G-i On the Temperature of the Sea, and its Injiuence 
feet above the sea ; and on tlie low lying lands at Taunton 28 
inches. 
The favoured vale of Taunton Dean, defended by the Ex- 
moor hills on the west from excessive rainfall, has a high sum- 
mer temperature, and a rich red-sandstone soil. Sheltered by 
hills on every side, it may be considered the wall-garden of the 
west, and when loaded with autumn fruit and corn, and the 
pastures studded with heavy cattle, it looks like a picture of 
agricultural plenty set in a frame-work of massive hills. 
The third line of gauges, from the sea-coast at the Somerset 
marsh lands on the west, tells precisely the same story as the 
other lines. The rainfall from the sea inland increases 60 per 
cent, on the crest of the hills, which form the water-shed of the 
valley from Bruton to Shepton Mallet; the accumulation of 
rain from these upper slopes often floods and injures the rich 
marsh lands below, and overpowers the capabilities of the en- 
gineering works which have been constructed for the drainage 
of the levels. Such works should be adapted, not only to the 
actual rainfall on the land to be drained, but also to the floods 
resulting from the direction of the rain-bearing wind, and the 
condensing power of the neighbouring hills. 
On the high chalk table-land of Salisbury Plain, and east- 
ward to beyond Winchester, much less rain falls than would 
be inferred from a country lying at a height of from 400 to 
600 feet above the sea. My gauge at Chiltern-All-Saints gave 
an annual mean of only 23 inches ; and the returns obligingly 
sent me from Itchen Abbas, at the eastern end of the plateau, 
only 28 inches. Descending eastward to the low lands of the 
open valley of the Thames, the long-continued observations at 
Cobham, Chiswick, and Greenwich, give 24 inches as the 
average rainfall over a large area. 
It appears that the unequal distribution of rain in the west 
mainly results from the difference of elevation of the land, and 
of the form and slope which the surface presents to the rain 
depositing wind. The warm, moist air is driven up the sides 
of the hills, and mingles with a colder stratum at a higher 
altitude ; and as it approaches the line of contact the conden- 
sation becomes more rapid, and thus there is a large increase in 
the i-elative amounts near the head of the valley. We shall illus- 
trate this by a few examples. 
The south-west wind strikes into the funnel-mouthed bay of 
Carnarvon with great power, dropping from 30 to 40 inches of 
rain on the coast-line ; passing up the valley to the foot of 
Snowdon at 330 feet high the amount is increased to 113 inches, 
and at 1300 feet to 127 inches ; but it by no means follows that 
the depth of rain is proportionate to the height of the station; 
