CHAPTER Xx: 
‘THE EFFECTS OF SUNLIGHT CONTINUED: THE RESULTS OF 
ANALYSES OF THE WATER OF LAKES AND RESERVOIRS 
IN INDIA. 
A THIRD source from which the action of sunlight and 
storage can be demonstrated, is by a study of the results of 
analyses obtained from the various impounding reservoirs, 
lakes, and storage tanks, taken at different times of the year, 
and considering these in relation with the meteorological con- 
ditions obtaining at the time. In the Madras Presidency 
7 out of 18 water-works derive their supply from lakes; 2 
others, namely, Kurnool and Cocanada, possess storage res- 
ervoirs, which for 9 months of the year are used as settling 
tanks only, holding about 6 or g days’ supply ; but which at 
the commencement of the hot weather are pumped ful, and 
act as storage reservoirs for the town, containing as much 
as 24 to 3 months’ supply, for the period when the irrigation 
canals are empty. The results obtained in these 2 storage 
reservoirs have been included in these returns. 
In order to save long descriptions Tables IX (a) and IX (6) 
hhave.been compiled. 
It is necessary to make a few remarks about the meteor- 
ological conditions obtaining in each quarter :— 
(x) Quarter ending 30th September 1908. During these 
three months no rain had fallen in any of the towns given in 
Table IX (a), for many months prior to the taking of the 
samples, with the single exception of Ootacamund. All the 
storage reservoirs were extremely low; Adoni, Ootacamund 
and Vizagapatam were extremely short of water. Conse- 
quently the analyses give the results of waters that have 
been exposed to sunlight for a great length of time, in no case 
less than 6 months. 
(2) Quarter ending 31st December 1908. In practically 
every town more or less rain fell during this quarter. In 
most particularly at Vellore, Ootacamund, Coonoor, Madras 
