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



were therefore unable to find an empiric formula fitted to repre- 

 sent the results of their experiments ; but, taking only the nunir 

 bers obtained by means of the magnetizing spiral, we shall see 

 from the following Table that they agree as well as possible with 

 our own empiric formula*. 



Table III. 



Number 

 of pas- 

 sages. 



First needle. 



Second needle. 



Third needle. 



Observed. 



Calculated. 



Observed. 



Calculated. 



Observed. 



Calculated. 



1 

 2 



3 

 4 

 5 

 6 



CO 



8-39 

 9-34 

 9-66 

 971 

 9-90 



1015 



8-39 

 9-34 

 966 

 9-82 

 991 



10-29 



707 

 8-17 

 8-84 

 8-73 

 915 



9-32 



7-07 

 817 

 8-54 



8-72 

 8-83 



'9-27 



8-88 

 976 

 1008 

 10-43 

 10-27 

 10-31 

 1103 



8-88 

 976 

 9-99 

 1024 

 1029 

 10-31 

 10-64 



The augmentation of the magnetic moment by repetition of 

 the passages is independent of the duration of the immersion, as 

 Hermann and Scholz had ascertained; it is essentially connected 

 with the intermission of the action of the current. It must, 

 then, be admitted, since the induced currents themselves are 

 without sensible effect, that the magnetic equilibrium which suc- 

 ceeds the action of the currents modifies the distribution of the 

 magnetism in such wise that a second application of the same 

 force, acting under the same conditions, may add to the total 

 residual magnetism f. 



(2) Three other processes may be employed to magnetize a 

 steel needle within a coil : — 



a. The needle is introduced, the current established, and the 

 needle withdrawn slowly (establishment). 



b. The needle is introduced slowly, the current passing ; the 

 current is interrupted, and the needle withdrawn (interruption). 



c. The needle is introduced ; the current is established, and 

 * The authors do not state what is the limit of the errors of experiment 



in their measuring-process ; but it is certain that they exceed the greatest 

 differences between the numbers in the column of the observations and in 

 that of the calculated numbers. 



With the exception of the three experiments contained in this Table, the 

 authors confine themselves to the observation of the magnetic moments 

 corresponding to 1,2, and co passages. The application of the empiric 

 formula gives the third number by means of the two first, with sufficient 

 approximation whenever the magnetization has been obtained by the spiral. 

 In the opposite case the calculated third number is notably less than the 

 number observed. They found that the degree of tempering, the length of 

 the needles, and the duration of the immersions are without influence on 

 the results. 



t The fact we are describing should be compared with the known fact 



