248 MR. A. G. INNES ON TIDAL ACTION IN 
The results show the state of the river on various 
dates, and with the tide at various stages of the ebb and 
flow. 
As one follows the change in the salinity down the river, 
one point of great importance comes to light. It will be seen 
that, while the rise is very slow down to Acle, it becomes 
rapid near this point. Acle must accordingly be regarded 
as marking approximately the upper limit of tidal salt water 
in the Bure. This conclusion is borne out by all other work 
recorded and must be regarded as established. Mr. Robert 
Gurney (this Journal, 1904, p. 638) states, “ For the Bure 
at all events it can be stated that the salt water does not 
normally reach higher than Acle Bridge.” Dr. Otto Hehner, 
giving evidence in the Great Yarmouth Waterworks Case 
says (Minutes of Evidence, House of Lords, 26th June, 1906, 
p. 25), “ About four miles above the mouth of the Bure the 
sea water practically came to a sudden stop. The sea water 
. . . . pushed .... the fresh water in front of it, and 
then it came to an almost abrupt stop. The point where it 
comes to a stop of course would vary with the height of the 
tide, but under the conditions I investigated it was 4 to 5 
miles above the mouth of the Bure. At Stokesby, which is 
12 miles above the mouth of the Bure, I never found more 
than about 2 per cent, of sea water.” 
Mr. Charles Hawksley said (Minutes of Evidence, 26th 
June, 1906, p. 12), “ The salt water enters the Bure and flows 
along it perhaps for 12 miles, not more except under extra- 
ordinary circumstances.” Other estimates place the limit 
at 8 miles up the river (on April 24th, 1906) and 5f miles 
up (ibid., p. 28), but none of them fix it above Acle. 
It follows from the above that the whole of the Bure 
system above Acle is beyond the reach of the tidal salt water. 
Accordingly the presence of salt in the Bure above this point 
or in the Thurne River and the Broads connected with it 
must be attributed to some other source than the direct 
action of the tide at Yarmouth. 
Beyond this limit the only effect of the tide is a secondary 
one, namely the driving back of the waters towards the 
