76 NATURAL HISTORY oi N RJVAY. 



SECT. IX. 



ft;Tb 0n cur- the My fubject brings me at lafl to the feveral motions of the wa- 

 rents.ebb.and f- er - m Norway, by the ebb and flood, and by other perpetual cur- 

 rents - 3 the motion of the fea by winds, or by the impulfe of the 

 corpufcles of the air, having already in fome meafure been consi- 

 dered in the firft chapter. The motion of the fea is generally 

 from eaffc to weft, tho' it be not always apparently fo to us ; for 

 the earth revolving round its axis with a conftant rapidity, and in 

 an oppofite direction from weft to eaft, and the water as a more 

 lax element, not being capable of equal velocity, but fomewhat 

 flower in its progreflion, the furface thereof feems to be in a con- 

 trary and retrograde motion. The motion of the water is in fome 

 meafure influenced by the fun, but not to fuch a degree here as 

 in the warmer countries ; where its rays being more perpendicu- 

 lar, act with the greater force *, 



Another motion in the fea is interrupted, and mixes with the 

 general ftream, occasioning the water alternately to rife and fall 

 within the twenty-four hours, when the flood proceeds from the 

 eaft, and the ebb from the weft, and thefe alternatives fall out 

 regularly according to the courfe of the moon, fo that they are 

 very little varied by the fhifting of the winds. The greateft height 

 of the flood here is eight feet, but much more ufually from four 

 to fix, which is far fhort of the height in the Netherlands, and 

 Hartf. conj. England,the water being checked in the ftrait betwixt Calais and 

 Difc. i. P . 52. Dover, but having more room to extend itfelf in the north- feaf. 

 That this motion, in other refpe&s one of the greateft myfteries 

 in nature, is, as to its original caufe dependent on the moon, can- 

 not well be controverted : But whence this influence of the cele- 

 dial bodies on the waters of our globe ; whether, according to the 

 fentiment of the ancients, the rays of the moon leave the fea im- 



* The current in fome places is remarkably ftrong and impetuous, as where it 

 is extremely ftraitened and confined at the bottom by ledges of iheers, rocks, or 

 fand-banks, at a fmall diftance from the ihore ; and being thus contracted into a 

 narrow channel, is fo difficult to ftem, that a boat mull either be drawn along by 

 hands on lhore, or wait fome time till the current abates. 



-J- Mr. Lucas Debes, in his defcription of the ifland of Faro, relates fomething, 

 ftrange of a frefhwater-lake near Famoye, a town on a hill of a middling height, 

 that it regularly keeps time with the ebbing and flowing of the fea. As the impref- 

 fion of the moon upon our atmofphere cannot be ftronger on this frefh lake than on 

 others, this muft be fuppofed to have a fubterraneous communication with the fea, 

 through fome vaft and extraordinary hiatus. 



preg- 



