PROPOSITION VIII.

To determine whether the Cafpian Sea be a Lake or a Bay of the Ocean.

SOME will have it to be properly called a Sea;: as a Sea, properly speaking, is an extended Part of the Ocean, or is joined to it by a continued Tract of Waters. But they will have it to be joined to the Ocean by fome fubterraneous Intercourfe. Some indeed of the Antients wrote, that it was joined by an open Streight, to the Indian Ocean; others, to the northern Ocean; but both were deceived, as we are well affured by Experience. Whether there be fubterraneous Intercourfes we do not know; only there feem to be fuch, because so many and fo large Rivers exonerate themselves into it, and are constantly pouring in their Waters, where, by, in process of Time, the Chanel would be filled and run over, unless there were fubterraneous Fiffures and Meatus's, thro' which it might evacuate it's fuperfluous Waters into the Ocean (b). But others think thefe Waters are diftributed among the adjacent Mountains, and fupply them with that vaft number of Springs which is obferved hereabouts. Scaliger and others were of Opinion, that this Cafpian Sea runs under Ground into the Euxine Sea, but he gives no Reafon for it; this may be faid, that the Euxine Sea is continually difgorging a large quantity of Water thro' the Bosphorus, and fome think this is more Water than the Rivers pour into it; therefore it may perhaps receive it

(6) By what means the Caf pian Sea (and all others) lofe as much Water daily, as they receive from the many Rivers

flowing into it; is difcuffed in the Note (k) upon Prop. xiv Chap. xiii. which fee.

from

from the Caspian Sea. It feems to me to have no Communication any way with the Ocean, and therefore ought rather to be called a Lake, than a Sea. How it came at firft is another Question. Some avouch that there are found feveral Mountains of Salt in the Bottom, whereby it hath acquired fuch a Degree of Saltnefs; and that it is replenished by the many Rivers that exonerate themfelves into it. But it feems more feasible, (tho' thefe Rivers may contribute to it's Repletion) that this Sea hath, a great many Ages ago, been joined to the Ocean, and that it's Streights, by fome means or other, were filled up and stopped, perhaps by interjacent Islands which gained upon the Shores, in a manner which we shall explain hereafter. And very likely, by the fame Cause, the Euxine Sea may, fome time or other, become a Lake, the Bofphorus being filled up or obftructed.

PROPOSITION IX.

To make a Lake in any Place, if it be poffible.

THIS may be done if there be a River near, or a Spring upon the Place, and if the Place itself be depreffed; tho' fmall Lakes may be made upon the very tops of the Mountains. First the Place is to be hallowed, and dug to fuch a Depth and Extent as we defire, and the Sides are to be fortify'd with Wood-Work, if we fee occafion. Then a Chanel is to be made, by which the River is to be let in; but if there be a Spring upon the fpot, there is no occafion for fuch a Chanel,

:

PROPOSITION X.

To drain a Lake.

THIS may be done two Ways; 1. If the bottom of the Lake be a little higher, or almost of the fame Altitude with the adjacent Places, dig a Chanel, and let out the Water; and by throwing in Heaps of Earth, together with the Heat of the Sun, it will in a fhort time be left dry.

2. IF the bottom of the Lake be lower than the adjacent Ground, it is to be firft furrounded with a Ditch, leaving here and there fome Canals, or Apertures, in it; to thefe apply Water-Engines and work out the Water; then cover the Ground with Dung, and fow in it fuch Seeds as are of a quick Growth, viz. Mustard-feed, Coleworts, and the like. The Dutch are very expert at draining Lakes by this Method; and often convert them into fruitful Meadow-Ground. At this time they are confulting how to drain the Lake of Harlem, and I do not doubt but it will be, fome time or other, attempted; because this Lake covers much Ground which by draining would be of great Use to the Inhabitants.

PROPOSITION XI.

Moraffes, or Leaches, are of two forts; some are oazy and confift of Earth and Water mixed together, fo as not to bear the Footsteps of Men: others are Ponds, or scanty Collections of Water, interfpers'd here and there with fmall Spots of Land.

THOSE of the former kind neither receive nor emit Rivers, we call them Sloughs or Bogs; there are many in Holland. In Brabant there is a

large

Thofe of the later
Heads of Rivers,
Moraffes; as the
and of the Nile.

large one called Peel-marsh. There are also several in Weftphalia of both Sorts. kind are chiefly found at the whence fome call thefe Heads Moraffes of Tanais in Muscovy, There are several of thefe in the Province of Savolax in Finland, which cover vast Tracts of Ground; alfo thofe [called Enare-Trek] in Lapland; the Marshes of Chelours in Africa, the Moraffes thro' which the Euphrates runs in Chaldæa, &c. fuch as these are also found in Woods and heathy Defarts, and are made by the Rain-water gathered into hollow Places, whereby the Earth is foaked and moistened, and the Rays of the Sun are hindered from drying it up, by the Leaves of the Trees and the Heath. Thefe are found chiefly in Germany

and Muscovy.

THE narrower fmall Lakes, like the larger Sort, do fome of them both receive and emit Rivers; fome only receive, others only emit, and the rest neither receive nor emit any.

THE first fort are formed and fed, partly by Springs under Ground, and partly by Rain-water which ftagnates for want of a Chanel to carry it off. Of this fort there are many in Muscovy and Finland. The fecond fort are generated from fmall Springs, and are fed by them and Rain-water,

ARISTOTLE calls the Sea of Maotis a Lake, which is truly fo.

PROPOSITION XII.

Bogs contain a fulphureous, bituminous, and fat, Earth.

THIS is apparent from the black Colour of the Turf that is got out of them, which eafily takes fire, (as in Holland and other Places) by reason this fort of Matter is contained both in the Rain

and in the Ground, where thefe Lakes are fituated. But all Bogs have not that fort of Earth: and where the Ground is hard and rocky we felcom find any Lakes; and therefore most part of them contain a foft fpongy and fulphureous fort of Earth.

PROPOSITION XIII.

To drain, or dry up, a Bog.

THO' fome Bogs are of a great Depth, yet no more is required than to drain them to a certain level, which may be done feveral ways; 1. By making a Chanel to carry off the Water. 2. By throwing in plenty of dry Earth, when they are almoft dried up by the Heat of the Sun. 3. By fetting their Surfaces on Fire. 4. By turning the Water that feeds them, another way.

CHAP.