on the Climate and Agricultare of the Britisli Isles. 53 
vovj nearly ccjual to the mean lieat in tlic air over tlie land ; 
but, driven onwards over the hilly surface of the westi-rn high- 
lands, it meets with a colder stratum, and the chilled night air 
also tends to condense the vapour and produce an abundance of 
rain. In such a season cloud on cloud rolls in from the west 
till masses of vapour obscure the sun, which day after day no 
ray of his can pierce ; them, long pendant streams of condensing 
vapour float over the languishing ears of corn, or descend in 
hi-'avy rain to injure and retard the harvest. 
But there are seasons when, under the influence of the clear 
sl<y of the east wind of spring, the soil becomes so heated by the 
solar rays that the radiation of heat from the land becomes more 
than a match for the vanour from the sea. The sun has obtained 
the mastery, and it gives him the means and the power to main- 
tain it. Then the summer is of the most genial character, and 
the heat is tempered by the fresh balmy breeze from the west. 
Such was the July of 1859, when my thermometer in the shade 
by day generally stood at 80°, and once, on the 12th, at 94°, 
The wheat harvest began on the 20th, and before the end of the 
month much corn was cut. August commenced with heavy 
rain : upwards of an inch fell in one day, and the highly-heated 
soil became a hotbed of wondrous activity. 
The effect of the north-east wind of spring on the temperature 
of the succeeding summer is well illustrated by this great heat 
i« 1859. In that year, during the whole of February and March, 
the wind was from the westerly points of the compass ; but late 
in April the return current from the north-east set in and con- 
tinued with great constancy throughout the whole of May, and 
in this month not a single point of westerly wind was marked 
by the vane at Greenwich. The following months of June and 
July were respectively 2 2° and G'2° above their average tempera- 
ture. The masses of vapour which the winter winds had rolled 
in from the Atlantic had been driven back by the steady per- 
sistency of this dry wind from northern Europe ; the sky was 
kept clear of cloud and the sun's rays fell unobstructed on the 
heated soil, the radiations from which so warmed the air that 
tile summer humidity from the sea was absorbed by its higher 
capacity for moisture, and invigorating open sunshine continued 
throughout most of the summer. At such a season I have seen 
the mist and clouds from the sea " eaten up " by the warmer air 
over the land. The westerly wind brought the visible moisture 
to the line of contact with the warmer air on the Cornish coast ; 
but there it broke into streaks of white vapour, and disap- 
peared like the steam from the funnel of a railway locomotive 
-engine. 
