172 



PROCEEDINGS OF THE AMERICAN \< U'l.MY. 



divided by LOO, and if the core were made up of 10,000 Blender 61a- 



mt'iits, the flux would sensibly disappear during the first thousandth of 

 a second. It is easy to get similar results for any other value of fi. 



TABLE VI. 



If the cross-section of the core were a circle of radius a, and if. after 

 a uniform magnetic field of strength // had been established in the 

 core the exciting circuit were suddenly broken, the intensity of the 

 field at any time, at any point distant r centimeters from the axis 

 would be given by the expression 15 



jf = 2 J[o.^ Sofa -r) 



h 



erfy 





where /3 J = p>i 2 /4~n and the whole flux through the core would be 



Ilnlr or I ^// > (63) 



In these equations n k i is the Hh root in order of magnitude of the 

 Bessel's Equation 



J (na) — 0. (64) 



15 Heaviside, Electrical Papers, 1, xxviii. Peirce, These Proceedings, 41, U»06. 

 Byerly, Treatise on Fourier's Series, etc., p. 229. 



