THE RIVER BURE AND ITS TRIBUTARIES. 2\J 
machine somewhat similar to an ordinary barograph. The 
rise and the fall of water are communicated, by means of a 
float and counterpoise, to the instrument, and the movement 
is recorded as a curve traced on a chart (see Fig. i). The 
drum revolves once in 24 hours, so that each chart records 
the tides of a single day. The instrument has been carried 
about the river on the Wherry “ Cyclops,” and set up wherever 
required, and occasionally two identical instruments have 
been set up simultaneously in different spots for comparison. 
The instrument is an exceedingly convenient and accurate 
one. The only difficulty experienced with it is that it is 
impossible to find in the river places where the float is com- 
pletely sheltered from waves. The waves made by passing 
boats are sometimes so violent as to jerk the float wire off 
the wheel of the gauge, so that constant watchfulness is 
necessary during the day time. I have also known a mis- 
chievous person deliberately to interfere with an unattended 
machine. 
Much use has been made of the records of the tides kept 
for many years at Yarmouth, and I wish to express my 
hearty thanks to the Yarmouth Port and Haven Commissioners 
for their courtesy in granting me permission to make copies 
of their records, and to the Harbour Master, Captain 
Bammant, for the facilities he has granted me in doing so. 
River Tides. 
It is important at the outset to state what may properly 
be understood by the word Tide. The word is very freely 
used upon our rivers, and appears to be applied generally to 
any and every movement of the water, periodic or otherwise. 
The tide in a river shows itself firstly by a rise and fall of 
the water level, and secondly by an ebb and flow of water. 
The first is the tidal wave as propagated from the sea and 
corresponds to it more or less nearly in period. The second 
is the tidal stream which is only a secondary effect of the tidal 
wave caused by the entry of it into shallow water. This 
