Bedell and Crehore — Effect's of Self induction ^ etc. 389 



tions show a biaxial interference figure, the divergence of the 

 optical axes being large, about like muscovite. The cleavage 

 plate shows a decided pleochroism, for rays vibrating parallel 

 to c bright chrome green, and parallel to h yellowish green. 



Sp. gr. = 2-983. 



The analysis gave : 



Ignition 6*04 



Si0 2 46-73 



A1 2 3 29-00 



Cr a O, 2-73 



Fe 2 3 2-59 



MgO 3-03 



CuO -- -. 0-14 



Na 2 0'26 



K„0 9-25 



99-77 

 Chemical Laboratory, 111 S. 10th St. 

 Philadelphia, August 29th, 1892. 



Art. XLYII. — The Effects of Self-induction and Distributed 

 Static Capacity in a Conductor • by Frederick Bedell, 

 Ph.D., and Albert C. Crehore, Ph.D. 



The solution obtained by Sir Wm. Thomson for the varia- 

 tion of the current and the potential at different points in a 

 conductor possessing static capacity is given by Mascart and 

 Joubert, L'Electricite et Le Magnetisme, vol. i, § 233, and is 

 treated at length by Mr. T. H. Blakesley in his book on Alter- 

 nating Currents. The object of the present communication is 

 to give the solution for the case of a conductor possessing self- 

 induction as well as distributed capacity, and to note the effects 

 produced by the introduction of the self-induction. 



The rate of change of the charge on an element of the cable 

 is equal to the difference of the currents flowing into and out 

 from it ; and so, writing q for charge and i for current at any 

 time, and x for the distance of any point from the origin — 

 positive direction being that of current flow — we have 



dq _ di 

 dt dx 



If e is the potential of an element, its charge is q — Cedx, 

 where C denotes the capacity per unit length of the cable, and 

 the first equation may be written 



