On Intermittent Currents. 123 



Examples: — I. Find U n N, N being = 625. 



U 11 N=U n (25 + 6)=U 11 31 = 31-22 = 9. 



II. Find UuiH, when N= 31415926536. 

 U 111 N=U 111 (536 + 926 + 415 + 31) = U m 1908 = U m 909 



= 909-888=21. 



III. Find U im 2sr, when n= 1004008016. 



U mi N= U im (8016 + 400 + 10) = U im 8426 



= 8426-7777 = 649. 



IV. Find U mll N, when n= 3-1415926536. 

 U lmi N= U lim (3 + 14159 + 26536) = U 1U11 40698 



=40698-33333 = 7365. 



V. Find U lim N, when n= 3-141592654. 

 U nm N=U im i(31415 + 92654) = U lim 124069 



= U m n24070 = 24070 -22222 = 1848. 



74 Brecknock Koad, N., 

 December 1879. 



XVII. On Intermittent Currents and the Theory of the Induc- 

 tion-balance. By Oliver J. Lodge, D.Sc* 



1. PT^HE telephone, considered as a scientific instrument, 

 JL seems destined to play an important part as a detector 

 of minute currents of rapidly changing intensity ; and the 

 general theory of intermittent currents is being brought into 

 prominence by its use. 



The equations to which most attention has been hitherto 

 directed have been those relating to the steady flow of a cur- 

 rent after the initial inductive or inertia-like effects have sub- 

 sided ; and in arrangements such as the Wheatstone bridge, a 

 double key is commonly used, in order to allow the introduc- 

 tory stage to subside before any observation is taken. The 

 galvanometer is essentially an instrument for measuring steady 

 currents, or for giving the algebraically integrated expression 

 for the total quantity of electricity which has passed in the 



case of transient currents ; that is, \ idt, r being small com- 



pared with the period of swing of the galvanometer-needle. 



Again, the electrodynamometer has an important use as an 

 integrator of the current without paying attention to sign; 



* Communicated by the Physical Society, a portion having been read 

 at the Meeting on the 24th of January, 1880. 



