2 
On  the  Climate  of  the  British  Islands 
3.  I propose  in  this  Essay  first  to  examine  and  determine  the 
leading  elements  of  climate , with  regard  to  the  British  Isles ; and 
then  to  apply  the  facts  so  established  to  agricultural  operations  and 
products. 
4.  The  atmosphere  is  the  vehicle  of  climate,  and  it  may  be 
considered  of  the  same  composition  in  all  parts  of  the  world, 
affected  only  by  the  substances  with  which  it  comes  in  contact ; 
thus  imparting  different  degrees  of  heat  and  moisture  to  particular 
regions.  Under  ordinary  circumstances  the  composition  of  1000 
parts  of  atmospheric  air  may  be  stated  as  follows  : — 
Oxygen 
Nitrogen 
Aqueous  Vapour 
Carbonic  Acid 
210 
775 
14-2 
•8 
1000 
5.  The  temperature  of  the  British  Islands,  and  the  distri- 
bution of  heat  through  the  year,  claim  our  first  attention.  The 
amount  of  heat  received  by  various  countries  is  generally  go- 
verned by  their  position  with  regard  to  the  sun  ; the  more  direct 
the  rays  of  heat  fall  on  the  ground,  and  the  less  of  our  vapoury 
atmosphere  they  pass  through,  the  greater  is  their  intensity 
and  effect ; but  our  own  geographical  position  appears  to  be  an 
anomaly  in  this  respect : we  lie  between  the  same  parallels  of 
latitude  as  the  ice-bound  coast  and  winter  stricken  soil  of 
Labrador,  yet  enjoy  on  our  south-west  shores  almost  a perpetual 
spring. 
6.  A correct  view  of  the  amount  and  distribution  of  heat  can 
only  be  obtained  from  long  and  repeated  observations  in  different 
places  : these  have  to  a considerable  extent  been  made;  but  they 
are  not  always  recorded  in  an  available  form,  and  are  scattered 
through  the  reports  and  transactions  of  various  societies.  I have 
availed  myself  of  such  reports  as  were  within  my  reach,  extracts 
from  others  have  been  kindly  forwarded  to  me  from  a distance; 
I have  tabulated  the  monthly  results,  and  extended  the  series 
through  a period  of  ten  years  when  it  could  be  obtained.  The 
valuable  tables  of  temperature  compiled  by  Professor  Dove,  and 
published  in  the  Report  of  the  British  Association  for  the 
Advancement  of  Science,  1847,  have  afforded  me  material 
assistance.  From  these  sources  I have  drawn  the  tables  of  tem- 
perature which  accompany  this  Essay,  rejecting  such  places  as 
were  superfluous,  and  endeavouring  so  to  arrange  the  whole,  that 
the  variation  of  temperature  for  any  month  in  the  year  may  be 
traced  from  south  to  north,  and  from  the  equable  climate  of  the 
Land's-end  on  the  west,  to  the  more  unequal  one  of  the  eastern 
coast.  (See  Table  I.) 
