256 MR. A. G. INNES ON TIDAL ACTION IN 
at Horning was due to “ backed-up ” water from the Thurne 
River and not to Yarmouth sea-water. Yarmouth sea- water 
may contain sewage, whereas the Thurne waters are not 
appreciably contaminated ; hence, if the salt found could be 
shown to have come from the Thurne River its presence need 
not be regarded as a sign that the water is unfit to drink. 
To establish this Mr. Lincolne Sutton made simultaneous 
tests at Thurne Mouth. Samples were taken every hour at 
each of three stations, one on the Thurne River and one on 
the Bure — both above the junction, while the third was on 
the Bure below the junction. Mr. Sutton said (Minutes 
of Evidence, Great Yarmouth Waterworks Bill, House of 
Commons, July 20th, 1906, p. 104), “The first series, which 
I took in January (1906), proved most conclusively that 
the Thurne waters back up towards the intake and affect 
the minor variations in salinity at that point.” 
Describing the tests made by him on January 28th, 1906, 
Mr. Sutton said (ibid., p. 105), that at the middle of the ebb 
(5 p.m.), “The salinity of the Thurne was 14.7, and of the Bure 
towards the intake 4.9, and of the mixed waters 9.2. 
“ A little later, at the bottom of the ebb, the salinity of the 
Thurne rose from 14 to 19, the Bure towards the intake was 
5.6 only, and the mixed waters 9.2. When we get to the next 
period, ix p.m., at the beginning of the flow, when the tide 
had turned, and was beginning to bring back the mixed water, 
some flowing up the Thurne River, and some towards the 
intake, we find the salinities practically identical, 8.4, 8.2, 
and 8.7. So that the salinity towards the intake had risen from 
4.9, the first test, to 8.2, conclusively due entirety to the 
influence of the Thurne water.” 
In the tests made in February, 1906, “ the salinity of the 
Thurne was as high as 32. It was increased from 12 at the 
beginning of the ebb, and the water came down to 32 at the 
bottom of the ebb, while the salinity towards the intake was 
in one case 6.4 and in the other 3.8. That is to say, the 
ebb down the Bure towards Thurne Mouth reduced the salinity, 
while the ebb down the Thurne towards the sea raised the 
salinity.” 
