die refpeiSlive Secant (for fuch Latitude) to the Radius* 
For, As the Co-Sine, to the Radius; fo is the Radius, 
to the Secant (of the lame Arch or Angle;) as Fig, 4. 
s. R ::R. /. 
21. So that (by this means) the pofition of each Pa- 
rallel in the Ghart, fhould be at fuch diftance from the 
Equator, compared with io many EquifioSial Degrees 
or Minutes, (us are thofe of Latitude,) as are all the 
Secants (^taken at equal^diftances in the Arch) to fo 
many times the Radius. 
22. Which is equivalent (as Mvy^iVright there notes) 
to a Projedlion of the Spherical furface ( fuppofing the 
Ey at the Center) on the concave furface of a Cylinder 
ereded at right Angles to the Plain of the Equator. 
23. And thedivifion ofMeridians,reprefented by the fur- 
face of a Cylinder eredied (on the Arch of Latitude) at 
right Angles to the Plain of the Meridian (or a portion 
thereof.) The Altitude of fuch Projection (or portion 
of fuch Cylindrick furface) being, (at each point of 
fuch Circular bafe) equal to the lecant (of Latitude) 
anfwering to fuch point. As Fig. y. 
24. This Projection (or portion of the Cylindrick 
furface) if expanded into a Plain, will be the fame with 
a Plain Figure, who's bafe is equal to a Quadrantal 
Arch extended (or a portion thereof) on which (as or- 
dinates) are erecJted Perpendiculars equal to the Secants, 
anfwering to the refpccftive points ot the Arch fo ex- 
tended : The left of which (anfwering to the Equu 
noHial) is equal to the Radius; and the reft continu- 
ally increafing, till ("at the Pole) it be Infinite. As at 
Fig- 6. 
2y. So that, as L. (a Figure of Secants erected 
at right Angles on EL, the Arch of Latitude extend- 
ed,) to E\\Ly redangle on the fame bafe, who's 
altitude El^ is equal to the Radius;) fo is EL (an 
Arch of the Equator equal to that of Latitude,) to the 
di- 
