[shaw] THE KELVIN-VARLEY SLIDE POTENTIOMETER 



By substitution in equations (8) we obtain 



95 



* Ql 2 Q 



R ^ v i + [*(*- 2T») + t "£] = **.£+• 



*v p 



■*+5?i) 



4 Çj 2V Q + 



(10) 



*ioi = i ^ + [* (d 99 -d 98 + . . +2^) - 1- ^1 =* V-^-4- a 101 



j 

 where a u a 2 , a 3 , etc., can be calculated at once from b, k and d since we 



may substitute 5006 for — V ' -~r . As an aid to the numerical work 

 it is useful to note that 



a„ =kd„-2 — a n -i 



(ID 



Let us assume, temporarily, that 2 R n is equal to 101,000 ohms 



n 



exactly, where 2 R„ represents summation of the resistances from 1 



i 



to n inclusively. By addition of equations (10) we obtain 



(12) 



hence 



and 



(13) 



(14) 



101 



that is to say, the total correction for a reading n is 2 a n — 



101 



n 2 a„ 

 l 



101 



