650 
Climate  of  the  British  Islands 
fastest  in  wet  and  moist  weather,  and  hence  grows  fastest  during 
September  and  October,  in  proportion  to  their  temperature,  on 
account  of  the  greater  moisture  of  these  months. 
4th.  The  above  remarks  apply  to  the  cereals  as  well  as  the 
other  grasses  whilst  the  sap  is  in  a vigorous  and  rapidly  circu- 
latory state,  as  it  is  in  most  plants  before  they  begin  to  form  their 
seed. 
From  what  has  been  before  said  on  the  distribution  of  heat, 
moisture,  &c.  in  the  British  Islands,  it  is  evident  that  all  the 
conditions  of  the  atmosphere  favourable  to  the  growth  of  grass  are 
fulfilled  in  Ireland  and  the  western  parts  of  England,  also  gene- 
rally through  the  whole  of  Scotland,  and  that  elevated  places  too 
high  for  the  growth  of  corn  and  too  wild  to  produce  naturally 
any  valuable  produce  might  by  being  brought  into  cultivation  be 
made  to  produce  abundance  of  green  food  for  cattle,  and  the 
produce,  other  things  being  equal,  may  be  easily  calculated  ; for 
in  elevated  places  moisture  sufficient  for  the  growth  of  grass 
is  always  present,  so  that  by  applying  the  remarks  I have 
made  to  the  temperature  of  the  several  months  of  the  year,  any 
person  may  calculate  the  value  of  the  produce  of  laud  thus 
elevated,  as  compared  with  land  situated  on  the  level  of  the  sea. 
That  the  universal  experience  of  agriculturists  points  out  Ireland 
and  the  western  parts  of  Britain  as  best  suited  for  the  growth  of 
grass  is  so  well  known,  that  it  would  be  out  of  place  to  attempt 
anv  proof  of  the  fact. 
The  Effect  of  Climate  on  the  Cultivation  of  the  different 
kinds  of  Grain. — It  is  certain  that  wheat  is  an  exotic  plant,  and 
its  cultivation  artificial.  Thus  it  differs  from  the  natural  grasses, 
and  it  requires  in  the  British  Islands  more  care  in  its  cultivation 
than  it  does  in  places  more  naturally  fitted  for  its  culture.  Wheat 
requires  for  its  successful  cultivation  to  the  best  advantage  a 
temperature  of  54J  during  the  year,  and  for  two  months  during 
the  year  a temperature  of  68J.  This,  except  in  very  rare  years, 
is  never  fulfilled  in  the  British  Islands;  therefore  wheat  can 
never  be  cultivated  here  to  the  same  advantage  as  it  can  in  a 
warmer  climate.  A continental  climate  too  is  more  favourable 
to  the  cultivation  of  wheat  than  an  insular  one,  wheat  requiring 
a greater  summer  heat  for  the  perfection  of  its  seed  than  any 
other  of  the  cereal  grasses.  Wheat  will  not  begin  to  flower 
with  a less  temperature  than  57  ’,  and  the  less  moisture  in  the  air  and 
the  less  rain  falls  from  that  time  to  harvest  the  better  for  the  crop. 
Hence  the  wannest  and  driest  seasons  are  the  most  favourable 
to  the  yield  of  wheat.  This  obviously  indicates  the  places  most 
advantageous  for  its  growth  in  the  British  Islands,  the  south  and 
eastern  parts,  or  those  having  the  greatest  summer  heat;  and 
experience  has  fully  borne  out  this,  for  comparatively  small  quan- 
