GO 



REPORT ON 



The values of the Vertical and Total Force have been computed from the horizontal 

 force and inclination by the formulae 



Z=Xtand 

 B — X sec 

 where 



X= horizontal component of the earth's magnetic force. 

 Z = vertical component of the earth's magnetic force. 

 R = total magnetic intensity. 

 6 = magnetic inclination. 



All values of force are expressed in English units; namely, in terms of grains, 

 feet, and seconds. If it is desired to have them in metric units, expressed in 

 terms of milligrams, millimeters, and seconds, they must be multiplied by 0.46108. 



The observations of magnetic declination, inclination, and force are given in 

 full at the end of this section, but for convenience of reference the following 

 abstract of them is inserted here. 













Inclination. 



L05. 



X 







X= 





Date 



Declination. 







Log. mX 



Temp. 



Hor. Force 













Needle A. 1. 



Needle A. 2. 











Philadelphia, Pa. 



Oct. 



24, 1 865 











9.22363 



0-4S934 



57-5 



4.148 



Gosport, Va. 



Oct. 



28, 1865 













0.51303 



73-o 



4.709 



Gosport, Va. 



Oct. 



30, 1865 



2° 



37 '.8 W. 



^69° 2l' 



+69° 54' 



9.16787 



0.51492 



58.7 



4-7I7 



St. Thomas, 



Nov. 



13, 1865 







+49 3 6 



+49 3 2 



9.01026 



0.66791 



85-5 



6.749 



St. Thomas, 



Nov. 



16, 1865 







39.6 E. 



+49 39 



+49 44 



9.01014 



0.66888 



87.7 



6.768 



Salute Islands, 



Nov. 



28, 1865 







3.8 W. 



+34 27 



+34 42 



9.00868 



0.66679 



90.0 



6.742 



Ceara, 



Dec. 



13, 1865 



8 



28.8 W. 



+21 26 



+21 20 



9.02178 



0.65112 



89.5 



6.507 



Pernambuco, 



Dec. 



23, 1865 



10 



59.6 W. 



+12 6 



+ 12 10 



9-03I9S 



0.64340 



87.2 



6.392 



Bahia, 



Dec. 



27, 1865 



7 



56.6 W. 



+ 4 31 



+ 4 17 



9-04305 



0.63005 



98.0 



6.213 



Rio Janeiro, 



Jan. 



6, 1866 







—11 48 



— 11 46 



9.06444 



0.61386 



74.2 



5.960 



Rio Janeiro, 



Jan. 



9, 1866 



2 



41.8 W. 









0.61205 



So. 5 



5-944 



Monte Video, 



Jan. 



18, 1866 



9 



16.6 E. 



—31 11 



-30 58 





0.61892 



87.2 



6.049 



Monte Video, 



Jan. 



18, 1866 









-31 8 



9.05476 



0.61822 



87.2 



6.039 



Monte Video, 



Jan. 



19, 1866 



9 



25.0 E. 









0.61754 



89-S 



6-033 



Sandy Point, 



Feb. 



7, 1866 



21 



52.0 E. 



—54 52 



—55 2 



9.05044 



0.62523 



69-5 



6.121 



Valparaiso, 



Marcl 



2, 1866 



iS 



54-3 E. 



—34 5° 



—35 7 



9-03474 



0.64188 



69.7 



6.367 



Valparaiso, 



Marcl 



19, 1866 



15 



36.6 E. 



—35 28 



- 35 28 



9-03599 



0.63637 



76.2 



6.300 



Valparaiso, 



Marcl 



29, 1866 



IS 



54.8 E. 



—35 34 



—35 27 





0.64126 



68.2 



6.364 



Valparaiso, 



Marcl 



29, 1866 











9.03607 



0.63782 



68.2 



6.314 



Valparaiso, 



April 



7, 1866 



is 



49.4 E. 



—35 26 



—35 23 



9-03837 



0.63885 



67.0 



6.330 



Valparaiso, 



April 



11, 1866 



IS 



57.6 E. 



—35 29 



—35 36 





0.63697 



74.0 



6.312 



Valparaiso, 



April 



11, 1866 











9.03720 



0.63725 



74.0 



6.317 



Valparaiso, 



April 



13, 1866 



is 



53-9 E. 



—35 40 



— 35 12 



9.03692 



0.63730 



65.7 



6.307 



Callao, 



April 



26, 1866 



10 



29.6 E. 



_ 6 28 



— 6 29 



8.99132 



p.68120 



79.2 



7.001 



Payta, 



May 



7, 1866 



8 



53-o E. 



+ S 9 



+ 4 47 



8.97055 



0.70285 



77.0 



7-359 



Panama Bay, 



May 



14, 1866 



s 



55-8 E. 



+32 5 



+31 47 



8.95196 



0.71700 



82.2 



7.614 



Acapulco, 



May 



30, 1866 



8 



20.8 E. 



+39 49 



+39 58 



8.94841 



0.72363 



84.7 



7.740 



Acapulco, 



May 



30, 1866 



8 



23.6 E. 















Magdalena Bay, 



June 



9, 1866 



10 



40.5 E. 



+48 41 



+48 22 





0. 69240 



65.0 



7.178 



Magdalena Bay, 



June 



9, 1866 













8.98098 



0.6921 1 



65.0 



7-'73 



San Diego Bay, 



June 



15, 1866 



IS 



9.4 E. 



+57 51 



+57 56 



9.03746 



0.63241 



71.0 



6.261 



San Francisco Bay, 



June 



26, 1866 



16 



25.5 E. 



+62 13 



+62 31 



9.08320 



0.58777 



63.0 



5-643 



Washington, D. C. 



Nov. 



1, 1866 



2 



44.2 W. 



+7i 5i 



+72 13 



9.19956 



0.46695 



66.2 



4.300 



Washington, D. C. 



May 



6, 1867 







+7i 55 



+72 5 











