A D D E N 
D A 
At the end of page 386 add \ 
I11 fig. 4. draw a circle through the points N, m, t ; and at the maximum where 
tp j =pmX,np this circle will touch ca produced in t. From e the center of this 
circle draw ef perpendicular to nm, alfo the radii en and em ; and fn is the fine of 
nef, or half nEm, or of its equal mtn, to the radius en. But en = et ~ ff = 
pn4-pj!i . PN— — PM „ . , 
— , and fn = — — — . Therefore pn -J- pm is to pn — pm, or cd -f* cb is to 
2 2 
cd — cb, or ca -f~ cb is to ca — cb, as radius is to the fine of the greatefl angle of 
CA — 'CB 
deviation, which is therefore equal to — — ^ , radius being unity. 
E R R A T A to Vol. LXX. 
1 • 
Page 6, line antepenult, read be nearly mathematically. 
6 , l, penult, dele yet. 
7, /. 13, dele fe&ion abc, or 
7, l. 18 , at the end of the line add very nearly* 
.394, /. 13, tranfpofe general equation to the beginning of the line above* 
402, /. 6, 7, 8, for 9143 r, 9443. 
4 05, l. J, for the lajl , 1+-/ — 3 r, 1— — 3. 
405, /. 1 1, for the laft — — — - r. + ~ — K 
2 > 2 
443, end of the if line, for and x r, and X. 
548, /. io 9 for circumllances r, and which are. 
\ 
'*** There aae FIFTEEN Plates in this Volume. 
