While  tabular  forms  for  data  and  calculations  are
found  further  on,  they  are  simply  those  used  by  the
writer  in  ordinary  work,  and  should,  of  course,  be  modi-
fied to  meet  varying  local  conditions  and  the  convenience
of  those  employing  them.
PRELIMINARY   CONSIDERATIONS.  3

In  the  valuation  of  mines  in  the  Company  stage,  it
is  held  that  two  essentially  different  features  must  be
clearly  set  out,  one  being  the  appraisal  of  the  blocked
ore  bodies  or  probably  profitable  portion  of  the  deposit,
the  other  being,  in  the  case  of  veins  or  tabular  deposits,
the  estimate  of  shoot  dimensions  in  economic  units,  the
latter  as  a  bearing  upon  shoot  extension  in  depth.  It
should  hardly  be  necessary  to  add  that  the  last  may  not
be  the  only  factors  in  such  calculation  ;  in  fact,  when  a
vein  cuts  different  types  of  country  rock,  or  neighbouring
veins  show,  say,  zinc  and  coincident  reduction  of  precious
metal  values,  these,  instead  of  the  shoot  dimension,  may
be  the  dominant  consideration.
While  the  present  work  deals  with  elements  only,  it
is  not  meant  for  beginners,  nor  those  to  whom  the
commoner  problems  of  mining  are  wholly  unknown.
