MAGNETIC OBSERVATIONS. 



Magnet C. 32. 



51 





















Value of 



Date. 



Circle Readings. 



Differences. 



Scale 



DirT's. 



I Scale 

















Readings. 





Division. 



Nov. 16, 1865 



4° 



s' 



i s" 









5° d -o 







Nov. 16, 1865 







1 1 



45 



3 



53 



3° 



150.0 



IOO d .O 



2 '-335 



Nov. 16, 1865 



4 



6 



45 









50.0 







Nov. 16, 1865 







1 1 



45 



3 



5b 





150.0 



100.0 



2-35° 



Nov. 16, 1865 



3 





45 









75-o 







Nov. 16, 1865 



1 



10 



IS 





5; 



3° 



125.0 



50.0 



2 -35° 



Nov. 16, 1865 



T, 



7 



45 









7S-o 







Nov. 16, 1865 



I 



10 



15 





5; 



3° 



125.0 



50.0 



2-35° 



Jan. 18, 1866 



s 



tf 



15 









50.0 







Jan. iS, 1S66 



I 



40 



3° 



3 



55 



45 



150.0 



1 00.0 



2-357 



Jan. iS, 1S66 



4 



37 













75-° 







Jan. 18, 1866 



2 



39 



3° 





bV 



3° 



125.0 



50.0 



2-35° 



Hence for the magnet C 32, we have 

 1 scale division = 2'. 349 ± o'.oo2o. 



Magnet S. 8. 



















Value of 



Date. 



Circl 



e Readings. 



Differences. 



Scale 



DirT's. 



1 Scale 















Readings. 





Division. 



Nov. 16, 1865 

 Nov. 16, 1865 



4° 



359 



9' 45" 

 26 30 



4° 



43' 



iS' 



5 o d .o 



150.0 



IOO d .O 



2 '-833 



Nov. 16, 1865 



4 



9 45 









50.0 







Nov. 16, 1865 



359 



26 30 



4 



43 



15 



150.0 



IOO. 



2.832 



Nov. 16, 1865 

 Nov. 16, 1865 



. 2 







58 45 

 37 



2 



21 



45 



75-° 

 125.0 



50.0 



2-835 



Nov. 16, 1865 

 Nov. 16, 1865 







59 

 37 3° 



2 



21 



3° 



75-° 

 125.0 



50.0 



2.830 



Jan. 18, 1866 



5 



36 30 









50.0 







Jan. 18, 1866 







52 15 



4 



44 



ib 



150.0 



100. 



2.842 



Jan. 18, 1866 



4 



2 S 3° 

 3 3° 









75.0 







Jan. 18, 1866 



2 



2 



22 







125.0 



50.0 



2.840 



Hence, for the magnet S 8, we have 

 1 scale division = 2'. 835 ± o'.ooi3. 



The Moment of Inertia, and its Temperature Coefficient, of the Magnet C 32, was 

 determined as follows : Let, 



K T = moment of inertia of the magnet, including its suspending stirrup and other 

 appendages, at the temperature t. 

 AK= change in the value of K corresponding to a change of temperature of 1° 



Fah. in the magnet. 

 K' r = moment of inertia of the inertia ring, at the temperature r. 

 d t = internal diameter of the inertia ring, expressed in feet, at the temperature r . 

 d e = external diameter of the inertia ring, expressed in feet, at the temperature r . 

 ? = coefficient of expansion for a change of temperature of 1° Fah. in the metal 

 composing the inertia ring. 

 W = weight of the inertia ring expressed in grains. 



