574  PEOFESSOE  PLUCKEE  ON  THE  iMAGNETIC  INDUCTION  OP  CETSTALS. 
the  greatest  and  mean  axis. 
We  get  as  near  as  possible 
73  31 
53~22-5 
= 1*38, 
this  number  indicating  the  relative  inducing  power.  We  may  regard,  therefore,  the 
four  numbers  22-5,  31,  53,  73  as  the  most  exact.  Among  all  possible  vertical  axes  of 
suspension,  the  minimum  number  of  oscillations  corresponds  to  a suspension  along  the 
greatest  axis,  the  maximum  number  to  a suspension  along  the  mean  axis.  Therefore  we 
are  authorized  to  prefer  22*5  and  31  to  23  and  31'5.  In  conformity  with  that,  we  may, 
according  to  our  theorem,  calculate  the  numbers  of  oscillations  in  the  thii'd  mode  of 
suspension,  which  admits  the  greatest  errors  of  observation.  The  two  resulting  numbers 
are  48-0  and  68-3,  instead  of  49  and  67.  Finally,  we  obtain  (34.), 
siniy= 
22-5  31 
53  ~73’ 
whence  &/=25°’8. 
63.  3rd.  We  shall  deduce  the  value  of  co  fi’om  the  observed  position  of  an  influenced 
Fig.  26. 
X 
crystal,  suspended  along  any  known  direction.  The  crystals  I had  obtained  exhibiting 
in  a very  pronounced  way  several  faces  of  the  primitive  octahedron,  Ave  suspended  one  of 
