Mr. Laming on the primary Forces of Electricity. 491 



11. These principles explain the nature of electrical in- 

 duction, which they show to be a function of the electrical 

 force, whereby electricity separated from its natural connec- 

 tion obtains what may be called compensation by acting on its 

 equivalent of other common matter. Thus compensated and 

 their compensating bodies form with each other a temporary 

 or artificial state of equilibrium, perfect in direct proportion 

 as their compensation is perfect. 



12. We have supposed B, fig. 1. (7.) to be uninsulated; 

 but it is very obvious that were it either insulated, or itself an 

 insulating substance, the action of A upon it would be pre- 

 cisely the same ; only in the latter cases it would be rendered 

 similarly electrical, in consequence of the retention of plus 

 electricity virtually dismissed from connection with its com- 

 mon matter. 



13. Before we enter more fully on the subject of the distri- 

 bution of plus electricity on insulated conductors, we are led to 

 prove the existence of a new electrical force, by virtue of which 

 the electrical conditions of bodies become altered. The most 

 simple indication which we have of this force is observed in the 

 phaenomenon of the electrical spark, in which atoms of electri- 

 city are closely associated together by reason, as is commonly 

 taught, of the atmospheric pressure overcoming their repel- 

 lency, or, as I conceive, in consequence of their mutual attrac- 

 tion for one another. We may premise that the former of these 

 explanations is not consistent with facts ; for, let the atmo- 

 spheric pressure be given, then, the repellency being con- 

 stant, the density of equal masses of electricity should always 

 be the same, which is not true ; for a given quantity of elec- 

 tricity may be passed in an aggregated form between two con- 

 ductors through a certain thickness of rarified air, whereas 

 through a greater thickness it will pass only as a diflPused 

 stream. Again, I find that electricity passes as a dense and 

 brilliant spark in the most perfect vacuum that can be pro- 

 cured when the conducting wires are separated from each 

 other only by a plate of mica ; and in this case at least the 

 aggregation of the atoms must be ascribed to some other cause 

 than external pressure. 



14. While pursuing this inquiry, it occurred to me that the 

 nature of the force exerted by the electrical atoms for one 

 another might be best ascertained by observing the effect 

 produced by the mass of electricity in the earth on a certain 

 quantity accumulated in a conductor; and since the force 

 whose nature was sought was probably as great as the very 

 feeble force of gravitation, it seemed not unreasonable to ex- 



