. 
ON THE ACTION OF WAVES AND CURRENTS. 527 
0110, without, however, altering the level of the sand. The experiments 
were continued in both tanks without land water until about 40,000 tides 
had been run, and Plans 1 and 2 had been taken. These plans show the 
similarity of the effects in the two tanks. They also show decidedly the 
character of the distribution of the sand in the V-shaped estuary. It will 
be seen that the extreme positions of the contours up the estuary are 
much the same as in the rectangular estuaries, while the extreme posi- 
tions down the estuaries are very much increased. The low-water contours 
extends from Section 11 to Section 19, while in Experiment V., A, Plan 1, 
it extend from Section 11 to Section 18. The low-water channels are 
nearly the same depth at corresponding points all down the estuary in 
both experiments, while in the V estuaries the banks extend 6 to 7 
miles (reduced to a 30-foot tide) further down, 
. After Experiment XI., A, and X., B, had proceeded to about 40,000 
tides, corresponding quantities of land water were introduced at the tops 
of the estuaries, one quart in one minute in A, about 1 in 140 the tidal 
capacity ; in B one quart in 5°68 minutes, or about 1 in 140 the tidal capa- 
city. The tanks were then run on for 12,000 tides, and surveys for the 
plans 3 made. The general effect of this land water, as shown in these 
experiments, is, as before, to lower the sand at the tops of the estuaries 
and slightly to raise it at the bottom. They were not, however, continued 
long enough to show a state of equilibrium. As in the rectangular 
estuaries, the detailed effects of the land water were much more observ- 
able than those shown in the surveys. The land water continually 
ploughed up the sand at the top of the estuary and kept the banks down, 
but owing to the narrowness of the estuary the general effects of this were 
not so striking as in the rectangular estuaries. 
Hzperiments XII., A, and XII., B, with Land Water, Plate X., April 29 to 
May 19.—These were under conditions precisely similar to XI., A, and X., 
B; XI., B, with land water, was started, but owing to an accident it was 
re-started as XII., B. 
Both experiments were run about 16,000 tides and then surveyed, and 
then run on about 16,000 more tides and surveyed again. 
The plans are all very similar, and show but little difference from the 
plans 3 with land water in the previous experiments. 
27. Experiments in long V-shaped Hstuaries without and with Land 
Water in Tanks C and D.—Tank C was formed by extending A by adding 
a rectangular trough to the top, and so as to admit of partitions forming 
a V extending from Section 23 (12 A), and D was formed by extending 
Bin a similar manner. The lengths of the tanks were thus extended 
6 feet and 3 feet greater than A and B, while the capacities were the 
same as the original capacity of A and B. 
The sand in C (A extended) was laid 4 inches deep from the top of 
the V to Section -28°5 C (17°5 A). 
The sand in D (B extended) was laid 2} inches deep from the top of 
the V to Section 28°5 D (17°5 B). 
Experiments I., C and D, Plate XI., May 24 to June 16, without Land 
Water.—In C the tide was 0°162 foot., and the scummer was placed so that 
the mean tide when running was 0:008 foot above the initial level of the 
sand ; this was not observed at the time, being a consequence of the land 
water raising the level of low water by the necessity of getting over the 
weir. 
In D the tide was 0°105 foot and the mean tide was ‘010 foot below 
