364. Sir I S A A C N E W T O N’s Book IV.

hours to come from the ocean to London-bridge , so that, whenit is high water there, a new tide is already come to its heightin the ocean ; and, in some intermediate place, it must be lowwater at the same time. In channels, therefore, and narrowseas, the progress of the tides may be, in some respects, com-pared to the motion of the waves of the sea. Our author alsoobserves, that when the tide runs over Ihoals, and flows uponflat shores, the water is raised to a greater height than in theopen and deep oceans that have steep banks; because the forceos its motion cannot be broke, upon these level shores, till thewater rises to a greater height. 1

...Is a place communicates with two oceans, (or two differentways with the same ocean, one of which is a readier and easierpaffage) two tides may arrive at that place in different times,which, interfering with each other, may produce a great varietyof phænomena. An extraordinay instance of this kind ismentioned by our author at Batjha , a port in the kingdom of'Tunquin in the East Indies , of northern latitude 20° 50'. Theday in which the moon pastes the equator, the water stagnatesthere without any motion : as the. moon removes from theequator, 1 the water begins to rife and fall once a day ; and it ishigh water at the setting os the moon, and low water at herrising. This daily tide increases for about seven or eight days,and then decreases for as many days by the same degrees, tillthis motion ceases when the moon has returned to the equator.When she has passed the equator, and declines towards the southpole, the water rises and falls*again, as before ; but ’tis highwater now at the rising, and low water at the setting, os themoon.

Our author, to account for this extraordinary tide, considersthat there are two inlets to this port of Batfha r one from the

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