CONTENTS. v 



. PAGE 



Computation of the coefficients $(, 33, @, \ G, for each compass at each station, from the 



constants, J,, c , ?., *, /, # ^, >, and @ . 193 



X X X X X X 



Comparison of the coefficients thus computed with those found directly from the observations 



at each station . . . . . . . . . .196 



Resulting probable errors ......... 198 



Does the theory accurately represent the semi-circular deviation ? 199 



Tables showing the most important features of the deviations of each compass during the 



cruise . . . . . . . . . . . .199 



Hard and soft iron forces . . . . . . . . .201 



Magnetic moment of magnets used for measuring horizontal force on board ship . . 202 



Observations for absolute force at the Admiralty Standard Compass .... 205 



Observations for absolute force at the After Azimuth Compass .... 206 



Values of >. . . . . . . . . . . . 207 



Values of g, h, k, R and A-Zf, for the Admiralty Standard and After Azimuth Compasses . 207 

 Values of a, b, e, and d, for the Admiralty Standard and After Azimuth' Compasses . . 209 



General equations for the determination of the deviations of the Admiralty Standard Compass 210 

 General equations for the determination of the deviations of the After Azimuth Compass . 211 

 Variations of the hard iron force, during the cruise, at the Admiralty Standard and After 



Azimuth Compasses . . . . . . . . .211 



Computation of the coefficients A t , B v C v D,, E v for each compass, at places where the 



deviations were observed on less than thirty-two points ..... 211 



Recapitulation of results . . . . . . . . .219 



Final conclusions .... . . . 220 



