152 
Mr. Hellins on the Rectification 
+ — 
e ^yy + i = 7 1 '°^33520, 4 - “A — 0*0070593, 
— 7^3 B = o-ooooooi, — d = 6*7989144, 
sum of the posit, terms 71*0633521 ; the sum — 68059737; 
neg. term, & correc. — 6*8059737 ; 
the difference is 64*2573784 = the length of the first 
arch. 
When y = 20, we have 
A = H. L. = - 0*0499794, 
B = ~ — 0*0000415; 
of which two terms the first only is sufficient to give the re- 
sult true to eight places of figures. We now have 
. + — 
eVyy ~ f 1 = 141 5980226, + £ A = 0*0035341, 
0*0000000, — d — 6*7989144, 
sum of the posit, terms 141*5980226 ; the sum — 6*8024485; 
neg. term & correc. <— 6*8024485 ; 
the difference is 1347955741 = the length of the se- 
cond arch. 
When y is = 30, the value of A = H. L. is — - 
0*0333274; and since the value of B (as appeared in the pre- 
ceding operation,) need not be computed, we have 
+ 
e </yy -J- 1 = 212 2498528, — A = 0*0023566, 
neg. term and correc. — 6*8012710, — d~ 6*7989144; 
length of the third arch 205*4485818. 
sum 6*801,2710; 
