526 REPORT—1890. 
from the middle towards one or other of the sides, cutting away high” 
sandbanks until it followed along the end of the tank into the corner, 
and then flowed back diagonally into the middle. Then, after some 
10,000 tides, a fresh channel would open out suddenly towards the 
middle of the estuary, and then proceed in the same gradual manner 
perhaps to the other side. This happened more than once during the 
progress cf the experiment, which was carried to 85,000 tides. The 
different positions of the channels are apparent in the plans 1, 2, and 3. 
The comparison of these plans and the accompanying sections ‘with 
Plan 1, Experiment V., in the last report shows but slight general effect 
of the land water—so slight, indeed, that it might pass almost unnoticed. 
This shows that the land water does not alter the greatest height of the 
banks or the lowest depth of the channels. 
It will be noticed, however, in the plans that the land water has 
lowered the general level of the sand in the middle of the estuary at the 
top and raised it towards low water. This effect comes out in the mean 
reduced slopes shown in Plate II. From these it appears that the 
effect of the land water, by continually ploughing up the banks at the 
top of the estuary, has been to disturb the previous state of equilibrium, 
lowering the sand near the top and raising it further down the estuary. 
In Experiment VIII., B, the conditions at starting were the same as 
those in 1V., B, and one quart of land water in 2:8 minutes was admitted 
in the same manner as in X., A, the period being 35°4 seconds. The 
quantity of land water per tide was one-fourth the quantity in A, while 
the capacities of the estuaries are as 1 to 8, or the percentage of land 
water in B was 1°8 that of the tidal capacity at starting. After running 
600 tides the rise of tide was increased from 0:094 to 0:097 foot without 
any alteration in the period. The experiment was then continued to 
91,184: tides. 
The apparent effects of the land water observed were exactly the 
same in character as in A, but were decidedly greater on account of the 
larger quantity. The curves agree fairly with those in A. 
26. Hxperiments in short V-shaped Estuaries with and without Land 
Water.—In the tanks A and B inner vertical partitions were introduced 
so as to form the upper end of the tank A into asymmetrical V, of length 
6 feet and greatest breadth 4 feet; while that of tank B was formed in a 
similar manner into a V of length 3 feet and breadth 2 feet. The lengths 
of the tanks were thus unaltered, the tidal capacity being reduced to 
three-quarters of what it was before. ; 
The sand was arranged in a similar manner to that previously adopted, 
except that the initial depth of the sand was 4 inches (0°33 foot in A) 
instead of 3 inches, and the scummers raised so as to maintain the water 
higher in a corresponding degree. 
Heperiments XI, A, and X., B, Plate VIIL., March 18 to-April 29.—In 
Tank A the rise of tide was 176 and the period 47:20. The experiments 
were first started without land water. The observed character of the 
action was much the same as with the rectangular estuaries, being more 
intense towards the top of the V, and quieter at and below the broad 
end. 
The first attempt in Tank B showed that, owing to the diminished 
capacity of the estuaries, the sand would not come down even so well as in 
corresponding experiments with rectangular estuaries. This led to the 
abandonment of Experiment IX., B, and starting X., with a rise of tide 
