RAIN. 



to any miftake, but to the conflant elfeft of feme circum- years afterward, Daines Barrington, efq. made the foUow- 



ftance vvliicli, not being fuppofed to be of any moment, had ing experiments and obferyatioiis, to fhew that this efi'eft, 



never been attended to. The rain-gage in one of thefe witli refpedl to different places, refpedted only the feveral 



places was fixed fo higli, as to rife above all the neighbouring heights of the inftruments above the ground at thofe places, 



chimnies ; the other was confidcrably below them ; and without regard to any real difference of level in the ground 



there appeared realon to believe, that the diflcrence in the 

 quantity of rain in thefe two places was owing to this dif- 

 ference in the placing of the vellel in which it was received. 

 A funnel was, therefore, placed above the higheft chimnies, 

 and another upon the ground of the garden belonging to 

 the fame houfe, and there was found the fame difference 

 between thefe two, though placed fo near one another, 

 which had been between them, when placed at fimilar 

 heights in different parts of the town. After this faft was 

 fufhciently afccrtained, it was thought proper to try whether 

 the difference would be greater at a much greater height ; 

 and a rain-gage was therefore placed upon the fquare part 

 of the roof of Weftminfler Abbey. Here the quantity of 

 rain was obferved for a twelvemonth, the rain being meal ured 

 at the end of every montii, and care being taken that none 

 Ihould evaporate by paffing a very long tube of the funnel 

 into a bottle through a cork, to which it was exaftly fitted. 

 The tube went down very near to the bottom of the bottle, 

 and therefore the rain whi.ii fell into it would foon rife 

 above the end of the tube, lo that the water was no where 

 open to the air except for the fmall fpace of the area of the 

 tube : and by trial it was found that there was no fenfible 

 evaporation through the tube thus tilted up. 



The following table fhewsthe refult of thefe obfervations. 



at thofe places. 



Mr. Barrington caufcd two other rain-gages, exaftly 

 like tliofe of Dr. Hebcrden, to be placed, the one upon 

 mount Rennig, in Wales, and the other on the plane below, 

 at about half a mile's diflance, the perpendicular height of 

 the mountain being 450 yards, or 1350 feet ; each gage 

 being at the fame iieight above the furface of the ground 

 at the two itations. 



The refults of the experiment are as below : 



From July the 7th, 1766, to July the 7th, 1767, there fell 

 in a Rain-gage, fixed 



1766. 



From the 7th to 

 the end of July 

 Augufl 

 September 

 Oftober 

 November 

 December 



1767, January 

 February 

 March 

 April 

 May 

 June 

 July 7 



Below the top 

 of a houfe. 



Upon the top 

 of a houfe. 



22.628 



Upon Weft- 

 ninfter Abbey 



Inches. 

 2. 311 



I 0.508 



1. 416 

 0.632 

 0.994 



I-C35 

 1-335 

 0.587 

 0.994 

 1. 142 



" The inference to be drawn from thefe experiments, 

 Mr. Barrington obferves, feems to be, that the increafe of 

 the quantity of rain depends upon its nearer approximation 

 to the earth, and fcarcely at all upon the height of places, 

 provided the rain-gages are fixed at about the fame dif- 

 tance from the ground. 



" PofTibly alfo a much controverted point between the 

 inhabitants of mountains and plains may receive a folution 

 from thefe experiments ; as in an adjacent valley, at leaft, 

 very nearly the fame quantity of rain appears to fall within the 

 fame period of time as upon the neighbouring mountains." 



Dr. Heberden alfo adds the following note. " It may 

 not be improper to fubjoin to the foregoing account, that, 

 in places where it was tirft obferved, a different quantity of 

 rain would be coUeftad, according as the rain-gages were 

 placed above or below the tops of the neighbouring build- 

 ings ; the rain-gage below the top of the houfe into which 

 the greater quantity of rain had for feveral years been 

 found to fall, was above fifteen feet above the level of the 

 other rain-gage, which, in another part of London, was 

 placed above the top of the houfe, and into which the leffer 

 quantity al.vays fell. This difference, therefore, does not, 

 as Mr. Barrington juftly remarks, depend upon the greater 

 By this table it appears, that there fell below the top of quantity of atmofphere through which the rain defcends : 

 a houfe above a fifth part more rain than what fell in though this has been fuppofed by fome, who have thence 

 the fame fpace above the top of the fame houfe ; and that concluded that this appearance might readily be folved by 

 there fell upon Weftminfler Abbey not much above one- the accumulation of more drops, in a defcent through a 

 half of what was found to fall in the fame fpace below the great depth of atmofphere.'' 



.145 



18.139 



12.099 



tops of the houfes. This experiment has been repeated in 

 other cafes with the fame refult. What may be the caufe 

 of this extraordinary difference, has not yet been dif- 

 covered ; but it may be ufeful to give notice of it, in 

 order to prevent that error, which would frequently be 

 committed in comparing the rain of two places without 

 attending to this circumftance." 



Such were the obfervations of Dr. Heberden on firfl 



In the examination of the refults from meteorological 

 tables, it (hould be obferved, that feveral years' account of 

 the rain at any place is required, before a medium yearly 

 quantity can be obtained with fufficient accuracy. The 

 following table, formed by Mr. Dalton, and pubhfhed in the 

 tirfl part of the fifth volume of Manchefler Memoirs, gives 

 us the largefl coUeftion of accounts of rain fallen in dif- 

 ferent places in England that has to our knowledge hitherto 



announcing this circumflance, T'iz. of different quantities of appeared. They are chiefly taken from the Tranfaftions of 

 rain falling at different heights above the ground. Two the Royal Society, and of other focieties. 



Cumberland 



