MAGNETIC O B S E 11 V A T 1 N S . 



181 



The observations made at stations where the deviations had been determined on 

 all of the thirty-two points were first discussed. For that purpose the values of 

 the coefficients A u Ji t , ( ',, U n E u for eacli compass, at each station, were computed 

 from the deviations on the true magnetic points by means of the equations given 

 oh pages 126 to 128. A specimen of the form employed in making these com- 

 putations is appended. It sufficiently explains itself. 



Admiralty Standard Compass. Computation ok Coefficients B, and C,, from Deviations 



observed on 32 Points, on the U. S. Iron Clad Monadnock. 



Bahia, December 30, 1865. 





I. 







II. 





III. 



IV. 



Half Sum 





V. 





VI. 

















Half Sum 



of Cols. 1 



Computation 



Con 



putation 















of 



and II, 





of B,. 





,( c,. 

















Quantities 

 in Cols. I 



(changing 



Sibils ni 

























True 



Obsen 



•ed 



True 



Obsen 



ed 



and II. 



Col. II.) 



d 





» 







Magnetic 



Deviation 



Magnetic 



Devi a 



ion 











V 



Products ol 



« 



Products of 



Direction of 



of 





Direction of 



of 





Unchanging 



Semi- 



a. 



Col. IV by 



— 



Col. n 



by 



Ship's Head. 



Compass. 



Ship's Head. 



Compass. 



Part of 



circular 



~ 



Multipliers. 





Multip 



Lers. 















Deviation. 



Deviation. 



VS. 





-= 







NORTH. 



+ -° 



40' 



SOUTH. 



+ i° 



40' 



4- 1° 40' 



0° 0' 







0° 0' 



1 



o° 







N. by E. 



+ 1 



20 



S. liv w. 



+ 1 



20 



4-2 20 



4- 1 



s, 



4-0 12 



S, 



-f-o 



59 



N. N. E. 



+ 3 



40 



s. s. w. 



+ " 



00 



4-2 20 



4- 1 20 



\ 



+ 31 



■\ 



4- > 



■4 



N. E. by N. 



+ 4 



3° 



S. W. by S. 



+ 



3° 



+ 2 30 



4-2 



s» 



+ ■ 7 



N 



+ 1 



40 



N. E. 



+ 4 



40 



S. W. 











4-2 20 



4-2 20 



s, 



+ I 39 



s < 



+ 1 



39 



N. E. by E. 



+ S 







S. W. by W. 



— 



40 



4-2 IO 



4- 2 50 



N 



4-2 21 



N 



+ • 



34 



E. N. E. 



+ 5 



30 



W. S. W. 



— 1 



10 



4-2 IO 



+ 3 20 



\ 



4- 3 5 



\ 



+ ■ 



'7 



E. by N. 



+ 5 



40 



W. by S. 



— 1 



5° 



+ 1 55 



+ 3 45 



s, 



+ 3 4i 



s, 



+ 



44 



EAST. 



+ S 



20 



WEST. 



2 







4- 1 40 



+ 3 40 



I 



+ 3 40 















E. by S. 



+ s 



10 



W. by N. 



— 2 



10 



+ > 30 



+ 3 4° 



s, 



+ 3 36 



— s. 



— 



43 



E. S. E. 



4-4 



40 



W. N. W. 



— 2 







4- 1 20 



+ 3 20 



«■ 



+ 3 5 



— s, 



— 1 



17 



S. E. by E. 



+ 4 



20 



N. W. by W. 



— 2 







4-1 10 



+ 3i° 



« 6 



+ 2 38 



-y, 



— 1 



40 



S. E. 



4- s 



20 



N. W. 



— 2 







4- 40 



4- 2 40 



s« 



+ 1 53 



- s < 



— 1 



53 



S. E. by S. 



+ 2 



40 



N. W. by N. 



— 1 



10 



4-0 45 



+ 1 55 



s, 



+ " 4 



-N 



— 1 



3° 



S. S. E. 



+ 2 



10 



N. N. W. 



— 



10 



4-1 



4- 1 10 



B. 



4-0 27 



- s r 



— 1 



5 



S. by E. 



+ 2 







N. by W. 



+ 



30 



+ 1 >5 



+ 45 



»i 



4-0 9 



-s, 



— 



44 

















Sum of 4- terms = 



= 4-29 8 



+ 



9 



7 

















Sum of — t 

 Divisor 



irms = 



= — 



8 T 



9 



4 





8 I 



+ 29 8 



4- 



.4-0 



3 





B,= 



+ 3 38-5 



0.4 



N. B.— Easterly deviations are to be entered in this table with the sign 4- ; Westerly deviations with the sign — . 



