196 Prof. E. Bouty's Studies on Magnetism. 



the same diameter do not meet the axis of x at exactly the same 

 point, but in points nearer to the origin in proportion as the 

 degree of magnetization of the mother needle is less. Besides, 

 the curves themselves are not proportional reductions of the same 

 curve ; and if we take the ratio of the magnetic moment of a 

 rupture-needle to the corresponding saturated needle, this ratio 

 approaches towards unity in proportion as the length of the 

 needle diminishes. Therefore, if needles be taken from the middle 

 of a non-saturated needle, but which is regular and from 1 to 2 

 millims. in diameter, the shorter they are the nearer are they to 

 saturation. 



The difference which we have noticed in this respect between 

 very thin and thicker needles is important for the theory of mag- 

 netism. 



It remains to examine the condition of the end fragments of 

 non-saturated needles. I have limited myself to comparing the 

 magnetic moment of these fragments with that of equal frag- 

 ments from the middle of the needle. I ascertained that the 

 moment of the end fragments is below that of the middle ones, 

 and as much more so 



(1) As the primitive needle is shorter, 



(2) As the magnetization is less intense, 



(3) As the absolute length of the fragments is less. 

 The following are some examples : — 



millim. 

 f Length .... 131 

 Mother needle < Diameter ... 2 

 I Moment .... 127*3 



Divided first into three, then into six equal fragments. 



Eatio of the end third parts to the middle ones 803 

 „ „ sixth parts „ „ 0646 



millim. 



Mother needle /^"S* ••••141 

 ^Diameter ... 2 



Divided into five, then into ten and into twenty equal 



fragments. 

 Ratio of the end fifths to the middle ones . . 0*751 

 „ „ tenths „ „ . . 0*544 



„ „ twentieths „ . . 0*321 



In the same experiment, the ratio of the twentieths occupying 

 the second place from the ends, to the middle twentieths, was 

 found to be 0*785. 



