148 PROCEEDINGS OF THE COTTESWOLD CLUB 



contains water with only 3 grains of total solids in the 

 gallon, gradually picks up a little carbonate and sulphate 

 of lime, and so increases in hardness as it progresses. 

 The tributaries it receives between the Vyrnwy and the 

 Avon, excepting the Teme, bring in water containing a 

 comparatively large quantity of solid material, but they 

 are all quite small compared with the main stream, and 

 the water consequently remains pure and soft in the 

 Severn until it arrives at Tewkesbury. Some people 

 appear to entertain the idea that the water of the 

 Severn must contain a large quantity of solid impurity 

 after so long a flow. The fact of the country through 

 which it passes being cultivated, it has been hinted, must 

 add material to it. This is a great flillacy. The green 

 meadows of Severnside are not a source of pollution, and 

 the actual amount of solid material in the Severn at 

 Tewkesbury only appears to average about 12 grains in 

 the gallon, which is a far smaller amount than that con- 

 tained in any other natural water in the neighbourhood. 

 The average hardness is about 8 degrees, but varies some 

 degrees on either side of this. The last sample obtained 

 only a few days ago, had 5^ degrees only. Even when 

 the water is very turbid, as after long continued rains, 

 the material which causes the turbidity has very little 

 weight, the whole solid material rarely exceeding, under 

 these conditions, more than 20 grains per gallon. The 

 turbidity of the water at Tewkesbury is caused by fine 

 particles of sand and red marl, and there is more of one 

 or of the other according to the locality where the 

 greatest rainfall has occurred to disturb the banks of the 

 tributaries. The Teme, when in flood, brings in more red 

 marl than any other tributary, and this causes thick red- 

 ness in the water of the Severn. The waters of the 

 upper Severn have a slight turbidity after rain, which is 

 said to be due to kaolin ; the suspended material is im- 

 palpably fine, and when the rains have been confined to the 



