54 



REPORT ON 



where 



A = value of m ', determined from an observation of deflection with the deflecting 



-A 



magnet at the distance r from the suspended magnet. 



A' = value of -, determined from an observation of deflection with the deflecting 

 JL 



magnet at the distance ?' from the suspended magnet. 



The following table contains all the observed values of A and A', together with 

 the computation of the corresponding values of P. The values of A were obtained 

 from deflections at a distance of 2.0 feet: those of A' from deflections at a distance 

 of 2.5 feet. 



The indiscriminate mean of all the observations gives 



P= 0.0166 0.0088 



But Peirce's criterion for the rejection of doubtful observations throws out those 

 of December 13 and May 14. Accordingly, excluding them, and taking the mean 

 of all the others, there results 



P= 0.0155 0.0057 

 and that value I have adopted. Hence, for r = 2.0 feet, we have 



and for r = 2.5 feet 



Log. (l - J l) = 0.001 68 

 Log. (l - -?) = 0.00108 



