1877.] 



Magnetic Observations at Kerguelen. 



land was not visible from the altazimuth hut (H), which stood, however, 

 not far from the magnetic pier (P), the two marks were connected as 



follows : — Let N, JN ' be the true north, and A, B, distant points on 

 a mountain seen over H from P. By careful readings of A, B, C, and 

 m from P and H the following values of the angle m were found — 7 18", 

 7' 26", 7' 20", 7'. 37", 7' 28", 7' 14", giving as a mean 7' 25". This, 

 applied to the azimuth of m from H (which was accurately known from 

 daily readings to be 55° 41' 12"), made the azimuth of m from P 

 = 55° 33' 47". The angle mPF was then found by repeated measures to 

 be 39° 44' 22", which gave as a final result the angle FPN =95° 18' 9". 

 As this is almost identical with the value obtained above from direct 

 solar observations, we can adopt the mean of the two, viz. 95° 18' 15", 

 as the azimuth of the Foreland; and thus we have only to take the 

 bearing of the magnet with respect to this point in order to obtain the 

 results included in the subjoined Table. 



Observed Declinations. 



W. De- 

 clination. 



Daily means. 



35 44 6 

 52 36 



35 44 6 

 52 36 



50 26 

 50 11 

 45 1 



50 26 

 50 11 

 45 1 



49 6 

 48 39 

 47 30 

 46 22 

 45 55 



48 8 



1874-75. 



Nov. 13 

 Nov. 24 



Dec. 3... 

 Dec. 10 

 Jan. 6... 



Jan. 13 



L.M.T. 



Circle 

 reading of 

 Magnet. 



h m 



3 50 p.m. 175 

 10 40 a.m. 

 10 50 



6 p.m. 



4 

 4 5 

 4 40 



12 



2 15 p.m. 

 315 



3 40 



4 15 



182 



236 

 1233 

 193 



43 55 

 34 20 



44"l5 



44 15 



45 5 



260 23 50 



Scale Circle 

 correc- reading of 

 tion. i Foreland 



Bearing 

 of mag- 

 net south 

 of Fore- 

 land. 



32 21 126 13 55 48 

 133 12 50 



187 19"35 

 184 20 20 

 144 16 



-31 54 

 •30 45 

 •29 37 

 •29 10 



210 58 50 



57 39 

 49 



51 19 



51 34 

 56 44 



52 39 



53 6 



54 15 



55 23 

 55 50 



H2 



