Of GREATEST ATTRACTION. 227 



Let u zz fin z, then u — z cof z, and cof z x zz 1 — »**5 where - 



b n u 



fore, again, by fubflitution, /= a \f 1 + !L d — u *} ~~ 



u ♦ Let a' -f- b\ or AL a sr t\ then / = 



Z> » « £ « ?/ 



If, therefore, be fuch an arch, that — = fin 0, -^ = 



<5 // ,. b u 



c 



■ 

 bnu 



j.coff, and </i-£«' = cof ft then ^ _ ^ ^ = 



b? 



■ • r . 



" * c ° 3 = » ft Thus, /= « 9, and / ■= n <p + B, B being; a 

 col <p ° 



conflant quantity. 



Now, fmce fin <p = — = - fin z, <p is nothing when 2; is 



nothing ; and as / may be fuppofed to begin when z begins, we 

 have likewife B = o ; and, f=zn<p=zn multiplied into an arch, 

 the fine of which is to the fine of z, in the given ratio of c to 



b. Or / is fuch that = fin/= - X 5£ - ^ BC 



» f AG AL A AC 



Vol.VL— P.II. F'f Multiply 



