270 THILOSOPHICAL TRANSACTIONS. [ANNO 1/82. 



same, except the plate be brought so near the table as to occasion a transmission 

 of the electricity from the former to the latter ; at least the quantity of elec- 

 tricity will remain as much the same as the dampness of the air, &c. will permit. 

 The decrease therefore of intensity is owing to the increased capacity of the 

 plate, which now is not insulated solitary but conjugate. In proof of this pro- 

 position, if the plate be removed gradually farther and farther from the table, it 

 will be found, that the electrometer rises again to its former station, namely to 

 6o°, excepting the loss of that quantity of electricity, which during the experi- 

 ment must have been more or less imparted to the air, &c. 



The reason of this phenomenon is easily derived from the action of electric 

 atmospheres. The atmosphere of the metal plate, which for the present I shall 

 suppose to be electrified positively, acts on the table or other conductor to which 

 it is presented ; so that the electric fluid of the table, agreeably to the known 

 laws, retiring to the remoter parts of it, becomes more rare in those parts which 

 are exposed to the metal plate, and this rarefaction becomes greater the nearer 

 the electrified metal plate is brought to the table. If the metal plate is electri- 

 fied negatively, then the contrary effects must take place. In short, the parts 

 immersed into the sphere of action of the electrified metal plate, contract a con- 

 trary electricity, which accidental electricity, making in some manner a com- 

 pensation for the real electricity of the metal plate, diminishes its intensity, as 

 is shown by the depression of the electrometer. 



The 2 following experiments will throw more light on the reciprocal action of 

 the electric atmospheres. First, suppose 2 flat conductors, electrified both posi- 

 tively or both negatively, to be presented towards, and to be gradually brought 

 near, each other : it will appear, by 2 annexed electrometers, that the nearer 

 those 2 conductors come to each other, the more their intensities will increase ; 

 which shows, that either of the 2 conjugate conductors has a much less capacity 

 now, than when it was singly insulated, and out of the influence of the other. 

 This experiment explains the reason why an electrified conductor will show a 

 greater intensity when it comes to be contracted into a smaller bulk ; and also 

 why a long extended conductor will show a less intensity than a more compact 

 one, supposing their quantity of surface and of electricity to be the same ; be- 

 cause the homologous atmospheres of their parts interfere less with each other 

 in the former than in the latter case. Secondly, Let the preceding experiment 

 be repeated with this variation only, viz. that one of the flat conductors be elec- 

 trified positively, and the other negatively: the effects then will be just the re- 

 verse of the preceding, viz. the intensity of their electricities will be diminished, 

 because their capacities are increased the nearer the conductors come to each 

 other. 



This matter may be rendered still more clear by insulating the conducting 



