Unifilae Magnetometer. 



XXV 



wooden beam : the deflecting bar when removed and replaced, was carried with a thick 

 cloth glove or silk handkerchief, to prevent variation of temperature in handling. 

 In reversing the magnet, the same side was always kept next the bifilar magnet.* 



Table 2. — Determination of the Induction Coefficient for the large Deflecting Bar. 



27. The adopted value oi ~ = 0-0112. 



This value is very large, more than twice as great as that obtained for small 

 4-inch bars, and is evidently not to be neglected in the rudest mode of observation 

 for the horizontal intensity. 



28. In consequence of the more accurate determination of the value of K, the mo- 

 ment of inertia of the deflecting bar, and of k the bifilar coefficient, and on account of 



* It wiR in general be preferable to place the deflecting bar to tbe east or west (as in the present 

 observations), rather than to the north or south of the bifilar magnet, since I have found that the 

 centre of figure may differ considerably from the centre of magnetism ; perhaps, for the same reason, 

 when observations are made only on one side of the bifilar magnet, the deflecting bar should be in- 

 verted when it is reversed, since the magnetic axis may be nearer one side of the bar than the other. 



MAG. AND MET. OBS. 1844, Q 



