64 



MOMENT OF INEETIA OF MAGNET A. 6T. 



Observations for torsion. 



Torsion circle. 



Scale readings. 



Mean. 



DifF. 



14° 

 164 

 344 



74 



248—304 



361—234 



11—428 



190-370 



276 

 297 

 220 

 280 



For torsion with ring use 



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 



gt 23°» 31'. 9 

 24 53.1 



26 

 27' 

 28 

 30 



14.3 

 35.5 

 56.9 

 18.0 



1™ 21«.2 

 21.2 

 21.2 

 21.4 

 21.1 



1 21.22 



Temp. 75°. 



1 vibration =4 '.061. 



Vibrations with ring. 



No. of vibrations. 



Time by chronometer 1285. 



20 vibrations. 





 20 



40 

 60 

 80 



gi- 50"' 17».0 

 52 43.3 

 55 09.7 

 57 35.5 

 60 01.1 



2°'26«.3 

 26.4 

 25.8 

 25.6 



2 26.02 



1 vibration=7'*.301. 



Recapittjla,tion of Restjlts. 



March 18, 1858. 1 vibration, without ring 



with 



March 19 



1858. 



without 



II 



with 

 Mean by combination 



4».073 

 4.073 



4.071 

 4.063 

 4.061 



7^294 

 7.301 



7,301 



T=4.069 

 at 74°.0 



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 (with appendages) K becomes for the 

 temp. 69° (and corrected for torsion) 



K=K, {rj^r_j^ = 2.220 and Ig K= 0.34631. 



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

 different temperatures becomes : 



For 62°, lgK= 0.34628 and lg7i'K=^ 1.34058 

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



