a Cork or a blown Bladder to the Lead, fo as it may be difengaged from it, as foon as the Lead fhall touch the Bottom: this being done, they let down the Lead, and obferve the time between it's touching the Bottom, and the Cork's rifing to the Surface of the Sea; from whence by comparing this with the aforefaid Obfervations, and ftated Pro The Ball B and the Lead B were let down at fixteen Fathoms; and the Ball returned in forty eight fingle Strokes of a Pendulum, held in the Hand, vibrating fifty eight fingle Strokes in a Minute. A fecond time repeated with the fame Succefs; wherefore the Motion was four Foot every Second. Again the Ball A, and the Lead B, whofe Nail was bended into a fharper Angle; the Ball returned in thirty nine Strokes. A fecond time repeated with the fame Succefs, at the fame Depth. Ball A, Lead A, at eight Fathoms and one Foot, returned at twenty; repeated at eight Fathoms, returned at nineteen. Tried the third time at ten Fathoms four Foot, returned at twenty eight. A fourth Tryal at the fame Depth, juft the fame. A fifth, at ten Fathoms five Foot, returned at twenty seven. A fixth Tryal, juft the fame. A feventh at twelve Fathoms five Foot, returned in thirtyseven. An eighth Tryal juft the fame. But if it be alledged, that it must be known, when a light Body afcends from the Bottom of the Water to the Top, in what Proportion of Time it rifes; it may be confidered, that in these Experiments the Times of the Defcent and Ascent are both taken and computed together; fo that for this Purpofe, there needs not the Nicety which is alledged. portions, But portions, they find the Depth of the Ocean. there is fuch a Nicety required in making thefe Tryals, and the time of Obfervation is fo fhort, that it is very rare to find the true Depth by this Method. However it appeareth, that the Depth of the Ocean is every where finite, and not extended to the Antipodes; becaufe if two Portions of Earth were divided by any Part of the Ocean, which might be continued thro' the Center to the oppofite Side of the Globe, unless they were fupported with Arches, they would immediately fall together at the Center, because the Earth is heavier than the Water. Befides, the whole Bulk of Earth and Water is finite and spherical; and therefore the Depth of the Ocean cannot be infinite. MOREOVER, from the Obfervations of the Depth in divers Places, it is manifeft, that the Chanels in Depth are nearly equal to the Mountains and inland Parts in Elevation, that is, as much as the one is raised, fo much the other is depreffed, and as the Altitude of the inland Parts is gradually increased from the Shore, fo is the Sea deeper and deeper towards the Middle of the Ocean, where the Depth is for the moft part greatest. THE Depth of the Sea, is in the fame Place often altered by thefe or the like Caufes. 1. By the Flux and Reflux. 2. by the Increase and Decrease of the Moon. 3. By the Winds. 4. By the mouldering and fubfiding of the Shores; whence the Chanel is made higher in process of time by Sand and Mud. PROPOSITION VII. The Ocean doth not flow from Springs, but is contained within the Cavities of the Earth; tho' it is not always numerically the fame, but continually increafing and diminishing. WE WE know by Experience that the Water of Rivers is produced by Springs, and because it hath been fo for many Ages paft, it neceffarily follows, that the Water which is continually flowing to the Sea, returns again to the Fountains, either by fubterraneous Ducts, or fome other way. The Philofophers of old were alfo of Opinion, that the Sea iffued forth at several Springs; neither could the Magnitude nor the Perpetuity of it's Bulk convince them of their Error, for they said, that it was conveyed by fubterraneous Fiffures to these Fountains, which therefore kept continually flowing. Aristotle (Book ii. Meteor. Chap. ii.) endeavours to prove the contrary, and to refute the Arguments of the Ancients, but fays very little to the Purpofe; we think these following will be more effectual to difprove them. If the Ocean have Springs they must either be in the raised Parts of the Earth, or in that Part which is covered with the Ocean, that is in the very Chanel of the Sea. That there are no fuch upon the dry Land is apparent, because there were never yet found any; and to say that they are in the unknown Countries towards the North or South Pole is to take a Thing for granted without any manner of Reafon for it, because most of thefe Countries are covered with Ice continually, and as many as are discovered of them afford no Springs at all. Neither can they pretend to fay that they are in the Chanel of the Sea; for if they were, they would be no further diftant from the Center than the Ocean itfelf; and therefore the Water in them would not flow, but be at Reft, because it is against Nature that it fhould ascend from a lower to a higher Place; and the Springs of all Rivers are higher than the Waters they emit. Some indeed may object that this Motion is violent, because that the Bottom of the Ocean, being perforated into Ducts, Meanders, Fiffures, or Ca nals, nals, (which you'll please to call them) is not terminated in the Earth's Bowels, but extended to another Part of the Bottom of the Ocean by more Intercourses than one; fome of which convey the Water one way, and fome another, fo that it iffueth out of each, as if they were fo many Springs. And fince (fay they) it is not contrary to Reason to fuppofe many of thefe Paffages or Intercourses, nothing hinders but that there may be alfo as many Springs in the very Chanel of the Ocean. But thefe are all vain Fancies, and no way agreeing with the Nature of Water; for tho' the Water be continued thro' these Orifices, it will not flow thro one or the other, but be at Reft, unless it be urged by fome external Caufe; and tho' it be preffed by the incumbent Water on this fide the Intercourse, it will not discharge itself at the other; because it is as much preffed by the incumbent Water there, which keeps it in Equilibrio, and at Reft, as may be proved by Experiment thus: Let ABCD (Fig. 20.) be a Veffel full of Water, and A B it's fpherical Superficies. Let RPEF be a hollow Beam of Wood, lying obliquely under Water, fo that the whole at g under A may be higher than the Hole at b under B. Then the Water will flow in at both ends of the Beam 'till the hollow Part be full; but there will be no Flux at either Orifice; not at g because it is higher nor at b, because, tho' it be lower than g, yet the greater Weight of the Water about B will stop the Flux (e). (e) For, by the Laws of Hydroftatics, the Weight of the greater Column of Water under B is of the fame force to prefs the Water upwards at the Hole b, as the leffer Column of Water under A, and it's own relative Gravity in the declining Bore is to press it downwards at the Hole gi therefore it remains in Equilibrio, and at Reft. IF it should be again objected, that the incumbent Water upon the one Orifice is of a less Altitude, and therefore not of fo great Force to repel the Flux of Water, which is immitted at the other: We anfwer, 1. That such a thing may be, if the Superficies of the Water, which preffeth one Orifice, be feparated or not continuous to the Superficies of the Water that preffeth the other Orifice; but if thefe two Surfaces are continuous, the Water will fooner descend by that Continuation to the lower Place, than by this fubterraneous Duct. 2. If what was objected be allowed, this Motion would in a fhort time cease, viz. when fo much Water was run out by the Intercourse from the higher to the lower Place, as to make both their Surfaces of an equal Altitude. And further, fuppofe one part of the Ocean was perpetually higher than the other, there could be no Reafon given, why the Water fhould circulate, or interchangeably be poured from one Part into another. FROM whence it is evident, that the Ocean hath no Springs, but is a vaft Collection of Waters contained in Chanels. YET there are fome things to be taken no-, tice of, which are commonly objected against this, viz. 1. THAT our proof is built upon a Suppofition, that the Ocean, as to it's natural Conftitution, is continually at Reft, without taking notice of it's being moved by any external Caufes: but there is no time in which the Ocean is not in Motion, either by the Wind or Tide, or fome other violent Agent, which causes the Altitude and quantity of the Water to be greater fometimes in one Place and fometimes in another; and then the Water which is more elevated, is poured into thofe fubterraneous Intercourses, and rushes towards the Parts that are of a lefs Altitude, and where the incumbent Water is lefs |