194 NOTES ON THE SEASONS OF 1 893. 



surface became much drier and hotter than usual. On very fleet 

 springs this had a decided effect. In my own neighbourhood 

 (Felstead) our springs circulate at a depth of about twenty to forty 

 feet, and as the quantity of water in the river, which niight be 

 described as wholly derived from the springs, remained constant 

 (with one exception, to be presently noticed), we could not observe 

 that the springs were affected. The time of greatest scarcity of 

 river water is usually October and November, but this year no 

 scarcity has been noticed. We therefore conclude that the present 

 supply is due to rains preceding the drought, that is, not later than 

 February, and we also infer that the summer rains do not materially 

 affect these deeply-seated springs. 



The one exception to the normal flow of the river was due to 

 the hot days of August. I am indebted to the miller at Felstead 

 for the following observation : Immediately upon the advent of those 

 few hot days there was a marked diminution in the river supply, 

 the " head " being exhausted in about three-quarters of its ordinary 

 time ; but on the arrival of cooler weather the full supply again 

 returned, and this without any rain having fallen, so far as is known, 

 within the area of drainage. This phenomenon could only have 

 been due to the excessive evaporation caused by the sun. It is 

 certainly very unusual to have the opportunity afforded in Essex of 

 getting a direct measure of the influence of the sun's rays in causing 

 evaporation. It may be here obtained to a near approximation, 

 because the daily quantity of water passing the mill is well known, 

 and a loss of a quarter of that quantity represents the total loss on 

 the whole surface of the stream up to its source. This bearing but 

 a very small proportion to the drainage area, it becomes apparent 

 that the force of the sun's rays in causing evaporation must be very 

 great indeed ; and it moreover shows that the quantity of water 

 discharged by the leaves of plants must be considerable in volume. 

 This great volume of water (escaping as vapour) and the flow of 

 the river throughout the summer is the measure of the demand, less 

 a small portion of the rainfall, which has been made upon the spring 

 since last February. We are not concerned to go further into the 

 subject here ; we have only noted the good opportunity afforded by 

 the season to deal with some approximation with that subject. 



It remains to consider whether any permanent effects may result 

 from this extraordinary summer. 



Our experience of the past leads us to suppose that there will be 



