028 
Climate  of  the  British  Islands 
during  different  seasons  about  3°  from  the  mean,  which  for  the 
whole  of  the  British  Islands  may  be  about  4 7°.  It  is  during 
this  month  that  a change  takes  place  in  the  relative  tempera- 
ture of  our  western  and  eastern  districts  ; for  whilst  from  Septem- 
ber to  April  the  western,  and  during  the  months  of  December  and 
January,  even  the  northern,  had  a higher  temperature  than  the 
south-eastern  parts,  from  April  to  September  the  eastern  and 
south-eastern  have  a much  higher  temperature;  the  maximum 
of  their  higher  temperature  as  compared  with  the  western  and 
northern  parts  occurring  in  July.  No  month  is  exposed  to 
equal  extremes  of  heat  or  cold  with  April  ; a change  of  wind  from 
the  south-west  to  north-east  will  frequently  cause  a difference  of  50° 
of  temperature  in  twenty-four  hours;  and  one  or  two  nights  will 
often  destroy  the  fairest  prospects  of  the  horticulturist,  and  scatter 
the  buds  and  blossoms  of  our  fruit-trees  after  we  had  fondly 
hoped  all  danger  was  past.  The  maximum  heat  on  record  for 
this  month  is  81:  it  occurred  in  1840  on  the  26tli,  The  lowest 
usual  range  is  28°  to  30°;  but  it  was  as  low  as  23  in  the  midland 
counties  in  1838. 
May  has  a temperature  varying  from  54°  in  the  south-east  to 
42°  in  the  north.  North-east  winds  generally  prevail,  and  the 
changes  of  temperature  are  great  during  the  month ; yet  its 
general  average  rarely  varies  more  than  2 from  the  mean.  This 
month  is  more  ungenial  in  our  climate  than  most  of  the  others. 
This  is  owing  to  the  east  winds,  which  are  during  this  month  dry 
and  cold  ; and  during  this  month  the  most  sensible  difference 
in  vegetation  and  the  heat  of  the  soil  is  observed.  Where  the 
land  has  been  deprived  of  its  surplus  water  by  an  efficient  drain- 
age vegetation  progresses  rapidly,  but  when  the  water  has  to  be 
evaporated,  languishes ; wheat  especially  turns  yellow,  and  rarely 
ever  recovers  the  check  thus  given  to  its  growth. 
June  has  a mean  temperature,  varying  from  62°  in  the 
south  to  50°  in  the  north,  and  in  Ireland  from  59°  in  the  south  to 
55°  in  the  north,  its  temperature  being  generally  higher  in  the 
eastern  than  in  the  western  counties.  At  the  Orkney  Islands, 
the  middle  of  June  is  frequently  nearly  as  cold  as  March,  owing 
to  the  prevalence  of  cold  northern  winds  ; and  it  is  not  till  the 
latter  end  of  this  month  that  vegetation  makes  much  progress  in 
those  islands.  The  temperatures  of  July  and  August  are  nearly 
the  same,  the  average  being  about  2°  above  that  ot  June.  During 
September  the  western  parts  of  the  British  Islands  have  a higher 
temperature  than  the  eastern,  and  during  the  whole  of  autumn 
that  superiority  is  maintained.  September  has  generally  a mean 
temperature  of  from  58°  in  the  south-east  to  60°  in  the  south- 
west, and  50°  in  the  north.  During  this  month  the  temperature 
of  the  soil  is  frequently  as  high  as  during  any  other  month  of  the 
year,  but  for  which  many  crops  would  never  arrive  at  maturity 
