Researches in the Theory and Calculus of Operations. 289 



sion of its molecules coincides in direction with that of the 

 particles of the terrestrial meridian, and this rotative ten- 

 dency brings and retains the needle in line. 



Emanation proceeds in all directions from the centre of 

 a body. When this body is. cylindrical or parallelopidal, the 

 tension of the force increases toward each extremity, accu- 

 mulating from the centre on towards and becoming greatest 

 at the ends of the piece (Delarive); while the diverging 

 rays shorten as they approach, and reach a minimum at 

 the centre. Those diverging rays which reach the extreme 

 ends encounter the resisting action of the contiguous me- 

 dium : a reflection of force ensues in both senses, that is, 

 backwards into the cylinder, and outward into the medium. 

 In addition, there is yet emanative action perpendicular to 

 the axis of the cylinder throughout. As the medium has 

 the inferior density, the spherical and cylindrical emana- 

 tions overcome the medial at the surface, and prevail beyond. 

 From one extremity of the cylinder to the other, the cylin- 

 drical and rotative tensions of the atoms are respectively 

 equal ; while the spherical tensions decrease from both ex- 

 tremities to a minimum at the centre. A certain distance 

 from each extremity is found, where the emanative and 

 rotative forces all three compound to form a pair of new 

 centres or foci of force, a positive and a negative pole of 

 mutually reverse action, the many resulting effects of which 

 are well known. The entire magnet may be regarded as 

 made up of a fusion of elementary solenoids (Ampere), 

 and a helicoidal rotation of force in the atomic particles is 

 common to both. 



A simple way of transforming the atomic forces from 

 circular to spiral tension consists in applying the friction 

 of a ready made magnetic a few times, in the same direc- 

 tion, along the length of the bar to be operated on. Were 

 there no circular transmission of force in the pipe, this 

 rubbing in one direction would merely quicken the tension 



Trans, vii.'] 37 



