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them rather to dry up, thro' a long want of Rain, than to become brackish, or be turned into falt.

THEREFORE, rejecting these falfe Opinions concerning the Origin of Salt in the Ocean, let us lay hold of fome others that seem more probable (ƒ).

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have obferved (fays he) that all the Lakes in the World, properly fo called, are found to be falt, fome more fome lefs than the Ocean Sea, which, in the present Cafe, may also be esteemed a Lake; fince by that Term I mean fuch ftanding Waters as perpetually receive Rivers running into them, and have no Exit or Evacuation.

The number of thefe Lakes, in the known Part of the World, is exceeding small, • and indeed, upon enquiry, I

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1. THESE

Ocean. The Lacus Afphal'tites is fo exceeding falt, that it's Waters feem fully fated, or fcarce capable to diffolve any more; whence, in Summer time, it's Banks are incruftated with great Quantities of dry Salt, of fome'what a more pungent Nature than the Marine, as having a relifh of Sal Ammoniac; as 'I was informed by a curious • Gentleman that was upon the Place.

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• The Lake of Mexico, pro

perly speaking, is two Lakes divided by the Caufways that lead to the City, which is built in Iflands in the midst of the Lake, undoubtedly for cannot be certain there are in it's Security; after the Idea, all any more than four or five, it is poflible, it's first Founders viz. 1. The Cafpian Sea. 2. borrowed from their Beavers, The Mare Mortuum, or Lacus who build their Houses Afpbaltites. 3. The Lake on in Damms they make in the which ftands the City of Rivers after that manner. Mexico; and 4. Titicaca a Now that part of the Lake Lake in Peru, which, by a which is to the northwards • Chanel of about fifty Leagues, ⚫ of the Town and Caufways, • communicates with a fifth and ✦ receives a River of a considerfmaller, called the Lake of able Magnitude, which being Paria, neither of which have fomewhat higher than the o⚫ any other Exit. Of these the ther, does with a small fall Cafpian, which is by much ' exonerate itfelf into the fouththe greateft, is reported to beern Part which is lower. ⚫ fomewhat lefs falt than the Of these the lower is found

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1. THESE Particles are coëval with the Ocean itself, and therefore it is the fame thing to enquire about the Origin of the terraqueous Globe, and the Fabric of the whole World, as to dif pute how the Ocean came to be falt.

2. IF this Opinion do not please, we will propofe another, viz. that these Particles were, in times paft, washed and disjoined from the Earth, and diffolved in the Water; for we need not doubt but that there are feveral Mountains and Rocks of Salt in the Chanel of the Sea. The Island of Ormus is nothing but white hard Salt, of which they make the Walls of their Houses, and there

to be falt, but to what Degree I cannot yet learn; though the upper be almoft • fresh.

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And the Lake of Titicaca, being near eighty Leagues in Circumference, and receiving

• feveral confiderable fresh Rivers, has it's Waters, by the Teftimony of Herrera and Acofta, fo brackish as not to be potable, tho' not fully fo falt as that of the Ocean; and the like they affirm of ⚫ that of Paria, into which the Lake of Titicaca does in part exonerate itself, and which I doubt not will be found • much falter than it, if it were enquired into.

Now I conceive, that as all the Lakes mentioned do receive Rivers, and have no • Exit or Discharge, fo 'twill ⚫ be neceffary that their Waters

rife until fuch time as their • Surfaces are fufficiently extended, fo as to exhale in • Vapour that Water that is poured in by the Rivers; and

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'confequently that Lakes muft be bigger or leffer according to the Quantity of the fresh Water they receive. But the Vapours thus exhaled are perfectly fresh, fo that the faline Particles that are brought in by the Rivers remain behind, whilft the fresh evaporates; and hence 'tis evident, that the Salt in the Lakes will be continually augmented, and the Water grow falter and falter. But in Lakes that have an Exit, as the Lake of Gennefaret, otherwise called that of Tiberias, and the upper Lake of Mexico, and indeed in most others, the Water being continually running off, is fupplied by new fresh RiverWater, in which the faline Particles are fo few as by no means to be perceived.

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Now if this be the true Reason of the Saltness of thefe Lakes, 'tis not improbable but that the Ocean itself is become falt from the fame • Cause, &c.

is not one Spring of fresh Water in the whole Inland. There are alfo feveral Mines of Salt in the Earth, as every one knows, fome of which we have defcribed in Chapter xi. But there is no need of particular Examples; let us confider the whole Earth, and we shall find a great Part of it to be nothing but Salt; it's Coherence and Compofition is by Salt, and, as Chymifts and Natural Philofophers rightly obferve, all folid Bodies are concreted and joined by Salt; which Experience alfo proves; for if any hard Body be burned and confumed to Ashes, much Salt will be found in it.

NOTHING can be alledged against this Opinion of any Weight, and which may not be eafily refuted. Some have thought it impoffible that thefe falt Particles of the Earth fhould perpetually fuffice, and should not at fome time be quite washed away by the Water of the Ocean, which conftantly takes away fome Part of them: To which we anfwer; that the Salt, thus wrought upon, is not fo much leffened as to need great recruiting; and if any be disjoined, or fhaken from the reft, it is not carried without the Ocean, but laid up in fome other Place.

PROPOSITION IX.

Whether the Sea-Water be fresher nearer the Bottom? and why, in fome Places, freb Water is drawn from the Bottom of the Ocean?

TO thefe Questions I anfwer; That we have not found it fresher near the Bottom, except in fome particular Places; where, it is very probable, there are Springs of fresh Water. For it is against Nature that Salt Water fhould float above fresh, when it is heavier.

THOSE

THOSE Places of the Sea where there feem to be fresh Water Springs, at the Bottom, the Studious may collect out of Geographical Authors (ƒ)..

PROPOSITION X.

The Water of the Ocean is lefs falt by how much it is nearer the Poles, and falteft about the Equator, or in the Torrid Zone.

THIS is only to be understood of moft Parts of the Ocean, for the Propofition admits of fome few Exceptions.

THERE are feveral Reafons for this unequal Saltnefs, viz.

1. THAT the Heat of the Sun in the Torrid Zone exhales more Vapours than in the northern Countries, and thefe Vapours are all fresh Water for the Particles of Salt are not fo easily evaporated by reafon of their Gravity; and therefore the

(f) That the Curious may not be at a Lofs to examine the Saltnefs of the Water at feveral Depths, Dr Hook invented an Inftrument to fetch it up at any Depth, which is described in Philof. Tranf. No 9. Page 149. and No 24. Page 447. or in Lowthorp's Abridgment, Vol. 2. Page 260. Thus :

Let there be made a fquare wooden Bucket C, (Fig. 21.) whofe Bottoms EE, are fo contrived, that as the Weight A finks the Iron B, to which the Bucket C, is faftened by two Handles DD, on the end of which are the moveable Valves or Bottoms EE, and thereby draws down the Bucket; the

Refiftance of the Water keeps up the Bucket in the Pofture C, whereby the Water hath, all the while it is defcending, a clear Paffage through; whereas, as foon as the Bucket is pulled upwards by the Line F, the Refiftance of the Water to that Motion, beats the Bucket downwards, and keeps it in the Pofture G, whereby the included Water is kept from getting out, and the ambient Water kept from getting in.

By the advantage of this Veffel, you may know the Conftitution of the Sea-Water in feveral Depths; and whether it be falter at, and towards, the Bottom.

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SECT. IV. Water that is left in the Ocean ought to be more falt about the Equator than towards the Poles, where there is not fo much fresh Water exhaled because of the wak Heat of the Sun.

2. A fecond Caufe is the Heat and Coldness of the Water; for the fame Water, falt Meat, pickled Beef, Pork, &c. tafte falter when hot than when cold, as every one knows from his own Observation because the Heat, or the Particles of Fire, agitate and sharpen the Particles of Salt contained in fuch Meat, and feparate them one from another; fo that they ftrike and prick the Tongue more sharply. Therefore, because the Sea-Water, near the Equator is hotter, and coldeft towards the Poles, it follows, that tho' every Part of the Ocean were admitted to be of equal Saltnefs, yet it ought to tafte falteft about the Equator, and freshest near the Poles.

3. A third Caufe is a greater or lefs quantity of Salt in divers Parts of the Chanel of the Sea; for as we find not Mines of Salt all over the dry Land, nor a like quantity of Salt in the Places where they are found, the fame may be fuppofed at the Bottom of the Ocean, where fome Shores and Chanels are not fo full of Salt as others. Therefore where there is a greater quantity of Salt at the Bottom of the Ocean, there the SeaWater is more falt, because there is greater Plenty of this Mineral imbodied or soaked in it, as is eafy to conceive. For this Reason the SeaWater near the Isle of Ormus is extream falt, because the Ifland itself is all Salt. But whether there be a greater quantity of Salt Mines under Water in the Torrid Zone than about the Poles is uncertain for want of Observations; but fome think it probable (because of the greater Heat of the Sun whereby the fresh Particles are exhaled)

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