He that is acquainted with the situation of England, and can reflect on the vast Quantities of flat Grounds, on the Banks of all our navigable Rivers, and the Shores of the Sea, which Lands at Least lying under Water every Spring-Tide, and being thereby continually full of moisture, were like a stagnated standing body of Water brooding Vapours in the Interval of the Tide, must own that at least a fifteenth part of the whole Island may come into this Denomination.
Let him that doubts the Truth of this, examine a little the Particulars; let him stand upon Shooters-Hill in Kent, and view the Mouth of the River Thames, and consider what a River it must be when none of the Marshes on either side were wall'd in from the Sea, and when the Sea without all question flow'd up to the Foot of the Hills on either Shore, and up every Creek, where he must allow is now dry Land on either side the River for two Miles in breadth at least, sometimes three or four, for above forty Miles on both sides the River.
Let him farther reflect, how all these Parts lay when, as our ancient Histories relate, the Danish Fleet came up almost to Hartford, so that all that Range of fresh Marshes which reach for twenty five Miles in length, from Ware to the River Thames, must be a Sea.
In short, Let any such considering Person imagine the vast Tract of Marsh-Lands on both sides the River Thames, to Harwich on the Essex side, and to Whitstable on the Kentish side, the Levels of Marshes up the Stour from Sandwich to Canterbury, the whole Extent of Lowgrounds commonly call'd Rumney-Marsh, from Hythe to Winchelsea, and up the Banks of the Rother; all which put together, and being allow'd to be in one place cover'd with Water, what a Lake wou'd it be suppos'd to make? According to the nicest Calculations I can make, it cou'd not amount to less than 500000 Acres of Land.
The Isle of Ely, with the Flats up the several Rivers from Yarmouth to Norwich, Beccles, &c. the continu'd Levels in the several Counties of Norfolk, Cambridge, Suffolk, Huntingdon, Northampton, and Lincoln, I believe do really contain as much Land as the whole County of Norfolk; and 'tis not many Ages since these Counties were universally one vast Moras or Lough, and the few solid parts wholly unapproachable: insomuch that the Town of Ely it self was a Receptacle for the Malecontents of the Nation, where no reasonable Force cou'd come near to dislodge them.
'Tis needless to reckon up twelve or fourteen like Places in England, as the Moores in Somersetshire, the Flat-shores in Lancashire, Yorkshire, and Durham, the like in Hampshire and Sussex; and in short, on the Banks of every Navigable River.
The sum of the matter is this; That while this Nation was thus full of standing Lakes, stagnated Waters, and moist Places, the multitude of Exhalations must furnish the Air with a quantity of Matter for Showers and Storms infinitely more than it can be now supply'd withal, those vast Tracts of Land being now fenc'd off, laid dry, and turn'd into wholsome and profitable Provinces.
This seems demonstrated from Ireland, where the multitude of Loughs, Lakes, Bogs, and moist Places, serve the Air with Exhalations, which give themselves back again in Showers, and make it be call'd, The Piss-pot of the World.
The imaginary Notion I have to advance on this Head, amounts only to a Reflection upon the Skill of those Ages in the Art of Navigation; which being far short of what it is since arrived to, made these vast Northern Seas too terrible for them to venture in: and accordingly, they rais'd those Apprehensions up to Fable, which began only in their want of Judgment.
The Phœnicians, who were our first Navigators, the Genoese, and after them the Portuguese, who arriv'd to extraordinary Proficiency in Sea Affairs, were yet all of them, as we say, Fair-weather Sea-men: The chief of their Navigation was Coasting; and if they were driven out of their Knowledge, had work enough to find their way home, and sometimes never found it at all; but one Sea convey'd them directly into the last Ocean, from whence no Navigation cou'd return them.