Ss SS 
aT 
a 
253 
in the first instance, becoming more and more drained as they 
advance eastward. The northern counties, too, in a general way 
have more rain than the southern from the configuration of the 
ground ; the hills and mountains which prevail in Scotland and 
the north-west of England, intercepting the course of the clouds, 
and causing much atmospheric disturbance with more frequent 
rains than occur in those parts of the country where the ground 
is comparatively but little raised above the sea. The Lake district 
is well-known as the wettest part of Great Britain the average 
yearly fall in one place there, the Stye, amounting to 165 inches 
whereas the average fall in the London district is scarcely more 
than 25 inches. 
Even in the same locality the rain-fall varies greatly in different 
years, some years having double or more than double the rain-fall of 
others. Consequently rain measurements require to be continued 
for a long period in order to determine the true average fall at 
any particular place. Sometimes the addition of a single year, if 
either a very wet or a very dry one, seriously disturbs the average as 
obtained from a decade of years preceding it. Hence the averages 
given in the following Tables must be received with caution until 
they have been confirmed or corrected by the observations of a 
longer period than the ten years to which they relate. Another 
circumstance also tends to throw doubt on the perfect accuracy of 
these returns, and that is the position of the rain-gauge in the 
Institution Gardens. Though the best that could be chosen under 
the circumstances, it is not wholly unobjectionable. Other 
buildings besides the Institution itself are very near, and taken 
together they must prevent, in certain states of wind and weather, 
some portion of the rain that falls from being received into the 
gauge. That such is sometimes the case seems to be shown by 
the fact of a second rain-gauge—placed several years ago fora 
time on the roof of the Institution—receiving more rain than the 
one down below in the garden. Making proper allowance for 
difference of elevation the result should have been j ust the reverse, 
4 i 
