1822.] Magnetic Phenomena of the Electric Connecting Wire. 3 
sides is very great, or which comes to the same, that the poly- 
gon of a given diameter becomes a circle; or (2) that the 
length of the magnetic needle employed to examine the polarity 
of the endless magnet is very great compared with the length of 
a side of the polygon; then this elementary action of each side 
of the polygon cannot be observed; but the combined action of 
all the polarizations distributed on all the sides above the diame- 
ter parallel to the needle, will take place upon the magnet. By 
- this combined action, the needle shows an apparent arrangement 
of the polarizations in the endless magnet. This happens, pre- 
cisely in the same manner, in arranging a series of magnets in the 
manner represented by fig. 7. These magnets are disposed one 
after the other in such manner, that the heteronomous poles touch 
and follow each other alternately in the length a 6. In examin- 
ing the magnetic arrangement a 6, by means of a very small mag- 
netic needle, it will be observed that the elementary actions are 
represented in the figure by small needles. But in employing a 
magnetic needle which equals or exceeds the length of the line 
ab; this needle attracted by the combined action of all the 
polarities, and determined by the quality of the two extreme 
poles of this magnetic arrangement, will assume a constant 
direction. This arrangement indicated by the needle m n is only 
apparent, and we should deceive ourselves if we were to conclude 
from its position, that the arrangement @ 6 isa common magnet, 
presenting its poles at the two extremities, and the point of 
indifference in the middle. Let us suppose that the line a 6 is 
extremely short, it will then be impossible to examine the partial 
actions, and we must be content with observing the total or 
apparent action. 
_ 7. It is nevertheless easy to observe what happens in a poly- 
gonal endless magnet with respect to the arrangement of the 
needle around its periphery, if the length of the sides of the 
polygon are very small when compared with the length of 
the examining needle. In fig. 5, the needle m n is attracted by 
the poles NS NS = NS; the needle 0 p by the poles NS NS 
= NS; theneedle g7 bythe poles NS NS=NS. The needle, 
therefore, preserves its direction constantly the same, around the 
periphery of the polygon ; this would happen precisely the same 
upon all the points of a polygon of an infinite number of sides, 
or in the circle, as in fig. 6, so that there will be an appearance 
of the needle being directed by a current around the periphery 
in the same direction. 
8. A superposition, or continuation of endless magnets, con- 
stitutes the transverse magnet, i.e. in a transverse magnet every 
section perpendicular to its axis is anendless magnet. The trans- 
verse magnet presents no poles at its extremities ; but the hetero- 
nomous poles succeed each other alternately in the periphery of 
these sections. I have shown in a memoir which is inserted in 
the Annales de Physique already mentioned, that in forming a 
B2 
