They  differ  from  ordinary  tenements  in  having
a  staircase,  or  staircases,  which  are  not  only
common  to  the  tenants,  but  open  to  the
public  ;  the  door,  if  any,  at  the  entrance  being
open  at  least  by  day.  Five  or  six  stories  is
the  usual  height  ;  the  buildings  commonly
stand  round  a  wide  square  or  quadrangle
entered  by  an  archway  from  the  street,   the


DWELLINGS,  INDUSTRIAL


663


entrance  to  the  staircases  being  from  within
the  square.  Light  and  air  are  primary  con-
siderations, and  tall  dwellings  should  not
stand  in  a  narrow  street,  but  with  an  open
space  round  them,  or  the  tenants  of  the  lower
rooms  will  have  insufficient  light.  The  stair-
cases are  sometimes  open  to  the  air,  but  if
built  within  the  block,  should  be  lined  with
glazed  bricks.  They  are  generally  so  tall  and
narrow  that  top  light  is  insufficient,  and  in
the  best  buildings  they  are  provided  with  good
windows.  All  windows  of  rooms  should  open
direct  into  the  space  in  front  or  back  of  the
buildings,  not  into  narrow  areas,  as  it  is  import-
ant to  get  direct  daylight.  Sanitary  accommo-
dation is  one  of  the  debated  problems  among
designers  of  these  buildings.  For  convenience,
cheapness,  and  simplicity,  it  is  better  to  collect
the  apparatus  into  a  distinct  portion  of  tlie
building.  Where  the  tenements  are  arranged
on  the  external  gallery  system,  with  only  one
or  tv/o  staircases  in  a  block,  the  w.c.  accommo-
dation is  sometimes  grouped  together  by  the
staircases.  But  among  the  more  respectable
class  of  residents  greater  privacy  is  preferred,
and  a  separate  w.c.  is  provided  for  a  small
group  of  tenants.  An  approved  arrangement
is  that  on  each  floor  of  a  staircase  there  should
be  four  sets  of  rooms,  one  wash-house  (with
copper  washing  trays  and  a  bath)  serving  the
whole  set  of  four,  and  two  sinks  and  closets.
