The _latitude_ of a place has a great influence. As a rule the rainfall decreases with increasing distance from the equator; but local conditions may produce great modification, or even alterations of this law. The _elevation above the sea-level_ has a varying influence. In the Swiss Alps it is said that the rainfall increases with the elevation; but this rule does not hold good in America. The _nearness of large surfaces of water_ in summer tends to increase the rainfall, when water is colder than its surroundings, while in winter it has the opposite effect. The neighbourhood of the sea is for the west of England and islands adjacent, a cause of increased rainfall. The _influence of winds_ on the rainfall has been already considered. In Great Britain south-west winds more especially increase the rainfall. In their course they have travelled over the Gulf Stream and the general equatorial current, and have thus received warmth and moisture. The condensation of their moisture liberates a large amount of latent heat, thus raising the temperature of this country. In summer, however, south-west winds are _cool_ and moist, as the Atlantic is not so hot as the continents of Asia and Europe over which other winds have travelled. In England the average rainfall is about 33 inches, in Scotland 46, and in Ireland 38 inches. In the east of Great Britain, the rainfall is from twenty to twenty-eight inches. On the west coasts of Scotland and Ireland it is from 60 to 80 inches; and in some parts of Cumberland may be about 150 inches per annum. The annual rainfall varies greatly from the average for a number of years. In this country it has been estimated that the maximum annual rainfall exceeds by one-third, and the minimum annual rainfall is less by one-third than the average rainfall of a series of years. The _number of rainy days_ by no means corresponds with the amount of rainfall. There are fewest rainy days at the equator, where the rainfall is greatest. The rain diminishes the relative humidity of the air, and purifies it from dust. CHAPTER XXXV. METEOROLOGICAL OBSERVATIONS. The Royal Meteorological Society recognises stations for the making and recording of observations of three kinds: (1) _Second Order Stations_, at which observations are taken twice daily at 9 a.m. and 9 p.m.; (2) _Climatological Stations_, at which the observations are taken once daily, at 9 a.m.; (3) Stations at which _one or more elements only_, _e.g._ rainfall, _are observed_. All instruments used should have been previously verified at Kew Observatory, so that the corrections for index error may be known. The =Barometer= used should be of a standard kind. Five chief kinds of barometer are in use, only the last two of which are sufficiently accurate for scientific purposes.