22& Mu. Harvey on the FaU of Rain m tke Neighbourhood of Glasgow. 



XXXV. — On the FaU of Main in the Neighbourhood of Glasgow, 

 and Description of the Gorbals Gravitation Water Company's Works. 

 By Alexander Harvey, Esq. 



The valley of the Clyde is estimated by Dr. Thomson, in his work on 

 Heat and Electricity, to drain about l-30th part of Scotland, or about 

 l-83d part of Great Britain. He also states that the district drained by 

 the Clyde is not nearly so rainy as many other tracts both in England 

 and Scotland. The estimate, however, which he makes of the annual 

 fall of rain over the whole of Great Britain, as not less than 36 inches, 

 must be exceedingly near the truth, if we take into account many of the 

 districts, both in England and Scotland, where the fall of rain is consi- 

 derably under that quantity, along with the other districts which rise 

 considerably above it. 



I will not take up your time with any detail of the quantity of rain 

 falling in other districts, but will confine myself, as far as I have ascer- 

 tained it, to the fall of rain in different places situated in the strath or 

 valley of the Clyde, where of late rain guages have been kept, and 

 observed with considerable accuracy, and shall, for that purpose, present 

 you with a tabular view of the results obtained by the different ob- 

 servers : — 



Maximum. Minimum. Mean. 



Parish of Strathaven, Gilmour-} r n na A >- ork cone 



ton, by Mr. John Wiseman,... j 59 * 60 4rS0 68 * 6 



Parish of Mearns, by Mr. Mather, 7100 40-30 55.65 



Near Paisley, Mr. Stirrat, 72*00 42*00 57*00 



Ibroxholm, Mr. Gardner, 35*91 33*33 34.64 



Glasgow, Dr. Couper, from 1818) on 0£ > 



to 1834, J 2286 



Largs, 43-50 



Mean, 5964 40*73 4460 



It is difficult to account for the fall of rain at Glasgow being so much 

 le3S in quantity than at other places in the immediate neighbourhood, as, 

 for instance, at Ibroxholm, only two miles to the west of Glasgow, and 

 upon a lower level than even the college grounds where the rain guage 

 was kept. The guage at Ibroxholm shows a fall of rain of about one- 

 half more than the record kept by Dr. Couper shows at Glasgow. It is 

 now pretty well established that more rain falls upon high grounds than 

 upon low and level plains ; and this may be accounted for by the direc- 

 tion given to the currents of air, by the hills causing an intermixture of 

 the different strata of hot and cold air, thereby giving rise to a precipita- 

 tion of rain from the hotter stratum ; but why such a difference should 

 exist within so short a distance, at nearly the same level and in the same 

 strath, is, as I have already said, difficult to account for, unless we sup- 



