40 Dr. A. Stoletow on the Magnetizing -Function of 



the other. Suppose, now, that the intensities of the two note9 

 are equal; then, according to Mr. Bosanquet's measure of 

 intensity, we shall have 



Q 2 



tr a, 



and 





<7 1 = 2 14 . a 



i. e. the amplitude of excursion of the lower note will be upwards 

 of sixteen thousand times as great as that of the higher — a con- 

 clusion which appears incredible. 



In reference to the principle on which the definition of 

 intensity must be determined, I may observe that we have no 

 direct consciousness of the amount of a velocity or force 

 impressed alike upon all parts of our frame; it is only when 

 the velocity or force produces relative displacement of different 

 parts of the system that we become conscious- of its existence, 

 and are enabled to measure its effects. The amount of dis- 

 placement of the nerves of the eye or ear is therefore neces- 

 sarily one element in the expression for the intensity of the 

 ray or note. The only other element remaining to be taken 

 into account is the time within which such displacement is 

 effected. Till the contrary is shown by indisputable experi- 

 mental evidence, I must contend that the simple ratio of one 

 of these elements to the other is the only measure of the inten- 

 sity of a light or sound which can be regarded as admissible. 



6 >~ew Square, Lincoln's Inn, 

 December 6, 1872. 



V. Gn the Magnetizing -Function of Soft Iron, especially with 

 weaker decomposing -p on: ers. By Dr. A. Stoletow, of the 

 University of Moscov: *. 



[With a Plate." 



IN Kirchhoff's generalizationf of Poisson's theory of the mag- 

 netization of soft iron, the knowledge of a certain empiric 

 function is of the greatest importance. This we will name the 

 magnetizing -function of iron, and denote it by k. 



In order to render palpable to ourselves the physical signifi- 

 cation of this quantity, we have to imagine an infinitely long and 

 thin iron cylinder in a homogeneous magnetic field \ the mag- 



* Translated from a separate copy, communicated by the Author, from 

 Poggendorff's Annalen. vol. cxlvi. pp. 439-463, having been laid before the 

 Moscow Mathematical Society on Nov. 20 (December 2), 1871. 



t Crelle's Journal, vol. xlviii. p. 3"0. 



