RAIN. 



The general mean of 35.2 inches is, as our author appre- 

 hends, a little above the medium for England and Wales, 

 as the greater number of places are thofe where much rain 

 falls. If we take up a mean for each of the above-mentioned 

 counties, (where more than one place in a county is given,) 

 and then a general mean from the counties, the refult is a 

 reduced mean of 31.3. Even then it may be objected, that 

 the greater part of the counties are maritime ; but it muft 

 be obferved, that there is no account of rain in Wales ; and 

 we may fafely conclude, that the rain in Wales would ex- 

 ceed the lail-mentioned mean as much as the inland counties 

 of England, not in the above lift, would fall (hort ; becaufe 

 Wales is both a mountainous country, and expofed to the 

 fea. 



We will, therefore, conclude, that the mean annual depth 

 of rain in England and Wales, deduced from thefe twenty 

 counties, is 31 inches: a quantity which fublequent ob- 

 lervations, our author is confident, will not diminifh, and 

 probably not increale much. 



The editors of the Encyclopedia, under the article 

 Weather, from 16 places of obfervation, make the annual 

 mean for Great Britain 32.53 inches; and M. Cotte, in the 

 Journal dc Phyfique for 1791, gives a mean derived from 

 147 places, in different parts of the world, equal to 34.7 

 inches. 



If we take the dew (fee Dew) at 5 inches annually, we 



fliall have 36 inches of water at a medium annually, on the 

 furface of the earth, in England and Wales, reckoning 31 

 for rain and 5 for dew. Admitting the computation of 

 Guthrie, the area of England and Wales is 46,450 fquare 

 miles. This, reduced to Iquarc Ret, gives 1,378,586,880,000; 

 wh:ch, multiplied by 3 feet, the annual depth of rain and 

 dew, gives 4,135,760,690,000 cubic feet of water, = 

 153.176,320,000 cubic yards, or 28 cubic miles =. 1 1 c 

 thoufand millions of tons in weight, nearly. This immenfe 

 mafs of water is difpofcd of partly by the fupply of rivulets, 

 and the foaking into the earth a (mail way, lo as to break 

 out again in lower ground in the form of fprings, and 

 thence make ics way to fome river, by which it is conveyed 

 to the fea; and partly by being raifed nito the atmofjjhere 

 in the procefs of evaporation. The decompofition of water 

 by vegetables is not noticed, becaufe it is prelumed, that 

 in the courfc of nature the principles are combined, and 

 water formed again. See RivER, Spring, Evaporation, 

 and Vapour. 



As to the ufe of rain, we may obferve that it moiftens 

 and foftens the earth, and thus fits it for affording nourifh- 

 ment to plants : by falling on high mountains, it carries 

 down with it many particles of loofe earth, which frrve to 

 fertilize the furrounding valli>s, and purifies the air from 

 noxious exhalations, which tend in their return to the earth 

 to meliorate the foil ; it moderates the heat of the air ; and 

 is one means of fupplying fountains and rivers. However, 

 vehement rains in many countries are found to be attended 

 with barrennefs and poornefs of the lands, and mifcarriage 

 of the crops in the fucceeding year : and the rcafon is plain ; 

 for thefe exceffive itorms wafh away the fine mould into the 

 rivers, which carry it into the fea, and it is a long time be- 

 fore the land recovers itfelf again. The remedy to the fa- 

 mine, which fome countries are fubject to from this fort of 

 mifchief, is the planting large orchards and groves of fuch 

 trees as bear efculent fruit ; for it is an old obfervation, that 

 in years, when grain fuccecds worlt, thefe trees produce 

 moll fruit of all. It may partly be owing to the thorough 

 moillening of the earth, as deep as their roots go, by thefe 

 rains, and partly to their trunks flopping part of the light 

 mould carried down by the rains, and by this means fur- 

 niftiing themfelves with a coat of new earth. Phil. Tranf. 

 N" 90. 



The water afforded by rain is found highly refrefhing to 

 almoft all forts of vegetable crops, and to promote tlieir 

 growth in a rapid manner, when not produced in too great 

 abundance at a time. This efieft, which may often be per- 

 ceived to take place in a fudden manner, after warm {howers 

 in the early fpring months, is probably caufed by the large 

 proportion of oxygen that is contained in rain-water, as well 

 as from the ncceiiary moifture being afforded to the fibres of 

 the roots of the plants. Too much rain may be injurious, 

 however, by leffening the neceffary cohefion and compaft- 

 nefs of foils, by which they may not afford proper firmnefs 

 to the roots of growing vegetables. And another injury 

 may be produced by the too frequent occurrence of hafty 

 fhowers, by which a large proportion of the decompofing 

 vegetable and animal materials of lands, which are foluble 

 or diffufible in water, may be conveyed away into the 

 ditches, rivers, and ultimately into the fea, and of courfe 

 prove the caufe of infertility. In hilly fituations, this effedl 

 may arife from even flight fhowers ; on which account, they 

 have been advifed to be ploughed in a flanting diredlion, as 

 by that means the rains may be more perfectly detained in 

 the foils. And it has been iuggelled by Dr. Darwin, that 

 as the foliage or buds of plants require more moifture for 

 their vigorous growth than their flowers, in this climate, 

 continued rains may be liable not only to wafli off the farina 

 1 from 



