=119. Laws of Rain-fall.=--Tropical countries have a dry and a wet season during the year: _dry_, when the sun is at the opposite side of the equator; _wet_, when the sun is overhead. With reference to the British Isles, the statistics collected by Mr. G. J. Symons indicate that: 1st. The stations of least rain are inland, or on the east or south-east coasts; the stations of greatest rain are on the western coasts. 2nd. The rain-fall is very large in the vicinity of mountain chains or groups, unless the station happens to be some miles to the north-eastward. It may be well to illustrate these remarks by quoting[12] the average fall at a few places, grouping them as-- Westerly. Inches. Bodmin 43 Bolton (Lancashire) 44 Coniston (Windermere) 71 Seathwaite 127 Torosay (I. of Mull) 75 Killaloe (Limerick) 38 Central. Inches. Enfield 23 Epping 23 Derby 24 York 22 Stirling 39 Perth 29 Easterly. Inches. Witham (Essex) 21 Patrington (Hull) 21 Sunderland 17 Inveresk (Edinburgh) 25 Pittenweem (Fife) 24 Dublin 22 Mr. Green, the celebrated aeronaut, has asserted from his experience, "that whenever a fall of rain happens, and the sky is entirely overcast, there will invariably be found to exist another stratum of cloud at a certain elevation above the former;" and the recent scientific balloon ascents by Mr. Glaisher have tended to confirm this theory. Mr. Glaisher says, "It would seem to be an established fact, that whenever rain is falling from an overcast sky, there is a second stratum above." "It would also seem that when the sky is overcast without rain, that there is no stratum of cloud above, but that the sun is shining on the upper surface. In every instance in which I have been up under these circumstances, I have found such to be the case, agreeing in this respect also with Mr. Green's observations." The amount of rain collected in a gauge placed near the surface of the earth is larger than in any gauge placed above it; and the higher the gauge is placed, the less water is collected. Mr. Glaisher contends that his balloon experiments corroborate this law.