64 



MOMENT OF INERTIA OF MAGNET A. 67. 



Observations for torsion. 



Torsion circle. 



Scale readings. 



74° 

 164 

 344 



74 



248—304 



361—234 



11—428 



190—370 



For torsion with ring use 



Mean. 



276 

 297 

 220 

 280 



21* 



77 

 60 



31' = 39* for 90° 

 42 



March 19, 1858. 



Vibrations without ring. (Mirror above.) 



No. of vibrations. 



Time by chronometer 1285. 



20 vibrations. 





 20 

 40 

 60 

 80 

 100 



9^ 23" 31^9 

 24 53.1 



26 

 27 



14.3 

 35.5 



28 56.9 

 30 18.0 



im 21S.2 



21.2 

 21.2 

 21.4 

 21.1 



1 21.22 



Temp. 75° 



1 vibration =4^061. 



Vibrations with ring. 



No. of vibrations. 



I by chronometer 1285. 





 20 

 40 

 60 

 80 



gi' 50° 



52 

 55 

 57 

 60 



l7^o 



43.3 

 09.7 

 35.5 

 01.1 



2"26^3 

 26.4 

 25.8 

 25.6 



2 26.02 



1 vibration=7\301. 



Recapitulation op Results. 



March 18, 1858. 1 vibration, without ring 

 " with " 



" without " 



1858. 



March 19 



with 

 Mean liy combination 



4 = .073 

 4.073 



4.071 

 4.063 

 4.061 



7^294 

 7.301 



7,301 



T=4.069 

 at 74°. 



T,=7.299 

 at 75°.0 



Temp. 71°. 8 

 " 71.0 

 " 75.0 

 " 75.0 

 " 76.0 

 76.0 

 " 75.0 

 " 75.0 



The moment of inertia of the magnet (witli appendages) K becomes for the 

 temp. 69° (ancf corrected for torsion) 



K=K, {fj^Y^ = 2.220 and Ig K= 0.34631. 



Using 0.0000068 for the coefficient of dilatation for 1° Fahr., tlie above Ig K for 

 different temperatures becomes : 



For 62°, lgK= 0.34628 and lgn-K= 1.34058 

 " 32, " 0.34609 " = 1.34039 (Chas. A. S.) 



