Downs, Chacewater, and Huel-Virgin. I know that some may say, if this be the cafe, these Mines will be again renovated. Probably this, in a certain degree, will be the case: but let it be remembered, that where the nidus with the decompofing matter is taken away, the Water from the circumjacent ftrata, instead of percolating through the vein, falls into a congregated fluid of its own kind. Indeed, where any of the vein is left in whole, as we call it, we fee no reason why it should not have the fame effect there as formerly; nay, we are of opinion, that where a Mine has been wrought till the Lode has proved barren in quality, and is left off from extreme poverty, if the vein continues, and is endued with the fame decompofing and attractive qualities as the part formerly wrought originally might have been, fuch Lode may probably be converted into Ores, by the Water now percolating through it, and faturated accordingly.

The Miners often feel a palatable difference in Water under ground, at a great depth; for if they tafte a clear stream of Water, as it flows down upon the walls of the Lode, it is either very cold or almost lukewarm, or infipid or fweet. In Copper Mines particularly, we fometimes find the Water full as warm as new milk in one part of the mine, while it is very cold in another; nay, in several of these, particularly in Huel-Musick and Huel-Rose, the writer has stood with one foot in the warm, and the other in the cold Water, and has divided and diverted them different ways. In the former of these Mines, the difcovery of this warm Water, has always immediately preceded a confiderable enlargement of the Lode, and richness of the Ore. In the latter, the cause is not so absolutely determined; as the Lode from which it is known to proceed, has not been discovered at that depth; but where it has been fo, it greatly abounds with fulphurcous Minerals.

On the other hand, the Water which flows through a bed of Tin, is generally very fine, foft, and infipid; especially if the Lode or ftrata are of the Grouan or Elvan kinds, and the Tin rich in quality and homogeneous. Our clean Pryan Tin Lodes likewife yield a foft alkalefcent Water, that, I am fatisfied, would be of fingular service to all perfons afflicted with acidities in the primæ viæ.

Springs are either temporary or perennial: fome fay, that they originate from vapour, rain, or dews, collected on the

fides of mountains, and are thence commiffioned into the bowels of the earth, in form of fprings; others, that they proceed from the deep abyfs; and others, that they are filtrations from the sea, into which all the rivers run, as into the place from whence they came, per modum circulationis. For, "all "the rivers run into the sea, yet the sea is not full; unto the place from whence the rivers came, thither they return again."

The theory of Meff. Marriotte and Perault, that springs have their origin from rains, hath been examined and confuted by Mr. de la Hire. Dr. Halley's hypothefis, of their being produced by vapours, though the most popular, is in a manner overturned, in our opinion, as well as the former, by Mr. Derham's perennial spring in the parish of Upminster, and various others. in different parts. Of those who have mentioned that, which we conceive to be the only true origin of perpetual springs, THE OCEAN, none have, to our knowledge, affigned the quo MODO or proper cause; and therefore leave it undetermined, or rather give up their unsupported argument in favour of Dr. Halley's more plaufible and commonly received, though more erroneous, hypothefis, of its being effected by the condenfation and precipitation of vapours and dews from the tops of moun

tains.

The ftrefs of our argument and the novel part of our hypothefis, is, that in the formation of perpetual fprings, they not only derive their Waters from the fea, by ducts and cavities running from thence through the bowels of the earth, like veins and arteries in the human body; but that the fea itself acts like a huge forcing engine, or hydraulick machine, to force and protrude its waters from immenfe and unfathomable depths, through thofe cavities, to a confiderable inland distance.

One of the hydrostatical laws of fluids, being, that their preffure is in the ratio of their perpendicular altitudes, how very great, how immenfe muft that preffure be, in the unfathomable parts of the fea! and, indeed, in those parts, which, as Varenius affirms, have been fathomed to the depth of four miles and a half! Only conceive (if poffible) a forcing engine, or the best hydraulick machine, acting with a force equal to this immenfe preffure, upon a body of water, in order to carry it to any distance whatever, or raise it to any conceivable height! Imagine then, with what inexpreffible force the water from such a preffure, must be protruded through those cavities, ducts, and E hollow

hollow paffages, from the bottom of the sea, through the bowels of the earth, to various parts of its furface, where they discharge themselves, as through fo many tubes or pipes, and form perpetual fprings; fome rifing, either from a duct of lefs perpendicular depth, where the preffure is not fo great, or otherwise more perpendicularly than others; confequently, in either cafe, at a lefs diftance from the fubaqueous mouth of the duct; whilst others, running more horizontally, or derived from a greater depth, where the preffure is proportionably ftronger, or, perhaps, from the duct tending for a confiderable length towards the center of the earth, are forced to a greater inland distance, in the confined tubes or veins of the earth, before they emerge to the furface, which we apprehend they do from various orifices and branches, like capillary tubes from a principal artery: the preffure of the fluid acting in this inftance, as in all others; and the immenfity of that preffure in the fea feeming to justify our calling it a huge forcing engine, and comparing it to an hydraulick machine, whofe power we can easily conceive to be fufficient, from the convexity and globular form of the fea as well as the land, to force its Waters through the aforefaid capillary tubes to the tops of the higheft mountains, even without the aid of attraction, which, not improbably, may in fome cafes contribute fomewhat towards their afcent.

That which gave birth to our conjectures, and led us into these reflections, was the confideration of the Caspian fea, as having no vifible outlet; moft of whofe rivers, which difgorge themselves into that grand refervoir, we conceived as deriving their origin from the fea itself, being forced, by the preffure of the atmosphere and watery fluid, through fubterraneous ducts and channels to certain distances, where they emerge in fprings and bubbling fountains; and increasing as they approach nearer to the fea, by the acceffion of other Waters from other ducts, are fwollen into confiderable rivers of fresh Water, affording conftant supply to keep that grand refervoir" without o'er"flowing full;" which freshness, we confider, and suppose it is generally confidered, as effected by the falt water being filtrated and ftrained through a confiderrble body of earth in its paffage from the sea to the fountain head. As a juftification of this fuppofition, we beg leave to mention, the brackifhnefs of thofe fprings, which is frequently complained of near the sea coafts; and which is undeniably occafioned by their vicinity to the fea, whofe Waters are not filtrated through a sufficient body

of

of earth, totally to deftroy their faltnefs, and render them quite fresh.

We do not, however, fuppofe, that all the rivers which empty themselves into the Cafpian or any other sea, are always derived from that particular fea into which they return: for inftance, we conceive the head of the Wolga river to be more probably derived from the Frozen-fea, to which its fource is much nearer than to the Cafpian-fea; and which feems even neceffary, in order to fupply that quantity of fluid, which must be constantly evaporating from its furface, for the fupply of dews, rains, &c. for an extensively furrounding country. Again; it is probable, that the Nile takes its fource from the Eastern-ocean or Red-sea, rather than from the Levant or Mediterranean into which it runs: also, that the river Amazones, takes its rife from the Pacifick-ocean, and not from the Atlantick-ocean into which it flows and fo of various other foreign rivers, which, though they may take their origin as we have here supposed; yet we further fuppofe, that as they arrive nearer to their mouths, they may be and are confiderably increased, and receive large additions, by the like ducts and channels, from that sea likewise into which they run.

To illustrate this hypothefis, we fhall mention one inftance more in our own country, of the river Tamer, which divides Devonshire from Cornwall; whofe head rises, we suppose, from the Bristol-channel, within five or fix miles from Hartlandpoint; and after running near an hundred miles due fouth, empties itself into the English-channel at Plymouth; whilst the river Torridge, which rifes on the fame common, and within the distance of a few cloth yards from the Tamer, after a course of upwards of fifty miles, difgorges itself again into the Bristolchannel in Barnftaple-bay, not twenty miles N. E. from its head.

Let us adduce the rise of these two rivers, as pofitive proof against Dr. Halley's ingenious hypothefis. "Their heads are two perpetual springs within a few yards of each other, on the pretty level fummit of a vast high common, one of the highest "in all the neighbourhood; where there are no rocks or crannies " for the vapours or dews to gleet down by, nor any mountains

or caverns above it to collect a body of water; nor any one "circumftance favourable to his hypothefis." Letter from Christopher Gullet, Efq; of Exeter.

The

The Waters with which our Mines abound, are derived both from temporary and perennial fountains; and are very properly distinguished with us, by the names of Top and Bottom Water. Shallow Mines have very little Water, more than comes from the furface; and it is temporary, according as the seasons vary; fo that, without a competent power to draw out the Water from the workings, the adventurers are generally obliged to ftop them, or "Knock the work," as the phrafe is, foon after the autumnal equinox; otherwife, which is frequently the cafe, they expose themselves to a great expence, difappointment,

and lofs.

Our very deep Mines are fubject to Water from both the fources before mentioned; for in the drieft feafons we know of, they have a conftant ftream ab interno, which requires much expence and addrefs to keep under: but in the depth of winter, when all the earth is drenched as it were with moisture, we are vifibly affected by the concurring ftreams both of Top and Bottom Water; notwithstanding all precautions are used, to take up the superficial streams, by launders or grooves cut in the walls or fides of the Lode, to convey them either into the adit or tye lift of pumps, by which the burthen is eafed for the engine, and the bottoms are freed from fo much Water.

The deepest of our Mines are not much affected by the influx of Top Water, before the depth of winter; as it takes till that time, to fill the interstices of the earth or ftrata, and protrude its redundant ftream to the deep bottoms. Our most experienced Miners will fay, that "A dry eafterly wind raises the fprings;" but although it may appear fo to our outward fenfes, yet a little application to the folution of this phenomonon, will fhew the conclufion to be falfe.

During three parts in four of the year, the wind blows from the intermediate points of the weft and the fouth; and coming over a large tract of the Atlantick-ocean, and confequently fraught with much wet, difcharges its moisture, as foon as the current of air, which fufpended the clouds, is diminifhed and broke by the cliffs and hills. It was an obfervation made by our Saviour, that the western winds brought rain in Judæa: Luke xii. 54. The fouth wind coming from the coast of Africk, had the fame effect in the Adriatick: Horace Lib. i. Ode 3. The weft wind is often fo fierce and raging after acquiring ftrength in the Atlantick-ocean, that it is fcarce

conceivable