36 Mr. W. Sturgeon on the Tkeoty of Magnetic Electricity. 



poles, and one, at least, of each description, — it will next be 

 necessary to take into consideration in what manner the two 

 systems of polar matter affect each other, and in what manner 

 the elementary polar lines of each system become deflected 

 out of their natural rectilinear course by their mutual attrac- 

 tion of each other. 



If fine steel or iron filings be gently scattered on a sheet of 

 card paper, under which is placed a bar magnet, they will im- 

 mediately become polarized by the influence of the magnetic 

 matter enveloping the bar; and if they be slightly agitated by 

 hitting the paper a few gentle taps with a pencil or other such 

 light body, they will become arranged in multitudes of ex- 

 ceedingly fine lines, some of which will be straight, and others 

 curved, as in fig. 0. Conspicuous lines, each with a dash 

 across one of its extremities, are drawn, to show their general 

 positions in each system. 



In this arrangement of the ferruginous particles we have 

 perhaps a pretty correct picture of a longitudinal section of 

 the distribution and arrangement of the intangible magnetic 

 matter enveloping the steel bar. Near to, and around the 

 extremities of the bar, the two systems of polar lines proceed 

 in their natural rectilinear direction ; but those polar lines of 

 each system which are more vicinal to the neutral point, or to 

 the neutral line eq, which crosses the centre of the bar, in con- 

 sequence of presenting poles of different characters outwards, 

 do, by their mutual attractions, aberrate from their natural 

 course, and bend or incline towards each other; forming curves 

 of different degrees of flexure, according to the powers of their 

 reciprocal forces, and their distances from each other. If the 

 steel bar be cylindrical, and uniformly magnetized on every 

 side, then, whatever longitudinal line of this magnet be turned 

 upwards, or towards the paper, a similar arrangement of polar 

 lines will be exhibited, demonstrating in the most satisfactory 

 manner that the virtual polarizing magnetic matter completely 

 envelops the ferruginous cylinder. Fig. 1. and 2. represent 

 the distribution of fine particles of iron when strewed on paper 

 above the ends of the cylindrical magnet. 



Fig. 4. is a representation of the arrangement of fine par- 

 ticles ot iron, strewed on paper above a horse-shoe magnet, 

 which affords a tolerably exact idea of the direction of the 

 invisible polar magnetic lines as they are distributed in the 

 plane of the magnet. Fig. 5. represents the arrangement and 

 distribution of iron filings, scattered over a transverse section, 

 or over the poles of the same magnet. 



In fig. 4. it is observable that the magnetic polar lines exhibit 

 the greatest degree of aberration from their natural rectilinear 



