MAGNETIC SÜEVF.Y OF JAPAN FOR THE EPOCH 189Ô.0. 9 



as observed b}^ the reflected line in the focus of the telescope 

 from its polished end, remained unchanged, when it was lifted 

 up slowly by screwing up the suspension fibre. 

 The instrumental constants are as follows : — 



fi = 3.S for all the magnets, fonnd hy magnetometric metliod. 



Those bar magnets were selected from ten of similar ones. 



The moment of inertia is calculated in two ways, once from 

 the linear dimensions and weight, and again by comparing it 

 with that of a brass cylinder belonging to Kew magnetometer 

 No. 64 hj vibration method : the latter gave always slightly 

 greater values than the former which may be due to heterogeneity 

 in its density; but as vibration method is not entirely free from 

 uncertainty, inasmuch as the time of vibration is usually 

 affected by small fluctuation in the value of the horizontal in- 

 tensity during the experiment, the mean of those two values is 

 adopted in reducing the observations. 



There are three dip circles belonging to the same committee 



