ELl'X'TKOMOTIVE FOIU'KS IN TI[i: YOLTAK; CKLl,. 



47;j 



which is 

 d circnit 

 he Voltii 

 \ contact. 



probable 

 •imentally 

 X question 



say, pt'vliaps 

 Volta effect 



imatioii, anil 



f the contact. 



he intemlt'il 



wvnniT, li'^^ 



m\ tliey can 



in the ^^rciit 

 oU. (' Q»H-1K" 

 msclt' tiiuls it 

 at it is nnn't' 

 ton anil l'i'<'- 

 besiilcri those 

 as they have 



, in Paris in 

 ,vs the whole 



|,ir le (inx^^^ ';'' 



position very clearly, .and records a series of determinations of Volta forco 

 among nietals, determinations which are evidently tho most accurate and 

 satisfactory yet made, lie adopts the capital experimental method of 



so/ 



^■^^^ 



Ki, coiiiiH-ii^^itcur 

 (' ciii'scm'. 

 i: rheostat. 



I'Ki. C. Diiv^niiu of rdlat's ^k'tliud. 



I-KUKNUE. 



i m iiit('rni|>tiiir. 

 I r Icuille d'or. 



' A v.t a' iiliUcaux ntfr.xtifs do rt'loctroscopc. 

 1' pik's l);iiiicll i'uuriii^saiU \o. itmiMiit dii ; i'» l> liattuiies di' li)() volts cliacuno pour 



('iiiii|ifii>ati'iir. "■ ■■ rw-Kn charger le.-; platoau-x .V a'. 



ji' p plalcaiix dii condelisateiir (/< I'i.M', />' 

 mobile). 



Tlip (linsi'iiiii Vi'^. (1 jtretty well explains itself. The contact at m is hrokeii the instant liefore 

 J)' is raised. 



c 



- - -I V - - -1 



Fi(i. 



IVUiU's C'ondi'nser. 



I'ig. 7 .-hows Iiow this was done in practice. I'ullinir tlio string .\ raises a slidin;^ pin with ii 

 shoidder </ lixcd to it n niiilinietrc Ix'low the har it. 'I'lie pin thus lirst lircaks contact near 

 M. and then raises the iiin;j;ed liar it i;, to which the upper pl.ite .m is attached. The njiper 

 plate, licinir always in coiiTicclion with a liiltcry, reipiircs no special in-ulalion. 'I'he lower 

 l)latc is carefully supported liy a Thomson insulator i. The lower plate was consi'lerahly 

 smaller than the upper oni', and it was further protected from stray inductions hy a guard 

 screen. Screws c c served to rc,i;iilutc tlu' distance helween the plates. 



neutralising tho charge of a condenser by a PoggendorfT or compensation 

 method, and thus converts Kohlrausch's into a null method, for which a 

 very sensitive electroscope is all that is needed. The plates of tho two 



Louis le Grand, Xo. 401 : .Tnin 2L', 1 SSI . Sec also Journal dr Phyitiquc, 1 Sa 1 , xvi. p. OS, 

 iind Jlay ISSO. ' Ditlorenco do potent id des couches 61ectri(]uc.s qui rccoiiMont doux 

 mC'taux cu contact.' 



■-.If • 



m 



' -^ 111 



