1896.] on the Past, Present and Future Water Supply of London. 73 



These samples were collected on December 11, 1895.* The reduc- 

 tion here being not so great, partly on account of the shorter storage, 

 but chiefly because the New Eiver Cut, above the point at which the 

 samples were taken, is itself a storage reservoir containing many 

 days' supply. Indeed, quietness in a subsidence reservoir is, very 

 curiously, far more fatal to bacterial life in river-water than the 

 most violent agitation in contact with atmospheric air : for the 

 microbes which are sent into the river above the falls of Niagara 

 by the city of Buffalo seem to take little or no harm from that 

 tremendous leap and turmoil of waters ; whilst they very soon almost 

 entirely disappear in Lake Ontario. 



Thus it is not too much to expect that storage for, say a couple of 

 months, would reduce the number of microbes in Thames flood water 

 down to nearly the minimum ever found in that river in dry weather ; 

 whilst, by avoiding the first rush of each flood, a gcod chemical 

 quality could also be secured. There is therefore, I think, a fair 

 prospect that the quantity of water derivable from the Thames at 

 Hampton could be increased from its present amount (120 millions of 

 gallons per diem) to 370 millions. 



Again, in the River Lea, although here the necessary data for 

 exact calculation are wanting, it may be assumed that the present 

 supply of 54 millions of gallons could be increased by the storage of 

 flood water to 100 millions of gallons per day. To these volumes 

 must be added the amount of deep-well water which is obtainable 

 from those parts of the Thames basin which lie below Teddington 

 Lock, and in the Lea basin below Lea Bridge, and which was esti- 

 mated by the last Royal Commission appointed to inquire into the 

 water supply of the metropolis, at rather more than 67^ millions of 

 gallons. 



Thus we get the grand total of 537J millions of gallons per day 

 of excellent water obtainable within the Thames basin, the quality 

 of which can be gradually improved, if it be considered necessary, by 

 pumping from the water-bearing strata above Teddington and Lea 

 Bridge respectively, instead of taking the total supj)ly from the 

 open rivers above these points. Such a volume of water would 

 scarcely be required for the supply of the whole water area of London 

 at the end of fifty years from the present time, even supposing the 

 population to go on increasing at the same rate as it did in tlie decade 

 1881-91, which is an assumption scarcely likely to be verified. 



In conclusion, I have shown that the Thames basin can furnish 

 an ample supply for fifty or more years to come, whilst the quality of 

 the spring and deep-well waters and the filtered river water would 



* All the bacteriological illustratious used in this discourse were photographs 

 taken by Mr. Burgess from tJie actual growtlis on the gelatine plates; and 

 my be.-t thanks are due to him for the veiy skilful execution of this difificidt and 

 delicate work, involving, as it di^l in many cases, the "svalching of the cultivations 

 from hour to hour. 



