472 ^ PHILOSOPHICAL TRANSACTIONS. [aNNO 1740. 



12. Excited electricity exerts itself in a sphere round the electric per se ; or 

 rather a cylinder, if the body be cylindrical. 



13. The electricity which a non-electric of great length, for example, a 

 hempen string 800 or gOO feet long, receives, runs from one end to the other 

 in a sphere of electrical effluvia. But all the supports of this string must be 

 electrics per se. 



14. If this string be branched out into many strings, the electricity will run 

 to all their ends. 



15. If the non-electric string, which is to receive and carry on tVie electric 

 effluvia, be not continuous, but has between its ends some electrics per se, the 

 effluvia will stop at the first of them, unless the interruption or discontinuation 

 of the non-electric be short ; because in that case the electricity jumps from 

 the end of the first non-electric to the beginning of the next, especially if the 

 air be very dry, even though the ends of the string should be about a foot dis- 

 tant, and no body but the air between. Sometimes indeed the distance must 

 not be above an inch or two. 



There are two sorts of electrics per se, known by what follows. A body im- 

 pregnated with electricity from one sort will repel all bodies that have that sort 

 of electricity, till they have lost their own electricity by coming to some non- 

 electric. But an electric per se of the other sort, though excited, will attract 

 all those bodies, though in a state of repulsion on account of the other elec- 

 tricity ; and so vice versa. 



Some Electrical Experiments made before the Royal Society, Jan. 12, J 740-1, 



By the same. N° 450, p. 637- 



It being a matter in dispute, whether there is any difference between the 

 electricity of glass, and that of gums and resins, Dr. D. made the following 

 experiments to settle that point. 



He fastened a string of dry cat-gut, which when dry is an electric per se, • 

 from one pillar to the other, at the end of the table in the meeting-room of the 

 Royal Society, about seven feet from the floor ; and to the middle of that cat- 

 gut fastened a silken thread about 1 feet long, which hung down, and at its 

 lower end had a down feather. Then rubbing the end of a stick of wax pretty 

 quick and strongly against his cloth waistcoat, the wax became electrical, and 

 attracted the feather, which stuck to it awhile, and then was repelled from it, 

 as long as it retained the electricity it had received from the wax : but having 

 touched the feather with his finger, it lost its electricity ; and, becoming a 

 non-electric, was again attracted by the wax, which gave it fresh electricity ; 

 and then it was repelled from it, and so toties quoties. When the feather was 



