220 MKAIOUIAI. OK JOHDI'll llllNltY. 



with a pluUi of zinc 12 inclica long and (i vvidti, iiikI HmrouuiUid'hy 

 (if)))|M;r, was tJiil).stiUi((!(l for the galvauio cleiaent iiHcd in tho fornici" 

 expurimciiUi; the weiglit lifted in this case Wiis 750 pounds."* In 

 illuHtration (if tlui f(!el>le jxjw*!!' (»f tins n»agn(ttie ]»ol<',s wlu-n (ixcrted 

 ti(!pariU,ely, it wan found tiiiit vvilh prccihcly th(t hiuii«! anangt.Mucnts 

 giving a holding power of YTjO pounds to the double eojitaet arma- 

 ture, (iidier ))olc, alon(i was cajjahle of Hnslaining only ft or 6 

 poun<ls; "and in this <!ase we never HiK^cccdcd in making it lift the 

 jirmature — weighing 7 pounds. We have n(!V<ti' seen the cireum- 

 stauee jioti(;e<l of so gritat a diderenee between a singh; poh; and 

 hi.th." 



JL'nri/H '^Quanfiti/" Af<if/nd compared v)ilh j1/o//'«.— About the 

 same time that Ibtnry was dcvt^loping this wondcuCul j)ow<'r in the 

 electro-magnet, Dr. (ierard JMoll, Professor of Nalural I'hilonojihy 

 in the Univcrsily of Iflrccht, was engagetl in a himilai- jcsearith. 

 in a ]>aper published in (he latter part of IH.'iO, he slates Ihat his 

 attention was drawn lo tin; electro magnet of (Sturgeon in 1H28, 

 during a visit to London. ( ''This aj)paratus 1 saw in IH2H at Mr. 

 Watkins's, curator of philosophical apparatus t(» the London 

 I lniv<'rsity ; and the hors(!-shoo with which Ih; piirfornuid the experi- 

 ment, became ca|)able all at once of supporting about nine pounds.;|; 

 I iimnediately det< rmined to try the vilU'i (tf a larger galvanic 

 apparatus on a Intnt iron cylindri<-al wire, and I obtainetl results 

 which app(!ar sistouishing, and are — as far ils the; intensity of mag- 

 netic force! in concei'ned, altctgcther new. 1 hav<i anxioimly looked 

 sinc(! that time into dilfcrent, Kciiutific continental and h!n|^di,sh Jour- 

 nals, without liuding any fuillier attempt to e\t<;nd and impiove 

 Mr. Sturgeon's original e.\p(triment." Moll's fu'st magnet,, a 

 hiU'se-shoe formetl of a round bar of iron about on(; inch thick, was 

 about eight and oiui-half inches in height, and had a wrapjutd (top- 

 per wire of about one-eighth inch diameter coihtd (iighty-threo 

 times around it. The weight of the horse-shoe antl wire was about 



♦ HIMIiiiuii'h Am. Journal oj ScU-nee, .luii. IHIll, vol. xlx, pj). 401, itih. 



\iltliliiilheijuii Unii'tiiHelio den /bitumen, olti. H»ii»l. 1H,'I(I, vol. xlv. in». ID Hf). AIho h'din- 

 huvyU Journal uj tiUunve, ()c!l, IHIIO. 



11 At llio (liilo iDfuri'iul to, Uonry had alitmity iixliUiUtuI iHiloro Uio AUMiiiy liihtl- 

 lutu, u luiic.li iiioi'ti jiowdi'Iiil niaijiiitl. I 



