Am.  Jour.  Pbarm. 
Feb.,  1889. 
Photography. 
101 
times  obviate  tilting  the  camera,  etc.  The  bellows  should  be  extensible  to 
twice  the  focus  of  the  lens,  so  that  the  camera  may  be  also  used  for  copy- 
ing other  photographs,  etc. 
Three  double  backs  are  usually  provided  with  each  camera.  These  are 
light-tight,  and  the  first  operation  is  to  fill  them  with  the  dry  plates.  This, 
as  I  explained,  must  only  be  done  in  a  non-actinic  medium.  If  a  proper 
dark  room  cannot  be  fitted  up,  the  darkest  place  possible  should  be  secured, 
and  all  work,  such  as  development,  etc.,  always  reserved  till  night,  when  by 
the  aid  of  the  ruby  lamp  there  is  no  difficulty  whatever.  The  packet  of 
quarter  plates  is  then  opened  in  this  red  light,  and  carriers  are  provided  to 
enable  the  half  plate  dark  slide  to  be  used  for  any  smaller  plate;  so  the 
quarter  plate  having  been  placed  in  the  rabbet  of  the  ''carrier,"  film  side 
down,  and  secured,  the  camera  is  next  mounted  on  its  tripod  stand. 
Portraits  require  some  experience  in  "  lighting,"  posing,  etc.,  before  they 
can  be  taken  at  all  satisfactorily;  it  is  better  to  commence,  therefore,  with 
some  simple  object,  such  as  a  building.  Having  taken  up  some  coign  of 
vantage  uncap  the  lens,  and  with  the  cloth  drawn  over  your  head  to  keep 
out  extraneous  light,  proceed  to  focus.  Owing  to  the  rectilinear  propaga- 
tion of  light  the  image  of  the  object  of  course  appears  upon  the  screen  in 
an  inverted  position.  In  a  portrait  it  is  usual  to  focus  the  eyes  of  the  sitter 
only,  but  for  a  landscape  generally  the  foreground,  in  order  to  get  the  effect 
of  distance,  whilst  the  arrangement  of  the  picture  itself  will  call  into  requi- 
sition your  artistic  tastes  and  abilities. 
Having  thus  got  the  object  into  as  sharp  focus  as  possible,  by  means  of 
the  rack  and  pinion  adjustment,  recap  the  lens,  withdraw  the  screen,  and  in 
its  place  insert  the  dark  slide  containing  the  gelatin  dry  plate.  Now  comes 
the  most  important  operation,  that  is,  exposure.  No  hard  and  fast  rule  can 
be  given  for  this,  it  is  gained  only  by  experience  and  practice :  with  an  or- 
dinary dry  plate,  doublet  lens,  and  nicely  diffused  light,  two  to  three  sec- 
onds may  be  considered  the  average  time  to  give,  but  on  this  occasion  only 
draw  out  the  shutter  of  the  dark  slide  to  one-third  its  length  and  give  one 
second ;  then  draw  it  out  another  third,  being  careful  not  to  disturb  the  po- 
sition of  the  camera,  and  gi\e  another  second  ;  finalh7,  expose  for  one  sec- 
ond more  when  drawn  out  to  its  full  extent. 
There  will  thus  be,  on  that  one  plate,  the  results  of  three  exposures  of 
one,  two  and'three  seconds  each. 
The  next  step  is  the  development  of  the  photograph.  For  this  purpose 
many  different  solutions  have  been  suggested  and  used  from  time  to  time, 
but  the  one  I  always  use  recommends  itself  for  simplicity,  and  has  the  great 
advantage  of  working  well  with  almost  any  maker's  plate.  One  has,  more- 
over, considerable  control  over  it  during  development,  its  action  being  easi- 
ly modulated  to  suit  either  "  over  "  or  "  under  "  -exposed  plates. 
Jfc  Am.  bromid.  .  .  . 
Liq.  am.  fort.,  *880 
Aq.  ad  
Misce. 
5ss. 
.  3j. 
Sx. 
For  a  quarter  plate  take  1  ounce  of  the  above,  and  immediately  before 
