328 Mr. E. B. Rosa on the Determination ofv, the 



The wire was first in contact at m (fig. 3), and the re- 

 sistance a corresponding to joint capacity of condenser and 

 charging-system was 1930'0 ohms. The wire was now lifted 

 very slightly, and 194-0 ohms found to give no deflexion on 

 closing the key in the galvanometer-circuit. The wire was 

 then lowered to make contact, and the subsequent observations 

 in the order of the numbers made. Any leakage increases 

 the numbers alike in the first two columns, and if constant 

 does not affect the differences, which give the capacity of the 

 condenser. But the leakages are not constant, so that small 

 differences are thereby introduced ; this accounts in part for 

 the differences above, though of course small differences are 

 inevitable if there be no leakage. On June 6 the wooden 

 base of the condenser was thoroughly wet with a cloth ; and 

 the leakage thereby introduced changed the readings from 

 1924-0-186-0 to '1933 0-195-0, the difference, 1738-0, 

 remaining unaltered. 



The mean of the above differences is ... . 1735 '9 

 Correction: Excess at 20° C, 5*4; temp. corr., + 1*3 6*7 



1742-6 = a. 

 Box B = 100,120 at 23°'0 = d. 



E 5 (calculated as already explained), 2,435 7 800 = e. 

 Frequency of the fork, 130'075 = n. 

 1 B.A. unit= -98664 ohm. 



C = — i x r, onn . — tt^i C being the capacity of the con- 

 ned -98664 xlO 9 ' & f j 



denser in absolute electromagnetic units. 



log c = log 2,435,800 = 6-386642 



log d = log 100,120 = 5-000521 



log n = log 130-075 = 2-114194 



log -98664 xlO 9 = 8-994159 



22*495516 

 log a = log 1742-6 = 3-241198 



logC =20-745682 



logC'=log 50-069 = 1-699568 



log*? 2 =20-953886 



log v = 10-476943 



,-. v = 2-9988 x 10 10 cm, per sec. 



