And whereas 'tis obferved , that upon the main Sea fiiore the Current of 
the Bbbings and Flowings is fometiracs fwifcer, and fonaetimes flacker , than 
at others , fo as in the beginning of the Flood the Tide moves fafler but in a 
fmall degree , increafing its fwiftnefs condantly rill rowaisds the MMie of the 
Floud V and then decreafingin velocity again from the Middle till to the top 
of the High- water ; it is fuppofed, that in Equal fpaces of Time,th6 Increafe 
and Decreafe of velocity , and confequently the degrees of the Rifings and 
Fallings of the fame^in Equal fpaces of tinse , are j^rformcd according to the 
fro^Qrtion of Sinss, 
But 'tis withali conceived, that the faid Pr&portion cannot hold exAElly and 
frecifely^ in regard of the iHe^mlitus, that fall out in the Periods of the Tides^ 
which arc commonly obferved and believed to follow certain of the 
Moon in regard of tl}e Equinox , which are known not to keep a precifg znd 
gonfiant Courfe i fo iihat, there not intervening equal portions of Time be« 
twecn one New Moon^nd another, the Moons return to the fame Meridian^ 
cannot bealwaies performed in the fame Time and confequently there muft 
fee a like Variation of the Tides in the Velocity , and in the R ifings and Fai- 
lings of the Tides , as to equal fpaces of time. And the Tides from New- 
moon to New-moon being not alwaies the fame in number , as fometimes but: 
57, fometimes 5 8 ,and fometimes 59 , ( without any certain order of fuccef- 
lion) is another evidence of the difficulty of reducing this to any great ex- 
aftncfs. Yet, becaufe *tis Worth while, to learn as much of it, as n=iay be, the 
Frepofer and many others do defire , That Obfervations be conflancly made 
of all thcfc Particulars for fomc Month8,and, if it may be^ years together. And 
becaufe fuch Obfervations will be the mor^ eafily and cxadly made , where 
the Tides rife higheft,it is prcfumed, that a fit AppdrAtus being m^de for the 
purpofe,they may be made about Brifld or Cheap- ^ow , beft of any places 
in ^wf/W, becaufe the Tides are faid thereabout to rife to tenor twelve 
fathoms^ asupon thecoaftof ^n>^»^; in /r^urf ^ they do to thirteen and 
fourteen* 
In order to which, this following Apparstsis is propofed to be made ufe of. 
In fome convenient place upon a Walt, Rock, or Bridge, &c. let there be an 
Ohfervntorj (landing, as neer as may be to the brink of the Sea, or ijpon fom.e 
wall • and if it cannot be well placed juft where the Low water is, there may 
feea Channel cut from the Low water to the bottom of the Wall, Rock, &c; 
The Gbfervs^tory is to be raifed above the High- water 1 8. ©r 20. foot ; and 
a pump,of any reafonable dimcnfion, placed perpendicularly by the Wail , 
reaching above the High- water as high as conveniently may be. Upon the 
tap of the Pump a Pulley is to be faftned, for letting down into the Pump a 
piece of floating wood, which, as the water comes in,may rife and fall with it. 
And becaufe the rifing and falling of the water amounts to 6©. or 70. foot, 
the Counterpoife of the weight , that goes into the Pomp , is to bang upon 
as many Pulleys, as may ferve to make it rife & fall within the fp^ce,by which 
the height of the Pomp exceeds the height of the Water, And becaufe by 
