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Sect. III.] 



HYDROGRAPHY. 



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V 



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'* 



V* '.R* 



«♦ 



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the tide-pole during and after the 'shock, and if any un 



U. Xi 



dulations of the water are observed, note them, and the 



they pr( 

 '^er to pi 







h 



guard 



$- 



a bar, sand-bank, or any such impediment to the free 



action of the water. 



The Bore 



nomenon, the bore, a wave w^hich 



place 



ph 



he 



? 



threatening destruction to boats and 



even to shipping ; note the time of the tide at which it 



and rushing onward 



begins, 



there be one tmve only or more, the 



fbTSt 



with 

 and 



and 



below the spot- The 



tides ; note 

 correct.* 



cularly whether this observation be 



Freshes. 



26, Connected with the rise and fall of the water is that 

 periodical elevation of the surface of rivers by "freshes,'* 

 occasioned by heavy and continued rains in the interior of 



the countrv- 



.nly 



here 



level of the river ^ properly so called ; but " 



♦ The reraark made in '' How to observe [p. 35] that either rocks or 

 shoals, or great depth of water secure a river from the inconvenience 

 of the bore," is not always correct; for the Severn is encumbered with 

 shoals, and has a bore which has proved destructive to vessels grounded 

 upon ^he sands. 



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