Results of experiment 'with globes 121 







which the coated jar was electrified, by which means the jar and conse- 

 quently the hemispheres were always electrified in the same degree. This 

 electrometer as well as the pith balls will be described in [Arts. 244 and 

 248] ; the strength of the electricity was the same as was commonly used 

 in the following experiments, and is described in [Arts. 263, 329, 359, 520]. 



225] My reason for using the glass jar was that without it it would 

 have been difficult either to have known to what degree the hemispheres 

 were electrified or to have kept the electricity of the same strength for a 

 second or two together, and if the wire had been suffered to have rested 

 on the hemispheres while the jar was charging, I was afraid that the 

 electricity might have spread itself gradually on the sticks of glass which 

 supported the globe and hemispheres, which might have made some error 

 in the experiment. 



226] From this manner of trying the experiment it appears: 



First, that at the time the hemispheres are electrified, there is a perfect 

 communication by metal between them and the inner globe, so that the 

 electricity has free liberty to enter the inner globe if it has any disposition 

 to do so, and moreover that this communication is not taken away till 

 after the wire by which the hemispheres are electrified is removed. 



Secondly, before the hemispheres begin to be separated from each 

 other, the wire which makes the communication between them and the 

 globe is taken away, so that there is no longer any communication between 

 them by any conducting substance. 



Thirdly, from the manner in which the operation is performed, it is 

 impossible for the hemispheres to touch the inner globe while they are 

 removing, or even to come within T %ths of an inch of it. 



And Fourthly, the whole time of performing the operation is so short, 

 that no sensible quantity of electricity can escape from the inner globe, 

 between the time of taking away the communication between that and 

 the hemispheres, and the approaching the pith balls to it, so that the 

 quantity of electricity in the globe when the pith balls are approached to 

 it cannot be sensibly different from what it is when it is inclosed within 

 the hemispheres and communicating with them. 



227] The result was, that though the experiment was repeated several 

 times*, I could never perceive the pith balls to separate or shew any 

 signs of electricity. 



228] That I might perceive a more minute degree of electricity in the 

 inner globe, I tried the experiment in a different manner, namely, before 

 the hemispheres were electrified, I electrified the pith balls positively, 

 making them separate about one inch. When the hemispheres were then 

 separated, and the tinfoil, x, brought in contact with the globe, and 

 [* Dec. 18-24, 1772, Arts. 512, 513, and April 4, 1773, Art. 562.] 



