The climate of a country, however, depends not only upon the sunshine, but upon the rainfall. The amount of rain that falls in any place varies according to the height of that place above the sea, its distance from the coast, and the configuration of the ground, that is to say, upon its position with respect to valleys, up which moisture-laden air may be driven by the wind, to be compressed and cooled until its moisture falls in rain. The rainfall varies very much in different parts of England, but the average amount for the whole country is about 33 inches in a year. When we speak of an inch of rain we mean that it would lie an inch deep on a perfectly level piece of ground. Thus, if all the rain that fell in a year stayed on the ground, and did not evaporate, or run away, or sink into the earth, the water would be 33 inches deep all over England at the end of the twelve months. An inch of rain all over an acre of ground weighs rather more than 100 tons. Not only does the rainfall vary in different parts of the country, but it varies in different years. The wettest year on record was 1903, when the rainfall averaged 50 inches for the whole of England; and the driest year was 1887, when it amounted to no more than 24 inches. The heaviest rainfall in Great Britain is in the mountains round Ben Nevis and Snowdon, in the English Lake District, and in the uplands of Cornwall and Devon. And it may fairly accurately be said that, as we cross England from west to east, the amount of the annual fall steadily decreases, as is shown in the accompanying map. The moisture-laden clouds, driven across the Atlantic by the prevalent S.W. winds, discharge their contents on meeting the cold high lands of western England, which thus act as a sort of umbrella, the driest parts of the country being on the east coast. While the average fall over a considerable part of the west side of it is from 40 to 60 inches, that on the east is no more than from 25 to 30; and round the Wash and in parts of Suffolk and Essex it is under 25 inches. Thus it sometimes happens that when the west of England has rain enough and to spare, the eastern districts are suffering from the want of it. The effect of this difference is shown in a marked degree in the character of the crops. The farms of the rainier west are to a great extent laid down in grass. The drier districts of the east grow more corn, which needs dry weather to ripen it. [Illustration: ENGLAND & WALES ANNUAL RAINFALL (_The figures give the approximate annual rainfall in inches._)] The driest month in England generally is March, whose rainfall averages 1·46 inches; and the wettest is October, in which the average amount is 2·81 inches.