66 
Our  Canaries 
out  of  doors  or  in  an  adjoining  building,  so  as  to  avoid  having  any  fumes  from  the 
combustion  of  fuel  in  the  room  to  contaminate  the  air. 
The  latter  method  would  be  the  most  economical,  as  the  expenditure  of  fuel 
required  to  keep  the  pipes  heated  will  be  decidedly  less  if  the  furnace  and  boiler 
be  under  cover,  than  is  the  case  when  they  are  placed  in  the  open  air.  To  guard 
against  accidents  by  fire  the  boiler-bed  and  furnace  should  invariably  be  built  of 
bricks  and  mortar,  unless  one  of  the  portable  complete  apparatus  made  in  iron 
castings  as  supplied  by  horticultural  providers  is  used,  and  even  in  that  case  it 
will  economise  working  cost  to  construct  a  brickwork  shelter  for  it.  When  no 
other  available  building  adjoins  the  aviary,  and  in  the  case  of  the  span  roof  aviary 
standing  in  an  open  space,  this  shelter  should  be  built  against  one  end  of  the 
enclosed  space  outside  the  wire  flight,  as  shown  in  our  illustration  of  span-roof 
aviary. 
Where  a  gas  supply  can  be  connected  by  means  of  compo.  piping  a  portable 
hot-water  coil  can  be  obtained  which  is  very  effective  in  moderate  sized  aviaries, 
but  with  this,  as  with  the  more  commonly  used  and  extremely  risky  oil-heated 
apparatus,  there  is  a  perpetual  danger  of  something  going  wrong  and  wiping  out 
the  stock  in  a  few  hours  by  asphyxiation.  Any  system  which  has  its  source  of 
heat  in  the  room  must  have  a  protecting  cover  provided  with  a  flue  pipe  to  carry 
the  fumes  off  into  the  open  air,  and  the  outside  end  of  this  must  be  provided  with 
a  suitable  cap  to  prevent  a  down-draught. 
Do  not  forget  that  heat  may  give  rise  to  many  draughts  from  little 
unsuspected  chinks  and  crannies,  so  be  on  your  guard  to  discover  them,  more 
particularly  in  a  warm  room. 
LET   MALTHUS  FLOURISH! 
Having  got  through  all  these  preliminary  stages  of  Canary  culture  the 
population  of  the  aviary  will  present  itself.  The  accommodation  provided  by  any 
particular  aviary  will  depend  very  largely  upon  the  object  of  the  owner.  If  raising 
young  is  no  moment  then  a  rough  calculation  of  the  fioor  space  may  be  made  and 
taken  as  a  safe  index  of  the  capacity  of  the  enclosure  on  the  basis  of  one  bird  for 
each  square  foot  of  floor  space.    Cubical  capacity  is  of  little  value  as  a  guide ; 
Boiler 
A   SIMPLE  SYSTEM   OP   HOT   WATER  HEATING. 
