orm'd in the same Time; and consequently there must be a like Variation
of the Tides in the Velocity, and in the Risings and Fallings of the Tides,
as to equal spaces of time. And the Tides from New-moon to New-moon being
not alwaies the same in number, as sometimes but 57, sometimes 58, and
sometimes 59, (without any certain order of succession) is another evidence
of the difficulty of reducing this to any great exactness. Yet, because
'tis worth while, to learn as much of it, as may be, the _Proposer_ and
many others do desire, That Observations be constantly made of all these
Particulars for some Months, and, if it may be, years together. And because
such Observations will be the more easily and exactly made, where the Tides
rise highest, it is presumed, that a fit _Apparatus_ being made for the
purpose, they may be made about _Bristol_ or _Cheap-stow_, best of any
places in _England_, because the Tides are said thereabout to rise to ten
or twelve fathoms; as upon the coast of _Britanny_ in _France_, they do to
thirteen and fourteen.

In order to which, this following _Apparatus_ is proposed to be made use
of. In some convenient place upon a Wall, Rock, or Bridge, &c. let there be
an _Observatory_ standing, as neer as may be to the brink of the Sea, or
upon some wall; and if it cannot be well placed just where the Low water
is, there may be a Channel cut from the Low water to the bottom of the
Wall, Rock, &c. The Observatory is to be raised above the High water 18. or
20. foot; and a Pump, of any reasonable dimension, placed perpendicularly
by the Wall, reaching above the High water as high as conveniently may be.
Upon the top of the Pump a Pulley is to be fastned, for letting down into
the Pump a piece of floating wood, which, as the water comes in, may rise
and fall with it. And because the rising and falling of the water amounts
to 60. or 70. foot, the Counterpoise of the weight, that goes into the
Pump, is to hang upon as many Pulleys, as may serve to make it rise & fall
within the space, by which the height of the Pump exceeds the height of the
Water. And because by {300} this means the Counterpoise will rise and fall
slower; and consequently by less proportions, than the weight it self, the
first Pulley may have upon it a Wheele or two, to turn _Indexes_ at any
proportion required, so as to give the minute parts of the motion, and
degrees of risings and fallings. All which is to be observed by
_Pendulum-watches_,