ignorant and shall I fear long continue so For it is to be noted with which observation I shall conclude that what has been hitherto discoursed belongs only to the Temper of those Subterraneall parts to which men have been enabled to reach by Diging 'T is true indeed that some Mines especially in Germany and Hungary are of a Stupendious depth in comparison of the generality of ours and of the more obvious Cavities of the Earth yet I find it boasted in a Discourse written purposely of the Various Mines in the VVorld that the rich Mine at Sueberg is 400 yards deep And they are scarce believed that relate one Hungarian-Mine which they visited to be 400 sathom which though double the depth of the former reaches not to half a mile But the deepest of all the mines that I have as yet read or heard of from any credible Relator is that which the experienced Agricola in the Tract he calls Bermannus Cap. 12. mentions to be at Cotteberg But this it self though it reach to above 500 fathom that is 3000 foot yet this prodigious depth dos not much exceed halfe a mile fals short of three quarters Licet variae de ambitu tervae opiniones sint nobis tamen propemodum constet esse ipsam milliarum Italiarum 26255 quod in maximo ad Terrae superficiem circulo respondeant uni gradui milliaria proximè 73. c. Gassend Instit Astronom Lib 2. Cap. 13. and how small a part is that of the whole depth of the Terrestriall Globe whose semidiameter if we admit the recent account of the Learned Gassendus reckoned at 4177. Italian miles in comparison of which as I was saying how small a thing is a depth that falls very short of a single mile FINIS Of the TEMPERATURE Of the SUBMARINE REGIONS As to HEAT and COLD OF THE TEMPERATURE Of the SUBMARINE REGIONS As to Heat and Cold. CHAP. I. THough the Aristotelians who believe water and Aire to be reciprocally transmutable doe thereby fancy an Affinity between them that I am not yet convinced of yet I readily allow of so much Affinity betwixt those two fluid Bodies as invites me after having treated of the Temperature of the Aeriall Regions to say something of that of the Submarine Regions which name of Submarine though I know it may seem Improper I therefore Scruple not to make use of because even among the Generality of Learned Men use has Authorized the name of Subterraneous Places For as these are not by this name and indeed cannot in Reason be supposed to be beneath the whole Bodie of the Earth but only the Superficiall parts of it so by the Appellation of Submarine Regions 't is not to be supposed that the places so called are below the Bottom of the Sea but only below the surface of it But to come from words to things I presume it will not be expected that I that never pretended to be a Diver should give of the Regions I am to treat of an Account build on my own Observations and I hope it may gratifie a Reasonable Curiosity about a subject of which Classick Authors are so very silent and about which Philosophers seeme not so much as to have attempted any Experiments for want of Opportunities and mean to make them I offer the best Information I could supply my selfe what by purposely conversing with Persons that have dived some without and some by the help of Engins To which I have added some reports that I judge fit to be allowed made me by Persons that had conversed with the Divers upon those Affrican and Indian-Coasts where the most famous and expert are thought to be found And I the rather report the Answers and Relationsmy Inquiries procur'd because the Informations they give us concerne a subject considerable as well as vast about which neverthelesse I among many others am not in a condition to satissie at all my Curiosity by Tryalls of my own making and because also what I shall say will probably spoile the credit of the Vulgar Error that in all deepe water of which the Sea is the Cheifest the lowermost are still the warmest parts unlesse in case that in some very hot Climates or seasons the superficiall ones happen to be a little warm'd by the Extraordinary or Violent heat of the Sun CHAP. II THough the Air and the Earth have been discriminated as to Temperature into three Regions yet the Informations I have hitherto met with invite me not to assign to the Sea any more then two The former of which may be supposed to reach from the superficies of it as far downwards as the manifest operation of the variously reflected and refracted Beames of the Sun or other Causes of warmth penetrates from which to the Bottom of the Sea the other Region may be supposed to extend According to this Division the Limits of this upper Region will not be alwaies constant for in the Torrid Zone and other hotter Climates it will Caeteris paribus be greater then in the Frigid Zone or in the Temperate Zones and so it will be in Summer then in Winter and in hot weather then in Cold supposing in these Cases the Heat to come from the Sun and Air and not as sometimes it may do from the Subterraneall Exhalations The same causes are likewise proper as 't is manifest to alter the Temperature as well as the Bounds of this Region But this Temperature may also be changed in some few places by at least two other Causes The one is the differing constitution of the Soil that composes the Shore which may affect the neighbouring water if it doe extraordinarily abound with Nitre loosely contexed marchasites or other substances capable considerably to encrease or lessen the Coldnesse of the water Another though unfrequent Cause may be the figure and situation of the lesse deep parts of the Shore which may in some sort reverberate the Heat that proceeds from the Sun and upon such an account may either add to the warmth or allay the Coldnesse that would else be found in the neighbouring water For whatever the Schools are wont to teach about the Interest of the Attrition of Air in the heat produced by the Sun Beams I have elsewhere shown by Experiments that those Beams may considerably operate upon Bodies placed quite under water Besides these two Cases that may occasion Exceptions to the generall Observation I intimated by the words at least that there might be others Because to mention now but one Example though it seem probable from what I have elsewhere delivered concerning the Subterraneall Fires and Heats that may in some places be met with even beneath the bottom of the Sea that the Phaenomenon I am going to recite may be reduc'd to the causes newly intimated yet I am not absolutly certain but that in this case whereto some others may perhaps be found resebling some other cause then those hitherto mentioned may produce or concurre to the
effect The Relation here meant is afforded us by the following Passage taken out of the Voyage of Monsieur de Monts into New-France whereof he went to be Governor where the Relator thus recites his observation About the eighteenth day of June we found the Sea-water during three dayes space very warm and by the same warmth our wine also was warme in the bottom of our ship yet the Air was no hotter then before And the 21 of the said moneth quite contrary we were 2 or 3 days so much compassed with mists and cold that we thought our selves to be in the moneth of January and the water of the Sea was extreame cold which continued with us untill we came upon the Bank by reason of the said mists which outwardly did procure this cold unto us This effect he attributes to a kind of Antiperistasis in the following part of his narrative which I shal not now either transcribe or examine CHAP. 3 And thus much being breifely noted touching the upper Region of the Sea and the requisite Cautions that may perhaps extend further then it being premised it remains that I take notice of the Temperature of the Lower Region which in one word is Cold unlesse in some few places to be presently mentioned For water being in it's naturall or most ordinary state a liquor whose parts are more slowly agitated then those of mens Organs of Feeling must be upon that account Cold as to sense and consequently it need not be strange that those parts of the Sea which are too remote to be sensibly agitated by the Sun-Beams or wrought upon by the warmth which the Air and upper parts of the Earth may from other Causes receive should be felt Cold by those that descend into it unlesse in those few places where the Coldnesse may be either expell'd or allay'd by hot Springs or Subterrestriall Exhalations flowing or ascending from the subjacent Earth or the lower parts of the shore into the incumbent or adjacent parts of the water To justifie my ascribing of this Coldnesse to the second or lower Region of the Sea I shall now subjoin some Relations I procur'd from persons that had occasion to goe down into it or otherwaies take notice of its Temperature in very differing Regions of the World and at very unequall depths And first as to the Temperature of the lower Region in the Northerne Sea I had the opportunity to converse often and sometimes to oblige a man bold and curious enough who for some years got the best part of his subsistence by descending to the bottom of the Sea in an Engin whose structure I elsewhere describe to seek for and recover Goods lost in Shipwrackt Vessels This person I diligently examined about divers Submarine Phaenomena about which his answers may be elsewhere met with And as to the Temperature of the lower parts of the Sea the knowledge of which is that alone that concerns us in this place he severall times complained to me of the Coldnesse of the deep water which kept him from being able to stay in it so long as he might have been put into a condition of doing by the goodnesse of his Engin for I remember that he related to me that he staid once betwixt an hour or two at a depth that was no greater then 14 foot and a half upon the coast of Sweden in a place that was near the shore and I afterwards learnd that he staid much longer in a deeper place use having probably made the Cold more supportable to him He told me then that about two years before he was engaged by a good reward to goe down with his Engin to the bottom of the Sea to fetch up some Goods of value out of a Ship that had been cast away there within about a miles distance from a very little Island and if I mistake not about 6 miles from the Shore He farther answered me that though he felt it not at all Cold on the Surface of the Water his attempt being made in June yet about the depth of the Ship it was so very Cold that he felt it not so Cold in England Winter and Frosty VVeather And he told me that an excessive Cold was there felt not only by him but by very sturdy men who invited by his example would needs also goe down themselves to participate and promote the hoped for Discovery He told me also that the upper water did but cool and refresh him but the deeper he went the Colder he felt it which is the more considerable because he had some times occasion to stay at 10 fathoms or even 80 foot under water And I since found that he informed divers Virtuosi that purposely consulted him that he found the Coldnesse of the Water encrease with its depth and gave that for the reason why he could not stay so many hours as otherwise he might at the bottom of the Sea Adding that before his Engin was well fitted he was once so covered over with it that he was forced to touch the ground with his hands and feet and the neighbouring parts to which he found a Coldnesse communicated by the Fundus he lean'd upon though the closenesse of his disordered Engin made the other and whilst he was in that posture upper parts of his Body of a very differing Temper An inquisitive person of my acquaintance that made a long stay in the Northerne America at about two or three and forty degrees of Latitude and diverted himselfe often with swimming under water answered me that though he scarce remembred himselfe to have dived above two fathoms beneath the surface of the Sea yet even at that small depth he observed the water to increase in coldnesse the lower he descended into it Which argues that though the Sun-Beams do often penetrate plentifully enough to carry light to a great depth under water yet they doe not alwaies carry with them a sensible heat and that at least in some places the upper Region of the Sea reaches but a little way The coldnesse of the Climate in these western parts of Europe and the want of considerable inducements to invite men to dive often to any great depth into our Seas has kept me from being able to procure many observations about the temperature of their lower Region but upon the hotter Coasts of Africk and the East-Indies the frequent Invitations men have to dive for Corall pearles and other Submarine Productions has made it possible for me to get more numerous observations some of which I shall now annex CHAP. 4. MEeting with a Person of Quality who had been present at the sishing of Corall upon the shoar of Africa and Who was himselfe practised in diving I inquired of him whether he found the Sea upon the African Coast to be much colder at a good depth then nearer the surface whereto he answered me that though he had seldome dived above three or four fathoms deep yet at that depth he found it so much
colder then nearer the Top of the water that he could not well endure the coldnesse of it And when I farther asked him whether when he was let down to the bottom of the Sea in a great diving Bell as he told me he had been he felt it very cold though the water could not come immediately to touch him he replyed that when the bell came first to the ground he found the Air in it very cold though after he had staid a while there his breath and the steams of his Body made him very hot That also at a greater depth in those hotter Climates the Sea-water is sensibly Cold may be thus made probable Inquiring of a famous Sea-Commander who had been upon the Affrican Coast to what depth he was wont to sinck his Bottles to preserve his Wine any thing coole in that excessive hot Climate he Answered me that in the day time he kept it in a tolerable temper so as to be drinkable by keeping it in the Bottom of the ship and in sand but in the morning he had it coole enough by sincking his Bottles over night into the Sea and letting them hang all night at 20 or 30 fathom deepe under water Inquiring also of an intelligent Gentleman that was imploy'd to the river of Gambra sayl'd up 700 miles in it in a small frigot whether he had observed that in the Sea even of those hot climats wine may be preserved coole he told me that it might and that by the means I hinted to him which was to let down when the ship came to an Anchor in the Evening severall Bottles full of wine they used that of Madera exactly stoped to ten 12 or 14 fathoms deep whence being the next morning drawn up they found the wine coole and fresh as if the vessels had been in these parts drawne up out of a well provided it were presently drink for if that Circumstance were omitted the heat of the Aire on the upper part of the water would quickly warme the Liquor I remember too that having met with a man of Letters that sail'd to the East-Indies in a Portugal-Caraet I learnt by enquiry of him that 't was the practice in that great Vessell for the Captain and other Persons of note whilst they passe through the Torrid Zone to keep their Drink whether Wine or Water cool by letting it down in bottles to the depth of 80 90 anc sometimes an hundred Fathom or better and letting it stay there a competent time after which he told me he found it to be exceeding cool and refreshing Lastly to satisfie my selfe as far as I could to how great a depth the Coldness of the Sea reached meeting an observing Traveller whose affairs or Curiosity had carried him to divers parts both of the East and VVest-Indies I enquired of him whether he had taken notice of any extraordinary deep soundings in the vaster seas To which being answered that some years agoe sailing to the East Indies in a very great ship over a place on the other side the Line that was suspected to be very deep they had the Curiosity to let down 400 Fathom of Line and found they needed no lesse Whereupon I enquired of him whether he had taken notice of the Temperature of the sounding Lead assoon as 't was drawn up To which he told me that he and some others did and that the Lead which was of the weight of about 30 or 35 l had received so intense a degree of coldnesse as was very remarkable insomuch that he thought that if it had been a masse of Ice it could not have more vehemently refrigerated his hands and when I asked in what Climate this observation was made he told me 't was in the Antarctick Hemisphere but at a great distance from the Line As indeed I concluded by some Circumstances he mentioned to me that 't was about the 35th degree of Southern Latitude CHAP. 5. These are the cheife Relations I have hitherto been able to procure about the Temperature of the Sea which if they be so confirmed by others as that we may conclude they will generally hold it wil not be irrational to conceive that in reference to Temperature those two Fluids Air and Water may have this in common that where their Surfaces are contiguous and in the neighbouring parts they happen to be sometimes cold and sometimes hot as the particles they consist of chance to be more or lesse agitated by the variously reflected Sun-Beams or more or lesse affected by â—ther causes of Heat But that part of the Air which they call the second is superior to the first as also the lower Region of the Sea being more remote from the operation of those causes doe retain their naturall or more undisturbed Temperature which as to us men is a considerable degree of coldness the Agitation of their small parts being usually in those Regions much inferior to that of the Spirits Blood other parts of our Organs of Feeling So that the Regions of the water and Air seem to answer one another but in an inverted order of situation and the Analogie might perhaps be carryed further if I had time and opportunity to doe it in this place And here I shall not dissemble that I was somewhat perplexed by meeting with a traveller that had visited the East Indian Coast near the famous Cape of Comory for asking him some questions touching the neighbouring Sea I gathered from his discourse that he concluded from that of some Divers that the Sea near Ceylom was warmer at the bottom then at the top And when I thereupon asked him whether this happened not in their Winter he replyed that it was indeed Winter though not with us yet with them it occurr'd indeed to my thoughts on this occasion that perhaps in a part of the Torrid Zone so near the Line as about 80 degrees if the Sea were not of a considerable depth the heat of the two not far distant shores of Coromandell and Ceylom might have no small influence upon the Tempetature of the water I considered also which did not a little weigh with me that in divers parts of the East-Indies and even in a Region bordering upon Coromandell where an ingenious Acquaintance of mine lived some years it has been observed that Winter and Summer are not so much discriminated by Cold weather Hot as by very Rainy weather and very dry Nay in some places the sultry heat of the Climate is more complained of in what they call their Winter then their Summer So that there will be no necessity to recur to an Antiperistasis occasioned by the coldnes of the Winter I thought too that it may perhaps be without absurdity suspected that as the bottom of the Sea in this place had a peculiar Constitution that fitted it more then others for the copious production of pearls so there might be some peculiarity in the nature of the subjacent Soil or there may be
The Tract here pointed at is a Discourse of Subterraneall Fires and Heats that many of them will conceive a very considerable degree of heat will it not be very probable that the Temperature of the Earth in the place that abounds with these Marchasiticall mineralls will be very warm in comparison of the Temperature of the other place where the Soil dos plentifully produce nitrous and other refrigerating Bodies though both the places be supposed to be at the same distance from the surface of the Earth and consequently in the same Subterraneous Region Upon the like grounds it may also be suspected that in the same places the Temperature may not be alwaies the same even upon the account of the Soil For I elsewhere shew that some Saline Earths especially nitrous and some mineralls that partake of the nature of marchasites admit a kind of graduall maturation and perhaps other Changes that seem to be spontaneous And that such changes happen the more notably in those parts of such Bodies that are exposed to the Air as those are that chance to be placed at the sides of the deep Wells we are talking of Which things being presupposed 't will not be absurd to conceive that the minerall to which either heat or cold is to be referr'd may be more copious ripe and operative at one time then at another or that at length all the Earth capable of being as it were Assimilated by the minerall rudiments harbour'd in it may be consumed or the minerall it selfe may arrive at a perfection of maturity which will make its texture so close as to be unfit to be penetrated and wrought upon as before by the water or other Liquor that occasioned its incalescence CHAP VII I Omit to speak of the transient changes that may be occasion'd in the temperature of the second Region of the Earth by severall Accidents and especially by the Subterraneall Exhalations that in some places and times copiously ascend out of the lower Regions of the Earth Nor shall I insist upon any of the other causes of a more durable difference of temper in some parts of the second Region such as may be the Vicinity of Subterraneall Fires in the third Region that heat the incumbent Soil because I would hasten to the Third and last part of this Discourse which yet I must not do without premising this advertisement that I think my selfe oblig'd to speak the more hesitantly and diffidently about the Temperature of Subterraneall Air because mineralists have not had the Curiosity to examine it by Weather-glasses which would give us much more trusty Informations then our sense of feeling powerfully preaffected by the cold or heat of the externall Air. I did indeed send fitt Instruments to some daies journey from this place to examine the Air at the bottom of some of our deep mines but through some unlucky casualties upon the place the attempt miscarried But when I shall God assisting recover an opportunity that I have since wanted I hope an accurate seal'd Weather-glasse join'd with a portable Baroscope will give me better Information then mineralists have yet done I say a seal'd Weather-glasse because though common Thermoscopes had been employed by miners I durst not rely upon them being perswaded by tryalls purposely made as well as by the Reason of the thing of the Fallaciousnesse of such Thermoscopes for in them the included Air is liable to be wrought upon not only by the Heat and coldnesse but by the weight or Pressure of the externall Air. So that if a Thermoscope be let down from a very considerable height at the top of which the station of the pendulous Liquor be well markt that Liquor will be found to have risen when the Instrument rests at the bottom as if the included Air were manifestly refrigerated though the temper of the externall Air may be in both places alike the cause of the pendulous Liquors rising being indeed that the Aereall pillar incumbent on the stagnant Liquor is higher and heavier at the bottom where the Instrument rests then that which lean'd upon it at its first or upper station nearer the top of the Atmospher From whence 't will be easy to conclude that at the bottom of a deep Groove where the Atmosphericall pillar that presses the stagnant water will be much longer and heavier then at the top the Air may appear by the Instrument to be colder in places where 't is really much hotter the increased weight of the incumbent Air being more forcible to impell up the pendulous Liquor then the indeavour of expansion procur'd in the included Air by the warmth of the place is to depresse it CHAP. VIII THat which challenges the third and last part of my discourse is the lowermost Region of the Earth about whose temperature I shall comprize what I have to say in the following Proposition Proposition the 4. The third Region of the Earth has been observed to be constantly and sensibly warm but not uniformly so being in some places considerably hot I mention that the recited temperature has been observed in the Lower Region because I would intimate that I wovld have the proposition understood with this Limitation as far as has been yet that I know of observed For allmost all the deep Grooves that mineralists have given us accounts of and wherein men have wrought long enough to take sufficient notice of the Temperature of the Air have been made in Soils furnished with metalline Oars or other mineralls without which men would not be invited to be at so great a charge as that of sinking so very deep pits and maintaining work-men in them So that experience has yet but slenderly or at least not sufficiently informed us of the Temperature of those parts of the third Region of the Earth that are not furnished with ponderous mineralls and consequently has not informed us of the Temperature of the Lowermost Region in generall as will better appear by what I shall ere long represent Having premised this Advertisement about our proposition we may proceed to the distinct proofe of the two parts or members it consists of And to begin with the first whatever the Peripateticks teach of the innate Coldnesse of the Earth especially where 't is remotest from the mixture of the other Elements yet having purposely inquired of severall persons that visited and also frequented the Third Region in differing Countries Soils and at differing depths under ground and Seasons of the year I did not perceive that any of them had ever found it sensibly and troublesome cold in the Third Region of the Earth And on this occasion I remember I had some light suspition that at least in some Cases the narrowness of the Cavities wherein the Diggers were in divers places reduc'd to worke might make the warmth they felt proceed in great part from the Steams of their own Bodies and perhaps of the mineralls and from the Difficulty of cooling or ventilating the Blood in an
Air clogg'd with steams And I was the rather induced to thinke this possible because I had even in metalline mines that were but shallow and very freely accessible to the Air observed a strong smell of the metall abounding there I have likewise found by severall tryalls that the exhalations that proceed from the Bodies of Animalls doe so vitiate the Air they abound in as to make it much less fit for their Respiration and to be apt to make them sick and faint Wherefore I thought it not altogether unfit to inquire whether the heat of the Subterraneall air in such places as have been newly mentioned might not be referr'd to these Causes But I was answered in the negative especially by an inquisitive person that had been in the deepest and hottest mines that have been visited by any Acquaintances of mine This way of accounting for the Subterraneall Warmth being laid aside it seem'd I confesse somewhat difficult to conceive how it should be produced yet two principall Causes there are to which I thinke we may probably refer the Temperature of those places where the air is but moderately warm To which a Third is to be added when we come to give an account why some places are troublesomly hot And first why the Coldnesse of Winter should not be felt in the Lowermost Region of the Earth may be that the air there is too remote from the Superterrestriall air to be much affected with those adventitious Causes of Cold that make that Quality intense in the air above ground But because this Reason shews rather why it should not be in the Earths Lower Region much Colder in Winter then in Summer but not why it should be in all seasons warm there I shall add as a Conjecture that the positive cause of the actuall warmth may proceed from those deeper parts of the Subterraneall Region which ly beneath those places which men have yet had occasion and ability to dig For it seems probable to me that in these yet inpenetrated Bowells of the Earth there are great store-houses of either actuall Fires or places considerably Hot or in some Regions of both from which Reconditories if I may so call them or magazines of hypogeall heat that quality is communicated especially by Subterraneall Channells Clefts Fibres or other Conveyances to the less deep parts of the Earth either by a propagation of heat through the substance of the interposed part of the Soil as when the upper part of an Oven is remissly heated by the same Agents that produce an intense heat in the Cavity or by a more easy diffusion of the Fire or heat through the above mentioned Conveyances as may be exemplified by the pipes that convey heat in some Chymicall structures Or else which is perhaps the most usuall way by sending upwards hot minerall Exhalations and Steams which by reason of the comparatively heavy materialls they consist of and by reason of their being lesse dispersed nearer the places whence they proceed are usually more plentifull in the deeper parts of the Earth and somewhat affect them with the Quality that they brought from the workhouses where they were form'd and that they retain for some time after CHAP. IX THat manifest Steams oftentimes are found in Grooves especially in deep ones is evident by the damps that infest most of them and that in distant Regions as in severall provinces of Germany Bohemia Hungary c. as also in severall parts of England in Grooves some of which I have received Relations from the mine-men themselves By which it appears that severall of these Exhalations ascending from the entralls of the Earth are sulphureous Bituminous in smell and in some Grooves one whereof I elsewhere mention my selfe to have visited these Steams are apt actually to take fire The warmth of many Subterraneall Exhations I thinke may be made further probable by some other Observations For though these newly mentioned are not to be rejected and may be employed for want of better yet I have severall times questioned whether I ought to acquiesce in them alone For I do not thinke the easy inflammableness of Bodies to be alwaies a sure proofe of the actuall sensible warmth of the minute parts it consists of or may be reduced into For though Salt-peter be very inflammable yet being by a solution in fair water reduced to invisible Corpuscles it highly refrigerates that Liquor Nor have I observed its fumes when far from the Fire to have any heat sensible to our Touch. And the like may be said of the Exhalations of highly rectifi'd spirit of Wine which yet we know is itselfe totally inflammable Nay I know not whether for a Reason elsewhere declared copious Exhalations may not ascend from the lower parts of the Earth and yet be rather Cold then Hot. For in another Paper I mention a way by which I made a mixture that plentifully enough enitted Steams of whose being rather of a Cold then hot nature there was this probability that the mixture whence they ascended even whilsts its component Ingredients were briskly acting upon one another was not only sensibly but considerably Cold. One main thing therefore that induces me to assent to the Opinion whereto the former Instances do but incline me is That having purposely inquired of an observing man that frequented deep mines wherein he had a considerable share he answered me that he plainly observed the fumes that came out of the mouths of the deep pits to be actually and sensibly warm and that in a warm season of the year And Morinus above cited speaking of the deep Hungarian-mines makes it the first Epithite of the copious Exhalation that ascended from the bottom that it was hot And a few pages after he says that at the mouth of the Well the ascending Fumes were sensibly hot in Summer it selfe And the same Arguments that I have elsewhere given to shew that there are very hot places and as it were Aestuary in the Bowells of the Earth may serve to make it probable that the steams ascending thence may be actually warm That also in many places of the Earth where no Grooves are dugg and no visible Exhalations are taken notice of they may yet pervade the Soil and exercise some operations of warmth may be probable by this that the experienced Agricola himselfe reckons it among the signs of a latent minerall vein that the hoar-frost does not ly upon that tract of the Surface of the Earth under which a vein though perhaps very deep runs The like Directions I have known given by the skillfull in England for the Discovery of places that contain Coal-mines And I remember a near relation of mine shewed me a great scope of Land of his which though in an outward appearance likely to be as cold as any place thereabouts he affirm'd would not suffer Snow to ly upon it above a day or two in the midst of Winter The probability of which Relation was confirmed to me by