481 PHILOSOPHICAL TKANSACTIONS. [aNNO 1747-8. 



If the non-electric be brought still nearer, the attractive force will be so much 

 increased, as not only to affect the effluvia, when they are driven off from the 

 point of the electrified rod, but to be capable of drawing them off from a consi- 

 derable part of the rod beyond the point ; and that with a velocity, and in a 

 quantity, sufficient to occasion both the spark, and blow, as well as the noise that 

 is heard. 



' The same is the case, when the non-electric rod, or a finger, is held against 

 the side of that which is made electrical : at a greater distance a light will appear 

 as issuing from the non-electric, the particles attracted from a large surface of 

 the rod (and therefore not visible as coming from it) being made to converge to 

 a point, are rendered luminous, and if brought nearer there will issue sparks in 

 the same manner as when held to the end. 



The sparks are always produced in the space between the non-electric and the 

 rod, and often appear as issuing from the non-electric. This appearance is pro- 

 bably owing to those particles which, by their elasticity, are reflected back again 

 from the non-electric towards the rod, and which, by striking against those 

 coming from it, produce both the sparks and noise that is heard ; and as the 

 particles often appear in luminous rays at the point of the non-electric, it 

 thence happens, that the spark is often kindled so near to the non-electric, as to 

 appear as issuing from it. 



Several ingenious gentlemen, from this appearance of a light at the point of 

 the non-electric, have imagined there was a current of electrical effluvia continu- 

 ally issuing out of it, and which, setting in towards the electrified rod, was the 

 cause of the attraction of the electricity : and this conjecture of theirs will seem 

 to be greatly favoured by the following experiment. 



If some of the fibres of a down-feather be fastened to the end of a small skewer 

 or wire, and made electrical, they will strongly repel each other, and will expand 

 themselves on all sides to the greatest possible distance from each other ; but if a 

 non-electric person bring the point of a pair of compasses, or any other small- 

 pointed body near them, they will be repdled from it, and driven up together as 

 with a blast of wind ; and in the dark a light will be seen as issuing from the 

 point ; from whence it might be concluded, that the fibres are repelled by efflu- 

 via issuing out of the point of the non-electric. 



As the Abbe Nollet endeavours to account for the attraction of electricity on 

 this principle, Mr. E. offers some considerations which, notwithstanding these 

 appearances, have induced him to be of a different opinion ; and they are founded 

 on the following observations. 1 . That however replete any bodies may be with 

 the electric matter, none of these phenomena are ever produced, unless the ef- 

 fluvia are first excited in some particular body, and put in motion, either by 

 rubbing, or some such like operation. 2. That the effluvia are not to be equally 



