TIDES AND CURRENTS, 32 ?

found to flow strongest in those places that are narrowest,the same quantity of water being, in this case, driventhrough a smaller passage. It is often seen, therefore,rushing through a strait with great force, and considerablyraised, by its rapidity, above that part of the ocean throughwhich it runs.

The shallowness and narrowness of many parts of thesea, give rise also to a peculiarity in the tides of some partsof the world : for, in many places, in our own seas in par-ticular, the greatest swell of the tide is not while the moonis in its meridian height, and directly over the place, butsome time after it has declined thence. The sea, in thiscase, being obstructed, pursues the moon with whatdispatch it can, but does not arrive with all its waters untilafter the moon has ceased to operate. Lastly, from thisshallowness of the sea, and from its being obstructed byshoals and straits, it happens that the Mediterranean, theBaltic, and the Black Sea , have not any sensible tides,to raise or depress them in a considerable degree.

Among the phenomena of the tides, one of the mostsingular is the bore, peculiar to several rivers : it is ascrib-e d to the waters, which were before expansive, beingsuddenly pent up, and confined within a narrow space.This bore, or impetuous rush of waters, accompanies thefirst flowing of the tide in the Perret, in Somersetshire , and* the Seine , in France . It is also one of the peculiarities°f the Severn , the most rapid river in England,

One of the greatest known tides is that of the Bristol Channel , which sometimes flows upwards of forty feet.At the mouth of the river- Indus the water rises thirtyfeet. The tides are also remarkably high on the coasts°f Malay, in the straits of Sunda, in the Red Sea , at the^outh of the river St. Laurence, along the coasts of China a nd Japan , at Panama , and in the gulf of Bengal. The®tost remarkable tides, however, are those at Batsha, in theingdom of Tonquin, in 20° 50' north latitude. In that^ 1 . e sea e bbs and flows once only in twenty-four hours,“fie in all other places there are two tides within that®P a ce. What is still more extraordinary, twice in each month,t'H ° ^ le moon is near the equinoctial, there is not anyWith ^ le water being for some time quite stagnant. These,m other anomalies of the tides there, Sir Isaac Newton *