1 jft , // new Mtdod oj nuafur'wg thi EkSlru- Ci';iirge, 



IV. 



J Method of meafiiriiig the Fine of nn EUclrical Battoy during tht Tunc >f its being charged. 

 By Lieutenant Colonel HaLDASE '. 



I jVt rhe battery be infulated ; and at a fmall diRance from it place an uniiifulatcd elec- 

 trical jar -, alfo neir to the jar place one of Mr. Cuthbcrtfon's eleclromcters. 



The elearometcr being adjiiftcd according to the degree of force which is intended to be 

 employed as a mcafure of force to be communicated to the battery, conned the eleftro- 

 meter with the jar; make a metallic communication between the interior fide of the jir 

 and the exterior fide of the battery, and conned the interior fide of the battery with the 

 condudlor of an cleclrical machine. 



Then, by the operation of the eledrical machine, the battery receives a quantity of the 

 eledtrical fluid, and becomes charged. The fluid whicli departs from the exterior fide of 

 the battery, is received by the eleiirical jar, which alfo becomes charged ; but this jar, being 

 connected with the eleiarometer, explodes as foon as it acquires a force fullicieiit to put tlic 

 eleftvometer into motion. 



■ Kow, the quantity of the eleftrical fluid which is receri-ed by this jar, between each of 

 the cxplofions, is a meafure of the quantity of the fluid in die battery ; and the number of 

 explofions or difcbarges of this jar (hews the number of meafures which the battery conr 

 tains, and confequently the force which it is capable of exerting when difcharged. 



Demonflraiion. 

 THE eledrometer remaining under the fame adjuftment will require the fame force ta 

 put it in motion : this force refults from the quantity of eledrical fluid received by the jar ; 

 and fmce it is admitted, that, when effecls are the fame, the caufes of them muft be equal, 

 it is evident that the quantity of eledrlcal fluid contained in the jar at the time of 

 each explofion is the fame. 



It is alfo obvious, that the fum of all thefe equal quantities of the ele£lrical fluid which 

 was contained in the jar at the time of each explofion, is equal to the whole quantity con- 

 tained in the battery -, for, the battery being infulated, the jar received all the eiedrical fluid 

 which departed from the exterior fide of the battery ; and that quantity is faid (in the 

 theory of Dr. Franklin) to be equal to the quantity in the interior of the battery. 



Therefore it is manifeft that the number of explofions or difeharges of the eleclrical jar. 

 Is the number of equal meafures of the eledrical fluid which the battery contains. - 



But without putting too much confidence in any philofophical theories, the eficCls of 

 this operation may be more fatisfaaorily (hewn by the following experiments: 



Experiments. 

 A PIECE of iron wire, about 0.045 inches in diameter, and about two inches in length, 

 was placed in the circuit through wliich the difcharge of a fmall eleftrical battery,, which 

 contained about fix feet fuperficial of coated glafs, was to pafs. 



The eleftrical jar employed as the meafure of the charge of the battery contained 

 about 90 fquare inches ; and the adjuftment of the cledrometer was varied in each fet of 



• Conununicatcd ty tbc Author. 



experiments. 



