of which is (as hath often been &longs;aid) the determinate accelera <lb/>
tion and retardation of the parts of the Earth, from whence <lb/>
the Waters have a determinate period put to their decur&longs;ions <lb/>
towards the Ea&longs;t, and return towards the We&longs;t, in the time of <lb/>
twenty &longs;our hours. </s><s>The other is that which dependeth on the pro <lb/>
per gravity of the Water, which being once commoved by the <lb/>
primary cau&longs;e, &longs;eeketh, in the next place, to reduce it &longs;elf to <emph type="italics"/>Æ <lb/>
quilibrium,<emph.end type="italics"/> with iterated reciprocations; which are not deter <lb/>
mined by one &longs;ole and prefixed time; but have as many varie <lb/>
ties of times as are the different lengths and profundities of the <lb/>
receptacles, and Straights of Seas; and by what dependeth on <lb/>
this &longs;econd principle, they would ebbe. </s><s>and flow, &longs;ome in one <lb/>
hour, others in two, in four, in &longs;ix, in eight, in ten, &c. </s><s>Now if <lb/>
we begin to put together the fir&longs;t cau&longs;e, which hath its &longs;et Period <lb/>
from twelve hours to twelve hours, with &longs;ome one of the &longs;econ <lb/>
dary, that hath its Period <emph type="italics"/>verb. </s><s>grat.<emph.end type="italics"/> from five hours to five <lb/>
hours, it would come to pa&longs;&longs;e, that at &longs;ometimes the primary <lb/>
cau&longs;e and &longs;econdary would accord to make impul&longs;es both one <lb/>
and the &longs;ame way; and in this concurrency, and (as one may call <lb/>
it) unanimous con&longs;piration the flowings &longs;hall be great. </s><s>At other <lb/>
times it happening that the primary impul&longs;e doth, in a certain <lb/>
manner, oppo&longs;e that which the &longs;econdary Period would make, <lb/>
and in this conte&longs;t one of the Principles being taken away, that <lb/>
which the other would give, will weaken the commotion of the <lb/>
Waters, and the Sea will return to a very tranquil State, and <lb/>
almo&longs;t immoveable. </s><s>And at other times, according as the two <lb/>
afore&longs;aid Principles &longs;hall neither altogether conte&longs;t, nor altoge <lb/>
ther concur, there &longs;hall be other kinds of alterations made in <lb/>
the increa&longs;e and diminution of the ebbing and flowing. </s><s>It may <lb/>
likewi&longs;e fall out that two Seas, con&longs;iderably great and which <lb/>
communicate by &longs;ome narrow Channel, may chance to have, by <lb/>
rea&longs;on of the mixtion of the two Principles of motion, one <lb/>
cau&longs;e to flow at the time that the other hath cau&longs;e to move a <lb/>
contrary way; in which ca&longs;e in the Channel, whereby they di&longs; <lb/>
imbogue them&longs;elves into each other, there do extraordinary <lb/>
conturbations in&longs;ue, with oppo&longs;ite and vortick motions, and <lb/>
mo&longs;t dangerous boilings and breakings, as frequent relations <lb/>
and experiences do a&longs;&longs;ure us. </s><s>From &longs;uch like di&longs;cordant moti <lb/>
ons, dependent not onely on the differenr po&longs;itions and longi <lb/>
tudes, but very much al&longs;o upon the different profundities of the <lb/>
Seas, which have the &longs;aid intercour&longs;e there do happen at &longs;ome <lb/>
times different commotions in the Waters, irregular, and that <lb/>
can be reduced to no rules of ob&longs;ervation, the rea&longs;ons of which <lb/>
have much troubled, and alwayes do trouble Mariners, for that <lb/>
they meet with them without &longs;eeing either impul&longs;e of winds, or