246 



Mr. W. K. Parker on the 



[Jan. 19, 



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 experi- 

 ment the potential of the two cells was found to be reduced 8 per cent., 

 and was therefore very nearly 200 lbs. instead of two cells Daniell's. 



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. 



02 



d ! 8 



10 

 *l-2 

 *l-4 

 *l-6 



seconds. 

 10 

 20 

 10 

 20 

 10 

 10 

 10 

 10 

 10 



19 



20 



19 





18 



19 



19 





45 



46 



46 





46 



46 







175 



170 



170 



165 



230 



228 



226 





310 



308 



311 





373 



380 



382 





460 



460 



467 



475 



!} 



n 



18 

 22 

 30 

 33 



18 



43 



159 

 210 



288 

 350 

 428 



1- 2 



2- 2 

 2-33 

 2-67 

 2-77 

 310 



Condenser of 311 microfarads. 



0-2 





32 



32 



32 







32 



1 



311 



0-4 





63 



64 



63£ 





63* 





>> 



0-8 





127 



127 







127 





n 



1-0 





159 



159 





>> 



159 







1-2 





188 



187 



189 



>> 



188 







1-4 





220 



220 



221 





220 





» 



1-6 





252 



254 



252 254 



>) 



253 





>> 



1-8 





284 



283 



284 





284 







2-0 





316 



317 



317 





317 







* These readings are uncertain, being obliged to guess how much current remained 

 after the image had swung out and back, its momentum lasting longer than with 

 smaller deflections ; the true reading would therefore be greater than those obseryed. 



January 19, 1871. 

 General Sir EDWARD SABINE, K.C.B., President, in the Chair. 

 Prof. Alfred Newton was admitted into the Society. 



The following communications were read : — 



I. " On the Structure and Development of the Skull of the Common 

 Frog (Rana temporaria) ." By W. Kitchen Parker, F.R.S. 

 Received October 10, 1870. 



(Abstract.) 



At the close of my last paper " On the Skull of the Common Fowl," I 

 spoke of bringing before the Royal Society another, treating of that of 



