And whereas *tis obferved , that upon the main Sea* fhore the Current of 
the Ebbings and Flowings is fometimes fwifter, and sometimes flacker , than 
at others , fo a§ in the beginning of the Floud the Tide moves fafter but in a 
fmatl degree jincreafing its fwiftnefs conftantly dll towards the Middle of the 
Floud •, and then decreafmg in velocity again from th eMiddle till to the top 
of the High-water • it is fuppofed, that in Equal fpaces of Time,the Increafe 
■and Decreafe of velocity , and confequently the degrees of the Rifings and 
Fallings of the fame, in Equal fpaces of time , are performed according to the 
Proportion of Sines. 
But 'tis withal! conceived, that the faid Proportion c annot hold exaBly and 
precisely , in regard of the Inequalities, that fall out in the Periods of the Tides, 
which are commonly obferved and believed to follow certain Portions of the 
Moon in regard of the Equinox , which are known not to keep a preci/e and 
eonftant Courfe : fo that, there not intervening equal portions of Time be- 
tween one New- Moon and another, the Moons return to the fame Meridian , 
: cannot bealwaies perform'd in the fame Time ; apd confequently there mu ft 
fee a like Variation of the Tides in the Velocity , and in the Rifings and Fal- 
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- 
fion) is another evidence of the difficulty of reducing this to any great ex- 
a&nefs. Yet, becaufe ’tis worth while, to learn as much of it, as may be, the 
i Prepofer and many others do defire , That Obfervations beconflantly made 
t of all thefe Particulars for fame Months,and, if it may be, years together. And 
becaufe fuch Obfervations will be the more eafily and exa&ly made , where 
the Tides rife higheft,it is prefumed, that a lit Apparatus being made for the 
purpofe,they may fee made about Brifid or Cheap- [low „ beft of any places 
in England, becaufe the Tides are faid thereabout to rife to ten or twelve 
fathoms ^ as upon thecoaftof Britamy in France , they do to thirteen and 
fourteen* 
In order to which, this following Apparatus is propofed to be made ufe of. 
In fome convenient place upon a Wall, Rock, or Bridge, &c let there be ait 
Ohfervatory Banding, as neer as may be to the brink of the Sea, or upon fome 
wall ; arid if it cannot be well placed juft where the Low water is, there may 
fee a Channel cut from the Low water to the bottom of the Wall Rock See 
Ike Obfervatory is to be raifed above the High-water 18. or 20/foot ; ’and 
a pump,of any reafonable dimenfion, placed perpendicularly by the Vail 
reaching above the High-water as high as conveniently may be. Upon the 
top 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 60, or 70 foot 9 
ithe Counterpoife of the weight , that goes into the Pump , is* to ban 0 upon 
as many Pulleys, as may ferve to make it rife & fall within the fpace,by which 
me height of the Pump exceeds the height of the Water. And becaufe by 
this 
