Let (a, b, c) denote the centres of three atoms at rest^ and 

 {oL, /3, 7) the corresponding positions of the centres of these atoms 

 m motio)!, the cubes surrounding ;tl^§3fl cgpia'ep,being of unequal 

 dimensions in the latter case. 



Let a; — S.v, w, x + Sx be the ovdinates of a, b, c respectively; 

 let ?/ = F(a>) be the ordinate of /3, then ¥{x-hx), Y{x), Y{x + Zx) 

 will be the ordiuates of a, /S, 7 respectively. ' ! 



The pressures at «, /3, 7 are equal to the product of a constaiit 

 k, into the mass of the atom, divided.resp^ctively by the volujoeis 

 of matter constituting- each. atom. ; . . > w 



Pfofessor Pottfel* assiimes' the ;;^xessure ori the unit of tbe left 



face'cjf the cube ^ to feb — ^jaijdth^^.pre^Sixre'pli theuni^pf tli^ 



right face of the cube /3 to be „ 3 . This is equivalent to assu- 

 ming the unit pressure on the common face of two contiguous 

 atoms to be due to an attributed cube, whose side is the.scuusum 

 of the sides of the cubes> in contact. , , , ; i; ; , ; ,■ i i m 1 1/- /y. :nS\. 

 Adopting (for the moment) this hypothesis, we fin4 •! '^rumr^ 



,ir.ji.,-.fr. .^PyK.ai jjjijij ij.ii ..A, ',yii);if'ii^Jji-itPijiii//ulToi lI H^ j ^ 

 •io?.?.oio"i'£ '{d l)')8oqo-jq '{'jrioilJ -yft yiu fr^i to \{ii( laillomi -»- 

 B tmoi oJ rifidj Miim<^ 'Wij^Uy^Aih^^ 7^g;Vi doT orfl iii 'lalJo^I 

 898oqoiq doixlw ^inMiJ !M¥. i\ )((lji2 a|; I0 Aol-inuonib aJoIqxnoo 

 "to yjioob/ a'aolv/'j'/i lo -inlin i*>-)i-i'jiuj^in'3i')iiab 'jiU nislqza oJ 

 iji^^oJ ^yeoqo'iq /{ oidy^ ^'jooilJ a Uid ; ucm^usJJc 'io {rijtov/ gi buxio* 



to oite odt 10 m)[1i;T)\\r.i^ih >i[iiii-.v,fy-^Mii iitiiiei Juorfli// a'ull 

 -(noo '(d {(^ika^jl){jSy)i!a.^8x\(l^,^&L,S!ie\y'-^i'jb 0I a'iu?s:o-iq 

 .hoVu^n ffoiiooitfo aub jiym oJ Joji^zo J^toii ^ii/ian/;q/.o -lO noi8«;3'iq 

 ; naiioo »-w-i k ai /ikifib oJ 9-iij?;>!0-Kf 1(j^i*>rjiri odJ rsi O'gucib «irIT 

 birt itbc moving £&i:ie> auiiipig fooii /the 1 jlrfcss«f 0«) < pf ' 'ihe 1 dihibefe ' «*• 

 and 7 will ben i^iu-.il, ni; ,/ii")!,' ;i: ■: lit'ib 'jih .ii';!iii;iij/M :,. /;ul 



/ \ ,::: '.• ■ M i f ^ i ! I ■ ; I |i ' i nil (MJ^I'j!/ [ill! ijlli; .'|n j ; 1 1 1 O') li y ['))1 fjt 



At thi^ ^'yint pf hi?' Ijjyestigjaition , Professor Ppttev departs from 

 his previous hypothesis, vizi that a, ^, 7 are ol" different dimen- 

 sions, and tacitly assumes that the surfaces of the left and right 

 f^ces of the cube /3 are fully iiressed throughout the whole ,of 

 their extent by the cubes « and 7. ,, .h u 'i .>>-- loi'f 



Each of these surfaetes is assumed by him to be equal to 

 ■ ill'1'1') .((1 ,■!((, !ii^ tM(1 f.i;:-!^^ di, ' iimiin'io') ndt 



. • ' _(«/3 + /37)=^S.v. , 



l)-_inoiil-<i;t-bli) jil I _ii IT'.. \'.^.-,i -■' i/^*-' .. iinin '(iil 1 ^iiinn , a hf>i-) 

 By substituting this value hi the expression just given,' it is/9ftgjj i 



to'flnd tlic dodficieiif ^^ fdi-'tiie ^m-eniiM'equiitte' ■^'""'*' 



A ,',..|..i ,7 'il lii; ^Mfl ■■|nll!- I"" ■'■■I '('"^ 



JJut as the faces,, 9|,yth,fl, ^V»l^p,^<?^p„fl»ljr be pressed by the 



