641 
in  its  Effect  on  Cultivation. 
The  preceding  tables  will  give  a graphic  idea  of  the  annual 
distribution  of  rain  during  the  year,  and  it  will  be  seen  that,  as 
might  have  been  expected,  the  greatest  quantity  of  rain  falls  during 
months  when  the  greatest  quantity  of  moisture  is  in  the  air,  or 
when  the  dew  point  is  nearest  the  mean  temperature  of  the  air. 
Thus  the  rain  of  the  last  six  months  of  the  year  is  to  that  in  the 
first  six  nearly  as  3 to  2.  The  following  is  the  average  fall  of  rain 
taken  during  a great  number  of  years  at  places  situated  in  the 
British  Islands : — 
Places  on  the  Eastern  side. 
Places  on  the  Middle. 
Places  on  the  Western. 
Inches. 
Inches. 
Inches. 
London  . 
. . 20-7 
Chatsworth  . 
. 27-6 
Falmouth 
. 42-8 
Eppina:  . 
. . 26-0 
Empingham  . 
. 25-1 
Liverpool 
. 34-4 
Boston 
. . 20-1 
Retford  . 
. 24-0 
Manchester  . 
. 36-1 
Edinburgh 
. . 22-2 
Cambridge  . 
. 25-0 
Lancaster 
. 39-7 
Dundee  . 
. 21*6 
Lincoln  . 
. 24-0 
Kendal  . 
. 53-9 
Aberdeen  . 
. . 20-8 
Dumfries 
. 36-9 
Argyleshire  . 
. 40-4 
Keswick  . 
. 62-4 
From  the  above  it  is  seen  at  once  that  the  most  rain  falls  in  the 
west,  but  less  on  the  western  coast  where  sheltered  by  Ireland,  as 
Liverpool  and  Manchester,  whilst  places  higher  than  can  be 
affected  by  Ireland  again  show  an  increase,  as  Kendal  and  Argyle- 
shire. 
In  Ireland  there  fall  on  an  average  at  Dublin  23‘8  inches,  at 
Cork  39  • 8 inches,  and  at  Londonderry  30  inches. 
I now  come  to  a very  important  part  of  the  subject,  viz.,  the 
signs  of  the  approach  of  rain. 
It  is  generally  considered  that  after  the  moisture  of  the  air  is 
condensed  in  the  form  of  clouds,  it  is  the  withdrawal  of  electricity 
that  causes  the  condensed  vapour  to  form  drops,  and  then  bv  its 
specific  gravity  fall  to  the  ground  in  rain.  But  it  is  quite  certain 
that  much  that  is  spoken  and  written  on  the  subject  of  electrical 
action  is  only  another  way  of  confessing  ignorance,  and  after  care- 
fully considering  the  subject,  I think  that  generally  on  the  subject 
of  rain  it  would  be  quite  as  philosophical  to  impute  the  discharge 
of  electricity  to  the  formation  of  rain,  as  to  impute  rain  to  the 
withdrawal  of  electricity.  Cold  condenses  vapour  into  mist  and 
clouds;  as  this  condensation  proceeds,  water  begins  to  fall,  first 
slowly  and  in  very  minute  particles,  but  as  it  continues  to  descend 
each  drop  increases  in  size  by  combining  in  its  descent  with  the 
vapour  in  the  air,  and  thus  grows  larger  as  it  approaches  the 
earth.  Thus,  though  it  rains  oftener  in  high  and  mountainous 
countries  than  in  low  ones,  yet  if  a rain-gauge  be  placed  on  the 
ground  and  another  at  some  height  in  the  air,  the  gauge  on  the 
