Chapter 5, page 4
5.4 5.1 The action by the Moon and the Sun.
5.2 The physical equation valid for the ocean tides.
5.3 The space unit of an ocean tide.
5.4 The tide wave cadence.
5.5 The time taken by a tide wave.
5.6 The direction of the action.
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This point has been already treated on 4.10.
#06 - The tide wave cadence.
.1 A tide wave takes place within a basin. Its cycle may have either a diurnal cadence (seldom), or, a semi-diurnal one (most commonly).
Example of a semi-diurnal tide basin.
In the eastern basin of the North Atlantic, where tides occur twice a day, the cotidal lines (in red) show the average delay given in hours of the first tide after the passage of the moon on the meridian, as well the average delay of the second tide after the passage of the moon above the opposite meridian.
.2 In a tide basin, where the tide cadence is semi-diurnal, the tide wave takes, on average, 12 hours and 25 minutes to go round completely.
.3 While, in a tide basin, where the cadence is diurnal, it takes 24 hours and 50 minutes.
.4 Moreover, there are other less common tide patterns.
Constraint #4.
.5 From this fact, I infer that the force which brings about the tides should have another feature: that it could generate a tide, either with a cadence of one per day, or with a cadence of two.
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