As  far  as  practicable,  the  tests  used  in  the  experiments  described ­
  in  this  book  are  given  here,  together  with  the  instructions ­
  governing  their  use.  Mechanical  tests  and  other  non-paper
tests  can  be  represented  only  by  a  verbal  description.  Many  of
these  are  described  in  the  body  of  the  book  and  these  descriptions ­
  will  be  referred  to.
It  must  be  borne  in  mind  that  minor  improvements  in  the
character  and  use  of  these  tests  are  constantly  being  made.
Consequently,  in  compiling  this  Appendix  for  publication,  there
will  be  points  at  which  it  will  be  slightly  at  variance  with  the
procedure  described  in  the  body  of  the  book.
The  arrangement  of  this  material  is  based  on  manuals  actually ­
  used  in  giving  tests  to  incoming  applicants.  It  is  therefore
as  practical  as  constant  use  and  experience  have  been  able  to
make  it.  Tests  are  listed  in  numerical  order.  (No  classification ­
  of  tests  according  to  mental  faculties  is  given,  because  it
has  been  found  that  such  a  classification  has  little  practical
value,  besides  being  theoretically  unsound.)  Numbers  are
given  to  the  tests  in  order  to  do  away  with  the  clumsy  practice
of  recording  each  test  by  its  full  name.  Tests  are  therefore
usually  referred  to  by  number.
The  system  used  in  the  application  of  these  tests  is  the  unit
system.  That  is,  instead  of  printing  a  set  of  tests  in  a  single
folder  for  a  single  purpose—for  example,  a  clerical  series  or  an
inspectors’  series—each  test  has  been  preserved  as  a  unit.  Each
unit  can  then  be  combined  with  other  units  in  any  series  and
for  any  purpose.  This  method  has  been  found  necessary  from
an  economical  point  of  view  as  well  as  for  the  sake  of  greater
flexibility  and  accuracy  in  meeting  the  highly  specialized  demands ­
  of  employment.
393