290 Lieut. Maury on the Probable Relation between 



take place near the north pole, so that the disengaged mag- 

 netism distributed over the bar becomes south polar on that half 

 which is turned to the south pole, but north polar on the other 

 half that is turned to the north pole. A substance where this 

 takes place is diamagnetic, it places itself equatorial. 



" When the bar of a magnetic substance is so qualified that 

 the separating action of the molecules on each other must be 

 taken into consideration, then it can become so strong that 

 the molecules in the middle of the substance are more strongly 

 magnetic than towards the ends. If we observe once more 

 two such particles near two such particles near the external 

 south pole, the south pole of the nearest will tend to recede 

 by an intensity ^^ from this external south pole, but the more 

 distant will turn towards it a north pole of the intensity n\ 

 but in such a manner that ^'i \\- Outwardly the two will 

 act with the intensity n'^-^ — s^, but this is north polar, there- 

 fore of a contrary nature to the exciting south pole. The 

 contrary will take place near the pole, so that the disengaged 

 magnetism distributed over the bar becomes north polar on the 

 half that is turned to the south pole, but south polar on that 

 half which is turned torcards the north pole. A substance 

 where this takes place is magnetic, it places itself axial.''^* 



" Applying the former to the theory of Ampere, I was 

 startled because it has hitherto taught only that currents 

 which are parallel and directed in the same way attract, but 

 if they are parallel and not directed in the same manner 

 they are repulsive ; therefore, that a current moving in the 

 direction of the hand of a watch, in a spiral, produces a south 

 pole on the entrance point in the spiral, but a north pole on 

 the egression point. Hitherto, only such spirals have been 

 constructed in which the current in every winding shews an 

 equal intensity." 



" But I tried to arrange spirals of the following kind : — 

 one of them is in such a way constructed, that on two copper 

 wires are soldered to each of them, fifteen thin wires covered 

 over with silk. The first winding backwards over the copper 

 wire, i. e., the first convolution of the helices, beginning at 

 the end, and proceeding towards the centre, is with all the 



* Page 48. 



