radius of the Inftrument, which is - 6.3636 to 10. 
But on further Advifement he now concludes on 6A ; 
and a Curve of this Radius of an Inch on each Side 
of the Center to an Inftrument of 20 Inches Radius 
or of ftth of the Radius, whatever it be, will in no 
Cafe whatever, as he has himfelf carefully compti- 
ted it, produce an Error of above 57 Seconds? and 5 tis 
very well known that Navigators (as they very fafely 
may) in their Voyages intirely flight a Difference of 
one Minute in Latitude. 
This Radius is the true one for the circular Place 
to an Arch of 77 0 if, and the Variation from it is 
nearly as great at 90 Degrees as at any Arch below 
it, the greateft below being at about 44 Degrees, 
which is owing to the Differences expreffed by the 
laft Figure above, and not to thofe of the Curvatures 
or circular Places. Yet this Variation of 57 Seconds 
arifes only when the Spot or Coincidence falls at the 
Extremity of the horizontal Sight or Vane, or a 
whole Inch (in an Inftrument of 20 Inches Radius) 
from the Center, and then only in the Altitudes or 
Arches of about 44 or 90 Degrees. And in thefe, 
at the Diftance of half an Inch from the Center, the 
Variation is but i fo much, viz. about 14" ; and at 4 
of an Inch, not 4" ; at the Center tis precifely true. 
Therefore as an Obfervation may be taken with it in 
one fourth of the Time, that Davis's Quadrant, on 
