﻿314 



Royal Society :— 

 Table II. 



Two platinum plates in acid and water, each exposing 1 square 

 inch surface. The resistance of R + R' = 100 Ohms in this Table; 

 by experiment the potential of the two cells was found to be reduced 

 8 per cent., and was therefore very nearly 200 lbs. instead of two 

 Daniell's cells. 



Approxi- 

 mate 

 potential, 

 in volts. 



Time of 

 electrifica- 

 tion. 



Throw of image by discharge 

 of plates. 



Current 

 remaining 



. after 

 discharge. 



Mean 

 minus the 

 current. 



Ratio of 

 capacity 



with 



different 



potentials. 



Value in 

 micro- 

 farads. 





seconds. 













0-2 



10 

 20 



19 20 19 

 18 19 19 



!} 



18 



1 



175 



0-4 



5> 



10 

 20 



45 46 46 



46 46 



:> 



43 



1-2 



210 



0-8 



10 



175 170 170 165 



li 



159 



2-2 • 



385 



1-0 



10 



230 228 226 



18 



210 



2-33 



408 



•i-2 



10 



310 308 311 



22 



288 



2-67 



467 



*l-4 



10 



373 380 382 



30 



350 



2-77 



484 



*l-6 



10 



460 460 467 475 



33 



428 



3-10 



542 



Condenser of 311 microfarads. 



0-2 





32 32 32 







32 



1 



311 



04 





63 64 63£ 



»> 



63i 



„ 



jj 



0-8 





127 127 



>> 



127 



5J 





> 



1-0 





159 159 



u 



159 









1-2 





188 187 189 



it 



188 



3} 





j 



1-4 





220 220 221 



>> 



220 



}> 







1-6 



... 



252 254 252 254 



5) 



253 



>> 





s 



1-8 





284 283 284 



JJ 



284 







i 



2-0. 



•• 



316 317 317 



>> 



317 



» 





> 



* The* 



,e readings 



>are uncertain, it being conjectural 



how much current r 



em a 



med 



after the 



image hac 



swung out and back, its momentu 



in lasting longer than with 



smaller c 



enections 



the true readings would therefore b 



3 greater than those o 



bserved. 



Jan. 19.— General Sir Edward Sabine, K.C.B., President, in the 



Chair. 



The following communications were read : — 



" Method of Measuring the Resistance of a Conductor or of a 

 Battery, or of a Telegraph-line influenced by unknown Earth-cur- 

 rents, from a single Deflection of a Galvanometer of unknown Re- 

 sistance." By Henry Mance, Superintendent Mekran Coast and 

 Persian Gulf Telegraph Department, Kurrachee. 



The resistance of each part of a circuit, such as that shown in 

 fig. 1, being known, the influence exercised by the shunt A B, as 

 well as the total resistance of the whole between x and y, can be 

 easily ascertained by simple and well-known formulse. 



But let a leakage r, which we will suppose gives perfect earth, be 

 applied at some point in the shunt A B, the deflection previously 



