THE 
LONDON,  EDINBURGH,    and   DUBLIN 
PHILOSOPHICAL     MAGAZINE 
AND 
JOURNAL    OF   SCIENCE. 
[FOURTH   SERIES.] 
MARCH  1872. 
XIX.   On  the  Constitution  of  Matter.     By  M.  B.  Pell,  B.A., 
Professor  of  Mathematics  in  the  University  of  Sydney,  late  Fel- 
loiv  of  St.  John's  College,  Cambridge*. 
IN  the  following  paper  an  attempt  is  made  to  account  for 
some  of  the  properties  of  matter  upon  mechanical  principles. 
I  assume  that  solid  bodies  consist  of  isolated  atoms,  whose  linear 
magnitudes  are  so  small  compared  with  the  distances  between 
them,  that  the  atoms  may  be  supposed  incapable  of  giving  or  of 
receiving  any  energy  except  that  of  translation — and  that  the 
mutual  action  between  two  atoms  is  some  function  of  their  dis- 
tance, and  acts  in  the  line  joining  their  centres  of  gravity. 
Some  writers,  whose  opinions  are  entitled  to  much  respect, 
have  expressed  an  entire  want  of  faith  in  the  theory  of  isolated 
atoms  acting  upon  one  another  at  a  distance;  and  some  even 
hold  that  such  a  state  of  things  is  inconceivable.  This  is  one  of 
those  half  metaphysical  questions  upon  which  perhaps  no  two 
men  would  be  found  to  be  exactly  agreed;  but  to  me  it  seems 
no  more  difficult  to  conceive  that  atoms  should  have  been  created 
with  the  property  of  acting  upon  one  another  at  a  distance,  than 
it  is  to  conceive  that  they  should  have  been  created,  or  have  in 
any  way  come  to  exist  or  to  have  any  properties  at  all.  It  may 
be  that  the  bodies  of  the  solar  system  do  not  act  upon  one  an- 
other directly;  but  they  appear  to  do  so,  and  we  are  content  to 
assume,  provisionally  at  all  events,  that  they  do  really  so  act. 
*  Communicated  by  the  Author.  From  the  Proceedings  of  the  Royal 
Society  of  New  South  Wales,  having  been  read  September  6,  1871. 
Phil.  Mag.  S.  4.  Vol.  43.  No.  285.  March  1872.  M 
