Mr. W. Brown on Steel Magnets. 



275 



where r = distance in centims. of tbe centre of the magnet 

 from the centre of the magnetometer-needle, 

 I = half the distance in centims. between the poles of 

 the deflecting magnet, 

 H = *151, the horizontal component of the earth^s mag- 

 netic force, 

 ^ = the deflexion in degrees of the magnetometer- 

 needle, 

 W = the weight of the magnet in grammes. 

 The following Table (IV) gives the data and calculated 

 magnetic moments of the various magnets made from the three 

 different specimens of steel; and the accompanying curves 

 (fig. 2) show columns 2 and 4 of the table in a graphic 

 form, where the dimension ratio is taken as abscissa and the 

 magnetic moment per gramme as ordinate. 



Table IV. 



Specimen I. 



Length and 

 diameter of 



Dimension 



Weight of 



Magnetic 



magnet, in 



ratio, l/d. 



magnet 



moment 



centims. 





iu grammes. 



per gramme. 



20x3 



66-6 



iro 



69-9 



15 „ 



50-0 



8-25 



59-0 



10 „ 



33-3 



5-5 



57-0 



8 „ 



26-6 



4-4 



51-9 



6 „ 



200 



3-3 



44-8 



4 „ 



13-3 



2-2 



32-5 



2„ 



6-6 



11 



15-2 



1 „ 



3-3 



•55 



696 



Specimen II. 



20x265 



75-5 



8-6 



90^5 



15 „ 



56-7 



6-4 



83-7 



10 „ 



37-7 



4-3 



71-0 



8 „ 



30-2 



3-44 



64-6 



6 „ 



22-6 



2-58 



53-8 



4 „ 



15-1 



1-72 



41-2 



2 „ 



7-6 



■86 



12-4 



1 ,, 



3-8 



•43 



5-5 



Specimen III. 



20X-27 



741 



90 



78-4 



15 „ 



55-6 



6-75 



75-0 



10 „ 



370 



4-5 



700 



8 „ 



29-6 



3-6 



59-6 



6 „ 



22-2 



2-7 



45^4 



4 „ 



14-8 



1-8 



27-3 



2 „ 



74 



•9 



10-7 



1 „ 



3-7 



•45 



5^0 



T2 



