528 



PROFESSOR W. E. AYRTON, MR. T. MATHER AND MR. F. E. SMITH : 



Below is a sample series of readings taken in the second determination on .Jan. 2, 



1906: 



January 2, 1906. 

 (1) Observations for constancy of resting point and of sensitiveness: 



Constancy : 



99-5 100-8 5 T 

 99-5 100-8 ^ 

 99-4^, 



200-3,, 



1-6, 100-6 I 

 1-7 100-6 } 2 

 1-7 J 



The second set of observations 

 was made 10 minutes after 

 the first set. 



Sensitiveness : 



10 milligrammes 

 on left. 



100 -7 r , 107 ; 



100-8 107-2 ^ 208-0, 



100-8 6 



10 milligrammes 

 on right. 



90-5 102 -0 6 1 

 90-6, 102-0 > 192-6 

 101 9, J 



Sensitivenes8 = 0-77 division for 

 1 milligramme. 



Cell. Coil. Case. Barometer. 



C. C. C. centiins. 



Temperatures at commencement of observations . . . 16-71 16-70 14-0 74-5 



(2) Determination of current : 



>mmence 

 conclusion 



16-71 



16-78 



14 -L> 



Mean "a" reading = 200 9 \ difference 

 "b" = 200-6,/ = 0-2, 



Mean "a" reading = 199 -6, \differerice 

 "b" ' = 200-5 9 / =0-9 4 



Effective mass of 

 weights 



Balancing mass 



= 15 -3935,, -0-0000:, 



= 15 -3935 4 - 0-0120 



-0-0004 

 = 15-3811 4 



Effective mass of 

 weights 



15-7313, -0-0000, 



Sum of balancing masses - 

 Mean current = s/31- l6T2/ N/4 x 7 



Ilakncing mass = 15-7313 -0-0100 



-0-0012 

 = 15-7201,, 



= 31-1012 grammes. 

 49964* = 1-01821 2 in amperes. 



* Formula (12), p. r>10. 



