39 
in character. More dependence also may be placed upon the pre- 
dicted times as the moon’s distance from the Equator increases. 
Contrary to what might be expected the highest tide and greatest 
range happen when the moon is at its farthest North point, and not 
at its greatest South declination, when the moon would be almost 
directly over Fremantle, and would thus be in a position to exercise 
the maximum attractive force on the water. 
It may be stated, therefore, with some degree of certainty, that 
the Fremantle tides depend to a large extent upon the moon’s 
declination, and from its position the range of tide may be gauged 
fairly accurately, but the irregularity in the occurrence of successive 
highs and lows, although most marked when the moon is on the 
Eqqator, is still to be expected when the moon attains her greatest 
North or South declination. 
On Plates XIII. and XIV. copies of the Fremantle tides for 
June and October, 1910, have been plotted in the same way as the 
Port Hedland curve for June, 1913, shown on Plate XL, so it is not 
necessary to repeat the explanation of the different lines and figures. 
The first thing that strikes the observer is the unevenness of the 
trace compared with that of Port Hedland. The same gradual rise 
and fall of the water level is absent and in addition there is generally 
only one high and one low during the twenty-four hours. This 
affords perhaps the most striking difference between these two tides, 
for whereas the tides of the northern port are almost without excep- 
tion semi-diurnal, namely two highs and two lows every twenty-four 
hours, those of Fremantle are, as just noted, diurnal. The semi- 
diurnal sometimes puts in an appearance but it is only a very half- 
hearted attempt. A close inspection shows that some of the argu- 
ments in favour of the equilibrium theory hold even with these 
tides, but they are not nearly so self-evident. 
It will be noticed that in June, when the tides are diurnal, the 
high water seems to follow the sun by an hour or so, and consequently 
the low tide occurs at night, but this is not invariably the case, for 
a glance at the October trace shows that, when distinct diurnal tides 
take place, the high water occurs at night. 
In order that the effect of the weather upon the tides may be 
appreciated, along the bottom line for each day the barometer read- 
ing and the wind with its velocity are inserted. The north-west and 
west winds, which along the west coast generally spell stormy con- 
ditions, will be found to cause an appreciable uplift of the water 
level; for an example of this notice the abnormal heights of both 
high and low tides from the 5th to the 8th and again on the 26th and 
27th. The same result is apparent in October, especially on the 16th. 
And many of the other points in the main remarks on the Fremantle 
tides may be verified by reference to these charts, but nothing of the 
same convincing nature is brought to light as in the case of the Port 
Hedland tides. 
