We iiere sec, that, after a distance of j^jtli of an iticli' Sfi-om 

 the pole has been attained, the prodnct of the weight and distance 

 is constant. The divergences in the immediate neighbourhood 

 of the pole belong to the class the discussion of which will be 

 resumed further on. A slight correction will cause them to vanish. 

 Hence ^\ e luwc arrived at the law, that the attractive force between 

 the magnet and sphere varies inversehj as the distance. 



26. I\I. Dub of Berlin has lately produced an elaborate memoir 

 on the attraction of electro-magnets*. Though he has operated 

 with masses of soft iron of very divergent sha])es, the above law 

 is found, on closer examination, to pronounce itself with more or 

 less distinctness thvoughout the whole of his ^^periments. I 

 will take the libei^ty of copying liis first table.,, / 



Attraction of submagnetst 6 inches long and 1", ~^', ^" and ^" 

 thick, by a magnet 12" long and 1" thick, and a strength of 

 current of 20°. ! 



Contact. Submag. V' thick. Submag. j". Submag. i". Submag. |". 

 iflt \)(in ^'-'Ji^JioibgnJ Ju f)(HJoi> ^iilbBtuu^ib 0(1 j l^iJ^no*) •y/r iftskiT/ 



hjii; i'Hijjfiuf (i^j^!ij')d iif>:il.ollK/i(f ]-j3h')q i-d^/T^'nq '111 yi^Arllib 



/'j^-HilH liiioiihrlih ^Ai iK h'ii'iir^b'- od ton Blldi-r -y/r ^loriJiflStdii' 



//f3l|»rit ■nmil'-.i^.ofHd i? tA .^-olgii sdf ot OrO^^o/lo^^nioiO-gSlnl 



5 .ffoiJf5'iQj^)jiTOo boos a 0j*f^9'rr 07od(^fgg«3-rq/') n(^3g«'to 



obeffi ,-:.<!•■// J!.tn9(t/i¥)q/o 'tog'.i-o h'M?:i(i h^Miiir" f n-.il // JyMn^uvi 

 joiJ5 rft YJi^'frQlS^ 9f!t oi um'Q'M'.r^in ,tji(9;^§ . K ^'1 [9'AP'hi 

 -ftil3&dJ noqjj ddiMaih 'to 'iorrofOfSSuJt 'juimO^l'9) ot v/uvQ'IIIitj 

 ?.iH(i^[u fo9j« x(^JlJ9boin9mn')q:0>X^l .1oria0-(ll)riJ "io tj/O^^iu 



.•nrl^o rh.-> 0) ^i^>^.qqo v\^.,y'^.^, nru.. ^l^o ^i^nvm^^-^ 



.B ,^n1>^^h.'rufi-ma.;J K ■\Qmit n\T 0:W|mi Io >'-^^^hi 



(-fi >8 fH')\ftm^k O'^(ibn>g'5,o'f QiOgaf; q I'O'Q^^ m b'inifiJnoo 



9 0-07 "' 0-055 0-04 _ vmiKul 



J , Tlie liunibers iii tlie first; column deiiote the distance between 

 the bar and the magnet, and the numbers in the columns opposite 

 express, in pounds, the attraction of the respective bars. The 

 distance was regulated by means of a screw, a quarter of a revo- 

 lution being denoted by the fraction ^. The numbers 1, 2, 3, 

 &c. express 1, 2, 3, &e. revolutions. One revolution corre- 

 sponded to qryth of an inch distance; the experiments therefore 

 , commenced when a distance of jl^^th df an inch separated tlie 

 ■"magnet from the .submagnet.. .,','.''' '' ' ' 



° '^ iUI<r..,iii .ill; .ir'lm!:|/ , i .il'dilv/ io 'll. 



seut volume of this Jourual. , _^^ < iiKri'L)^ > ,1 



t Tills tcviu is a])i)lic{l to the attracted masr? 61 soft iron, ae^'Noie at 

 ]). 195 'jt'tlic prc'cciliiig iSuinbi'i' of this Journal, 



