Mifcellanea Curtofa. 23 



hlgheft. Spring-Tides are not precifely on the New 

 and Full Moons, nor the Neaps on the Quar- 

 ters} but generally they are the third Tides af- 

 ter them, and fometimes later. * 

 All thefe things would regularly come to pafs, 

 if the whole Eaith were cover 'd with Sea very 

 deep j but by reafon of the fhoalnefs. of fome 

 places, and the narrownefs of the Streights, by 

 which the Tides are in many cafes propagated* 

 there a-rifes a great diverfiry in the ErTe£t, and 

 not to be accounted for, without an exa£t Know- 

 ledge of all the Circumftances of the Places, as 

 of the Polition of the Land, and the Breadth and 

 Depth of the Channels by which the Tide flows ; 

 for a very flow and imperceptible Motion of the 

 whole Body of the Water, where it is (for Ex- 

 ample) x Miles deep, will luffice to raife its 

 Surface 10 or Ix Feet in a Tides time, where* 

 as, if the fame quantity of Water were to be 

 convey'd up a Channel of 40 Fathoms deep, 

 it would require a very great Stream to eifeS it, 

 in fb large Inlets as are the Channel of England, 

 and the German Ocean • whence the Tide is 

 found to fet ftrongeft in thofe places where the 

 Sea grows narrower!: ; the fame quantity of Wa- 

 ter being to pafs through a fmaller Paflage : 

 This is moft evident in the Streights, between 

 Portland and Cape de Hague in Normandy, where 

 the Tide runs like a Siuce * and would be yet 

 more between Dover and Calais, if the Tide com- 

 ing about the Ifland from the North did not 

 check it. And this force being once imprefs'd 

 upon the Water, continues to carry it above the 

 level of the ordinary height in the Ocean, par- 

 ticularly where the Water meets a diredt Ob- 

 ftacle, as it is at St. Wlalos\ and where it enters 

 into a long Channel, which running far into 

 C 4 rhf 



