160 A. TAXAKADATE AND H. NAGAOKA. 



same maker, belonging to the Chemical Laboratory of the College. 

 The bra88 weights from Sartoriu« were a little heavier, and the old 

 weights a little lighter. The foll(3wing gives the results of the experi- 

 ments : — 



by Sartorius weights. by old weights. 



Observed 35.0561 grm. 35.0683 grm. 



Correction + .0038 -.0031 



Mass 35.0599 grm. 35.0599 grm. 



The mass of the maornet is thus 35.0599 o-rm. 



From these measurements of length, breadth, and mass the 

 moment of inertia of the magnet jibout an axis through its centre of 

 inertia, and perpendicular to its length, is found to be 144.98 at 0''C. 



The moment of inertia was calculated on the supposition that the 

 magnet is a parallelopiped having the dimensions given above. The 

 magnet, however, being distinctly curved, it was not sjitisfactory 

 to use the moment of inertia calculated in the above manner, and 

 it was therefore determined also experimentally. 



This was done in the usual way by comparing the times of 

 vibration, with and without an additional inertia. In order to eliminate 

 the diurnal variation of H, the vibrations were repeated several times in 

 which the inertia rod was alternately on and off. The inertia rod was 

 a solid C3dinder of brass belonging to a Kew magnetometer (64) 

 (length = 9.545 cm., diameter = 0.997 cm., mass = 63.071 grm.) 

 From the comparison of the times of vibration in these two cases, 

 the moment of inertia Avas found to be 144.995. The following table 

 gives the results of observations by Mr. Ota : — 



