INTRODUCTION". 65 



The division turned towards tlie west =: 79° 10' 

 = b. 



We have, therefore, 

 cotg. A = 0,9545 cotg. B =i 0,4355 



<:otg.a = 0,5269 cotg. b = 0,1914 



M = 1,4814 N = 0,6269 



ra = 0,4276 a = 0,2441 



m -f- 11 = 0,6717 



log. M = 0,17068 log, N = 9,79720 



log. n r= 9,S8757 log. m = 9,63104 



9,55825 19,42824 



log.{m + n) = 9,82718 log. (m + n) 9,82718 



log. = 9,73107 log. 9,60106 



Mura. 0,53836 num, 0,39908 



0,39908 + 



f 0,93744 



cotg. t = 2 ( 1 = 64° 53' 



^ 0,46872 



The arithmetical mean of the four observations 

 gives (33° m'.. 



Though this method so certainly attains the ob- 

 ject, yet the complete application of it at every 

 new determination of the dip, would be by no 

 means advisable, since the frequent reversing of 

 tlie poles would not only be troublesome to the 

 navigator, but, probably, detrimental to the needle. 

 It is better to use a needle which is so accurately 

 balanced, that its centre of gravity may coincide, 

 if not precisely, yet as nearly as possible, M'ith the 

 middle of the axis. This operation, therefore, is 

 properly the business of the artist, who, without it, 



VOL. I. F 



