200 



REPORT ON 



Compass and Station. 



Point. 



i 



Forward Alidade. 











Bahia ....... 



N. W. 



by 



N. 



— 3° 39' 



Sandy Point ...... 



N. W. 







— 4 34 



Forward Binnacle. 











Bahia ....... 



N. W. 







— 3 3 1 



San Francisco ...... 



S. W. 







+ 7 43 



Forward Ritchie. 











St. Thomas ...... 



N. W. 







— 4 55 



San Francisco ...... 



S. W. 



by 



S. 



+ 6 S3 



The following table shows, for each compass, the maximum change, A<5, in its 

 deviation, which occurred on any single point, together with the azimuth at which, 

 and the places between which that change occurred. 



Compass and Station. 



Azimuth. 



A} 



Admiralty Standard. 









Hampton Roads and Sandy Point 



S. 88° 52' E. 



7° 



53' 



After Binnacle. 









Hampton Roads and Acapulco . 



S. 82 43 E. 



4 



23 



After Ritchie. 









Hampton Roads and Panama . 



S. 84 27 E. 



7 



28 



After Azimuth. 









Hampton Roads and Sandy Point 



S. 48 31 E. 



1 



43 



Forward Alidade. 









Hampton Roads and Sandy Point 



N. 85 20 E. 



3 



39 



Forward Binnacle. 









Sandy Point and San Francisco 



N. 76 17 E. 



9 



42 



Forward Ritchie. 









Sandy Point and San Francisco 



N. 43 16 E. 



6 



18 



In order to show the difference between the values of the deviation computed 

 from observations made at a single station, and those computed from all the obser- 

 vations of the cruise, or, in other words, the difference between the theory and the 

 observations, let 8 be the deviation of a compass on any point, £, at a given station, 

 as computed from values of A x , B x , C 15 D ± , jf?„ derived from all the observations of 

 that compass made during the cruise; and also let 8' be the deviation of the same 

 compass, on the same point, at the same station, as computed from values of A u 

 Bi, C l5 D u E it derived from observations of that compass made on each of the 

 thirty-two points at the station in question. Then the following table shows, for 

 each compass, the maximum value attained by h — h' during the cruise, together 

 with the point on which, and the station at which, that maximum occurred. 



Compass. 



Station. 



Point. 



t— »' 



Admiralty Standard 



St. Thomas 



S. S. W. 



4- i° 41' 



After Binnacle 









Panama 



S. S. E. 



+ 1 14 



After Ritchie 









Sandy Point 



S. by E. 



— 2 51 



After Azimuth 









Callao 



S. E. by S. 



— 3 4 



Forward Alidade . 









Acapulco 



S. E. 



+ 1 36 



Forward Binnacle 









Valparaiso 



N. W. by W. 



— 1 41 



Forward Ritchie . 









San Francisco 



N. N. E. 



-f- 2 11 



