Mr. Laming on the primary Forces of Electricity. 497 



lion. The induction of this experiment will be easily arrived 

 at if we bear in mind that compensation being a constant 

 function of the major electrical force is necessarily appreciable 

 by any measure of that force ; and that it may be set up by any 

 given accumulation of free electricity in two or more com- 

 pensators at the same time, in opposite, or any directions. 



Table E. 



Diameter of attracted disc, 4?'75 inches ; distance, '6 of an 

 inch. 



Comparative Comparative 



• Quantities. Forces. 



r 30 6 



Glass coated with thick paper X 43 12 



L 60 24 



Plus coating of tinfoil, the un- f 32 6 



insulated coating of thick X 46 12 



paper \_ Q^ 24 



r 60 6 



Both coatings of tinfoil < %^ 12 



L 121 24 



The results in the preceding table plainly show that the 

 quantity of electricity susceptible of accumulation in con- 

 ductors varies with the nature of its compensator. 



The doctrine of compensation thus explains with great 

 precision the accumulation of different quantities of free elec- 

 tricity on conducting surfaces of dissimilar figure, under an 

 equal force of major attraction, or, as it is with sufficient pro- 

 priety called, under an equal intensity; and it enables us to 

 understand, however greatly the quantities of electricity in 

 equal surfaces of different figures may vary, that when the at- 

 mosphere is the only compensator, the compensating envelope 

 opposite to all the parts will have an uniform thickness. 



29. Hence if a conductor of irregular figure be charged 

 with electricity and freely insulated in the atmosphere, and 

 an uninsulated solid be made gradually to approach the con- 

 ductor at all points of its surface in succession, it will begin 

 to assume the compensation at exactly the same distance in 

 all the cases; and therefore it is true that the distance at which 

 a charged conductor can attract bodies is the same at all parts 

 of its surface. 



30. But as the penetrating body can under no circumstances 

 wholly displace the air around a conductor, whatever be its 

 figure, it can never wholly assume the compensation ; and 

 consequendy the whole force of attraction of any electrified 



Phil. Mag, S. 3. Vol. 12. No. 77. June 1838. 2 T 



