Mifcettanea Cur to fa. 9 



A Letter from the Reverend 2V. 

 Wall is v Profeflbr 0/ Geometry in 

 the Univerfity of Oxford^rci Fel- 

 low of the Royal Society, London^ 

 to Mr. Richard Norris, concern- 

 ing the Collection of Secants ; and 

 the true ty 'tvi/ion of the Meridians 

 in the Sea- Chart, 



AN old enquiry, (about the Sum or Aggre- 

 gate of Secants) having been of late mo- 

 ved a-new ; I have thought fit to trace it from 

 its Original : with fuch folution as feems pro- 

 per to it : Beginning firft with the general 

 Preparation ; and then applying it to the Parti- 

 cular Cafe. 



General Preparation. 



1 . Beeaufe Curve lines are not fo eafily ma- 

 naged as Straight lines : the Ancients, when 

 they were to confider of Figures terminated 

 ( at leafl on one fide ) by a Curve line (Con- 

 vex or Concave) as -<4FXE, Fig. 1.2. Tab 1. did 

 oft make ufe of fome fuch expedient as this 

 following, (but diverfly varied as occafion re- 

 quir'd.) Namely, 



2. By Parallel Straight lines, as^fF, BG $ 

 CH r &£. (at equal or unequal diftances, as 

 there was occafion,) they parted it into fo ma- 



