463 
that formula by Dr. Maskelyne into the following, adapted 
, r a x 1 1 + 8 x cof. 2 lat — ? cof. 4 lat. • , r 
to natural lines, — - 1 a is the excels 
3 ° 
of the radius of curvature at the pole above that at the equa- 
tor, and the fign of either term is only to be changed when 
the doubled or quadrupled latitude become greater than 90°, 
and lefs than 270°. 
I embrace this opportunity of mentioning another circum- 
ftance, wholly unknown to me at the time my Paper was com- 
pofed, From what has been there faid, at p. 216. and fo on to p. 
220. it will probably be inferred, that I confidered thepropofed 
mode of determining the differences of longitude by theobferva- 
tions of the pole ftar, made with a very accurate inftrument, 
rather as new, not knowing that the fame idea, or one nearly the 
fame, had before occurred to the Rev. Mr. Michell, and been 
treated on by him in his very ingenious Paper in the Philolo- 
phical Tranfaftions, Vol. LVI. for the year 1760. That I 
muff have read that valuable performance about the time of 
its publication is not to be doubted ; but in the lapfe of fo 
many years, every trace of it had gone from my remembrance, 
otherwife I would have mold certainly referred to it in the 
proper place, and with the attention that it fo well deferves. 
However, without entering here into particulars, it will obvioufly 
appear, that the one has not been borrowed from the other. 
ERRATA. 
In p. 195* 1 * 2 7 * for betvveen\Sravelines and Calais read between Wattcn and 
Graveiines. And in 1 . 28. for 56 42' o" read 46° 52' o". 
In p. 197. in the diftance of the parallel of Rodes from that of Dunkirk, for 
6* So' 51" 14'" read 6° 40' 51" 14'". 
In the laft line of the note at the bottom of p. 217. inftead of i° 40' 8". 8, 
read i° 49' 48". 8. 
in p. 221. line 6. from the top, inftead of T \ths, read T Vths. 
In the Table of Comparifon, p. 227. the lail line but one of the laft: column 
but one, for 44373.5 read 44372.0. In the next line below, for 38164.0, as for- 
merly corredted, read 38162.0. And in the right-hand column, laft line but 
one from the bottom, for 4 19. 1, read + 17.6. 
