10 
On  the  Climate  of  the  British  Islands 
adapted,  by  its  temperature,  and  the  ease  with  which  it  is  worked, 
to  gardening  operations.  There  are  extensive  market-gardens  in 
the  parishes  of  Sandy  and  Gritford  (names  evidently  derived 
from  the  nature  of  the  soil),  in  Bedfordshire,  where  large  quan- 
tities of  vegetables  are  raised  for  London,  Cambridge,  &c. 
The  new  red-sandstone  has  a soil  readily  receiving  and  commu- 
nicating heat ; it  is  spread  over  the  vales  and  low  lands  of  England, 
and  wherever  it  appears  there  is  fertility  and  beauty  of  scenery. 
The  temperature  of  Cheshire  is  not  so  high  as  might  he  expected 
from  its  shelter,  situation,  and  red-sandstone  soil.  This  arises 
from  the  extensive  pastures,  and  from  the  wood  so  thickly  scat- 
tered over  its  surface.  If  the  soil  of  Cheshire  was  used  as 
arable  land,  and  less  timber  grown  in  the  hedgerows,  the  summer 
temperature  of  the  county  would  be  raised  equal  to  that  of  other 
arable  districts.  The  gravel  and  conglomerates  of  the  old  red- 
sandstone  constitute  a warm  soil,  and  even  its  clays,  when  well 
drained,  readily  receive  the  solar  heat,  and  will  therefore  pay  for 
this  kind  of  improvement  better  than  any  other  soil. 
The  soil  on  all  the  Plutonic  rocks  (with  the  exception  of  Ser- 
pentine) is  of  a friable,  warm  nature;  this  is  particularly  the 
case  where  hornblende  prevails  in  the  trap  rocks.  The  early 
potatoes  grown  near  Penzance,  and  which  go  into  the  London 
markets  in  May,  are  raised  from  this  soil. 
Where  granite  is  found,  at  100  or  200  feet  above  the  sea,  the 
soil  is  remarkably  early  and  prolific.  Near  the  Land’s-end  and 
the  Logan  rock  such  a soil  produces  from  40  to  50  bushels  of 
wheat,  and  60  bushels  of  barley  an  acre ; but  at  an  elevation  of 
800  feet  and  upwards,  granite  becomes  a very  unproductive  soil. 
The  increased  quantity  of  rain  which  falls  at  that  height  does 
not  readily  find  its  way  through  the  close  texture  and  fissures  of 
this  rock,  so  that  swamps  are  formed  in  the  flat  lands  and 
valleys,  and  even  the  hill  sides  are  generally  covered  with  peat : 
this  soil,  so  warm  on  low  situations,  becomes  wet  and  cold  on  the 
hills.  There  is  no  land  whose  powers  are  so  rapidly  impaired  by 
elevation,  or  which  produces  such  contrary  effects  on  the  tempe- 
rature of  the  air,  as  that  which  lies  on  the  granite. 
But  a large  portion  of  the  soil  of  these  islands,  particularly  in 
England,  is  of  a heavy,  cold  nature,  and  not  well  adapted  to  the 
reception  and  communication  of  heat:  this  is  the  character  of  the 
stiff  yellow  clay  of  the  coal-measures,  of  the  soil  of  the  Weald  of 
Kent,  and  of  the  lias  and  other  clays. 
28.  The  rocks  and  soils  of  which  the  elevated  districts  are  com- 
posed are,  from  their  structure,  unfortunately  favourable  to  the 
production  of  peat.  The  close  structure  of  the  granite,  and  its 
defective  drainage  in  wet  situations,  have  already  been  noticed. 
The  slate  districts  of  the  south  of  Scotland,  Cumberland,  Wales, 
and  Cornwall  have  a better  under-drainage,  but  the  soil  is  much 
