THE RIVER BURE AND ITS TRIBUTARIES. 
2 3S 
range was 1.6 in., the averages for the three sets of charts 
being i in., 1.5 in., and 2.2 in. These charts show great 
irregularity in the duration of rise and fall. 
Attempts have been made to obtain evidence of a satis- 
factory tide in Hickling Broad and Horsey Mere, but the 
records are so extremely irregular that the attempts were not 
successful. In Horsey Mere there was not the slightest 
oscillation of level, while in Hickling there is an oscillation 
which, if the periodicity of it can be neglected, indicates, 
a rise and fall of about an inch. But there appears to be 
no correspondence between the periods of the oscillation and 
the period of the tidal wave, and it is very probably to be 
interpreted as an irregular rise and fall due partly to the 
pumping of water into the Broad from the marshes and partly 
to wind acting on so large a sheet of shallow water. Such 
a piling up of water by wind is a well-known phenomenon, 
and should be taken account of in all attempts to prove the 
existence of a tide in such waters. 
The evidence of currents in Deep Dike, leading out of 
Hickling Broad, has been adduced to prove the existence of 
a tide, but this evidence is distinctly unreliable. The 
current in this dike varies in direction, sometimes flowing out 
of and sometimes into the Broad, but it has been shown that 
the period of its flow does not correspond with the period of 
a tide. For instance, the evidence given in the Hickling 
Broad Case in 1892, to prove the existence of a tide, showed 
that the period of flow and ebb in the dike varied from i| 
to 21 hours, and also showed that the time of high water was, 
after four days’ observations, i-S hours earlier than on the first 
day, a fact that is obviously not in accordance with tidal 
theories. 
The fact is that, at the limit of tidal influence, that influence 
is so slight that it becomes almost a matter of opinion whether 
it exists or not. With regard to Hickling evidence can be 
adduced that there was no tide in the usual sense at the 
time the observations were made. But it is very possible 
that there are times on which a tide might be distinctly 
traced, but it would certainly require a tide gauge of great 
