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41
possess the fullest acquaintance with the watershed, we propose
to adopt his figures. From Mr. Topley we accept 3,548
square miles as being approximately the area above the intakes
of the Water Companies. Mr. More has put in gaugings of
the discharge of the Thames at Teddington for the years 1883
to 1891 with an added column showing the rainfalls.
" In the third column of the table the average yearly discharge
of the nine years at Teddington is given as
435,931,000,000 gallons. But this quantity is subject to some
correction, for we found on investigating the details of the
gauging atrangements at Teddington that it was desirable to
check the results by simultaneous measurements at Molesey and
Sunbury Weirs, and having entrusted this work to Mr. Middleton
and considered his report we accept his opinion that Mr.
More's quantities should be increased by 7 per cent. To the
435,931,000,000 gallons we therefore add 30,515,170,000 gallons,
making 466,446,170,000 gallons. To this again must be added
the average quantity taken by the Companies, viz., 30,896,000,000
gallons, giving a grand total of 497,342,170,000 gallons. Divided
by 365 this gives a daily average of 1,362,581,288 gallons.
Year.
Total Quantity of
Water abstracted by
the
Water Companies.
Volume ot Discharge
at Teddington Weir
as guaged by the
ThamesConservancy
Total flow of
River Thames
Col. 2 x Col. 3.
Average Annual
rainfall on
Thames Basin
above intakes of
the Water
Companies.
Gallons. Gallons. Gallons. Inches.
1883 26,197,000.000 659,657,000,000 685,584,000,000 28.41
1884 29,946,000,000 330,648,000,000 360,594,000,000 22.90
1885 29,654,000,000 339,130,000,000 428,784,000,000 29.15
1886 30,350,000,000 544,786,000,000 575,136,000,000 31.07
1887 32,154,000,000 390,296,000,000 422,450,000,000 21.32
1888 30,280,000,000 427,656,000,000 457,936,000,000 28.45
1889 31,419,000,000 437,059,000,000 468,478,000,000 25.64
1890 32,876,000,000 261,916,000,000 294,792,000,000 22.81
1891 35,185,000,000 472,228,000,000 507,413,000,000 33.31
Total 278,061,000,000 3,923,376,000,000 4,201,437,000,000 243.06
Average
of the
9 years
30,895,000,000 435,931,000,000 466,827,000,000 27.01
“But during the nine years in question the rainfall averaged
only 27.01 inches as compared with 28.50 inches which Mr.