163 Prof. Tyndall on the Nature of the Force by which 



substance to assume one position ; and an attractive force, 

 which caused it to assume a different position : that, of these 

 two forces, the repulsive diminished more quickly than the 

 attractive, when the distance of the body from the poles was 

 augmented. Thus, the former, which was predominant close 

 to the poles, succumbed to the latter when a suitable distance 

 was attained, and hence arose the observed rotation. 



Towards the conclusion of the memoir published in the Sep- 

 tember Number of the Philosophical Magazine for 1851, 1 stated 

 that it was my intention further to examine this highly ingenious 

 theory. I shall now endeavour to fulfil the promise then made, 

 and to state, as briefly as I can, the real law which regulates 

 these complex phsenomena. 



The masses of soft iron sketched in fig. 1 were placed upon 

 the ends of the electro-magnet, with their pointsfacing each other; 

 between the points the body to be examined was suspended by 

 a fine fibre, which, passing round a groove, the substance could 

 be raised or lowered by turning a milled head. The body was 

 first suspended on the level of the points and its deportment 

 noted, it was then slowly elevated, and the change of position, 

 if any, was observed. It was finally permitted to sink below 

 the points and its deportment there noted also. 



The following is a statement of the results ; the words 

 * equatorial ' (E.) and ' axial ' (A.) imply that the longest hori- 

 zontal dimension of the substance examined took up the position 

 denoted by each of these words respectively. The manner in 

 which the bars were prepared is explained further on. 



Table II. 



