MAGNETIC OBSERVATIONS. 



55 



The Magnetic Moment of the Magnet C 32 was computed as follows : Observations 

 of deflection were always taken at two different distances, viz., at 2.0 feet and at 



2.5 feet. In general, the two values of -= thus obtained differed slightly from each 



X 



other, and the mean of the two was assumed to be correct. This mean was com- 

 bined with the value of mX, obtained from a set of vibrations observed on the same 

 day, and thus m was determined. In no case was more than one set of observa- 

 tions of deflections taken on any single day, but in a few instances several sets of 

 observations of vibrations were made. Under such circumstances, the mean of all 



the observed values of mX was combined with the mean of the two values of -=. , 



X 



and thus a single value of m was deduced. 



Let 

 m r = observed value of the magnetic moment at the temperature r. 

 m = value of m T after being multiplied by [ 1 -\- (t — 75°. 8) q ], or, in other words, 



after being reduced to the temperature 75°.8 Fab. 

 w = mean of all the observed values of in. 

 a = daily decrease in the value of log. m, expressed in units of the fifth decimal 



place. 

 d = time in days at which m is taken; d being counted from March 7th, 1866. 

 The following table contains all the observed values of log. m T , together with the 

 computation from them of the final values of the same quantity. The column 

 headed "days" gives the time in days counted from October 24th, 1865. 













Log. 







Concluded 



Concluded 



Date. 





T 



Log. m r 



[i+(-- 75°-%] 



Log. m 



Days. 



Log. tn 



Log. m r 



October 



24, 



[865 



57-5 



9.84148 



9.99S41 



9.83989 







9.83990 



9-84I49 



October 



3°, 



1865 



58-7 



9.84139 



9.99851 



9.83990 



6 



9-83979 



9.84128 



November 13, 



t86 5 



85-5 



9.83908 



0.00082 



9.83990 



20 



9-8395 1 



9-83869 



November 



16, 



[S65 



87.7 



9-8395I 



0.00104 



9-84055 



2 3 



9-83945 



9.83841 



November 28, 



1S65 



90.0 



9-83773 



0.00121 



9.83894 



35 



9-S3922 



9.83S01 



December 



r 3. 



865 



89-5 



9-S3645 



0.00117 



9.83762 



5o 



9- 8 3S93 



9.83776 



December 



2 3> 



rS6 S 



87.2 



9.83768 



0.00 1 00 



9.83868 



60 



9-83873 



9-83773 



December 



27, 



[865 



98. 



9-83655 



0.00191 



9.83846 



64 



9.83865 



9.83674 



January 



6, 



[866 



74.2 



9-839'5 



9.99986 



9.83901 



74 



9.83846 



9.83860 



January 



18, 



[866 



87.2 



9.^3666 



0.00100 



9-S3766 



86 



9.83823 



9-83723 



February 



7. 



[866 



6 9-5 



9-83783 



9-99945 



9.83728 



106 



9-83784 



9-83839 



March 



2, 



[866 



69.7 



9.83831 



9-99947 



9-83778 



129 



9- 8 3739 



9.83792 



March 



19, 



[866 



76.2 



9.83618 



0.00004 



9.83622 



146 



9.83706 



9-83702 



March 



2 9> 



[866 



6S.2 



9.83780 



9-99934 



9.83714 



156 



9.836S6 



9-83752 



April 



7, 



S66 



67.0 



9.83861 



9.99923 



9.83784 



165 



9.83669 



9.83746 



April 



11, 



[866 



74.0 



9.83716 



9-999S4 



9.83700 



169 



9.83661 



9.83677 



April 



*3> 



[866 



6S-7 



9-83711 



9.99912 



9.83623 



171 



9-83657 



9-83745 



April 



26, 



866 



79.2 



9.83626 



0.00030 



9.83656 



184 



9.83632 



9.83602 



May 



7. 



866 



77.0 



9.83670 



0.00009 



9.83679 



J 95 



9.83610 



9.83601 



May 



14, 



866 



82.2 



9.83448 



0.00056 



9-835 4 



202 



9- 8 3596 



9.83540 



May 



3°> 



866 



84. 7 



9.83602 



0.00078 



9.83680 



218 



9-83565 



9.83487 



June 



9. 



[866 



65.0 



9.83662 



9.99906 



9.83568 



228 



9- 83546 



9.83640 



June 



15. 



866 



71.0 



9-83493 



9.99958 



9-8345I 



234 



9-83534 



9.85576 



June 



26, 



866 



63.0 



9-8354S 



9.99889 



9-83437 



2 45 



9-835!3 



9.83624 



November 



1, 



866 



66.2 



9.83326 



9.99916 



9.83242 



373 



9.83263 



9-83347 





M 



eans 



75-8 







9.83729 



154 







