372 Dr. Lament on the most advantageous Form of Magnets. 



The mass is here, as well as in the following scries of expe- 

 riments, determined by means of the balance, not deduced from 

 the dimensions above given, which arc only approximate. 



The most disadvantageous forms arc the prism with square 

 section and the cylinder, in which the mass is collected as much 

 as possible about the axis of the figure, while, on the other hand, 

 the greater widening of the mass in the other forms apppears to 

 possess considerable advantage. 



2nd Series of Experiments. — Twelve equal laminae of iron 

 plate (fig. 5), length 43"'-2, breadth 5"'-3, thickness 0'"'4, were 

 so managed that first a single one, then two, three, &c. laid 

 together, or rather joined together, were brought into the above- 

 mentioned spiral. When the twelve lamina? were laid together, 

 they formed a prism of equal magnitude with C in the first series of 

 experiments, and had a weight of 94-8 grms. The results were, — 

 Magnetic moment. Proportion to the mass. 



1 lamina . 



. . 3-53 



353 



2 lamina? . , 



, . 4-11 



2-05 



3 „ . . 



, . 436 



1-45, 



4 „ . . 



. 4-65 



116 



5 „ . , 



, . 4-94 



0-99 



6 „ . . 



, . 515 



0-86 



7 „ . 



, . 5-39 



0-77 



8 „ . . 



, . 5-61 



0-70 



9 „ . , 



, . 5-83 



0-65 



10 u . , 



. . 6-05 



0-60 



11 » . ■ 



. . 6-27 



0-57 



12 „ . 



, . 6-44 



0-54 



Here is shown in a striking manner how disadvantageous it is 

 to increase the thickness. 



As a deduction from the results given above, 14*4 parallelo- 

 grams would, according to the weight, be equal to the prism C 

 (Series of Experiments 1), and the whole magnetism of the same 

 would have amounted to 6 - 874; but a double comparison gave 

 7'194 — without doubt a consequence of this, that the parallelo- 

 grams had been covered in the heating with tinder [Zunder]. 



3rd Series of Experiments. — Six parallelograms (fig. 6) of 

 45"'-6 length, 0"'-3 thickness, and breadths 2"'-3, 4"'-6, 6"'-8, 

 9"'-l, ll'"-4, 13"'-7, were cut out of an iron plate, and after 

 they had been carefully heated were brought into the above- 

 mentioned spiral j the result was as follows : — 





Magnet 



ic moment. 



Mass. 



Proporti 



on to the mass. 



A 



. 



269 



2-8 





0961 



B 



i 



4-05 



5-8 





0699 



C 



. 



5 04 



90 





05C0 



1) 





5-77 



11 7 





0-493 



E , 



. . . 



652 



14-3 





0-451 



F 



. 



7-12 



167 





0-425 



