A Discourse concerning the Sepulchral Lamps of the Ancients, Shewing the Possibility of Their being Made Divers Waies, Read before the Philosophical Society of Oxford, May the 7. 1684. by Robert Plot LL. D. Director of Experiments to the Said Society

A discourse concerning the Sepulchral Lamps of the Ancients, shewing the possibility of their being made divers waies, read before the Philosophical Society of Oxford, May the 7. 1684. by Robert Plot LL.D. Director of Experiments to the said Society. Mr. President and Gentlemen, YOU may well remember that at the last meeting, I shewed you that the downy part of the Mineral call'd Linum Asbestinum, Earth-flax, or Salamanders Wooll, would make, and do the office of a Weik tolerably well; it having burnt from about nine in the morning (being still supplyed with Oyl) till about four in the afternoon (about what time that Session broke up) without sensible diminution: yet it was objected that upon other trials a friability had been found in it, which argued some sort of consumption; and that allowing it invincible in the fire, yet there might be some danger of its being clog'd by the impurities of the best Oyl that could be got, or any way prepared. To the first of which Objections it was then answer'd, that there was no such absolute necessity of making use of that Wooll, but that another Weik might be contrived, against which that exception could not lye; such as a Metallin Wire, especially of the best refined Gold (whose prerogative it is, not to be diminish't by fire) that will lick up Oyl as well as any other Weik, and so make a perpetual flame, provided it be supplyed with a perpetual Oyl: this I must confess I have often heard asserted, but never applied my self to the trial of the Experiment, till I received your commands to do it the last week; in execution whereof I found that in a Faggot of Wire made made of anneal'd Iron, of a suitable bigness for a Weik, it would not succeed by any manner of means I could readily think of; nor have I much reason to think it will, after the most mature deliberation, either in Wire or Silver or Gold (though I dare not pronounce the contrary till trial has been made) the nature of them all seeming not much different, as to this particular. If therefore it be necessary, that we must have a perpetual Weik for the making such perpetual Sepulchral Lamps, as were used by the Ancients, I think we must stick to the first kind, made of Linum Asbestinum, or Salamanders-wool; which if it any way can be supplied with a perpetual Oyl (as I shall presently shew you) I hope you will not judge me far from effecting the matter. Now that there may be such a Bitumen or inexhaustible Oyl, I shall not need to trouble you with the Testimonies of old Authors, or carry you into Italy, or other foreign parts: for will you but allow me an inconsumable Weik, I will carry you no further than Pitchford in Shropshire, where there is a Naphta or liquid bitumen (a Specimen whereof I have here to shew you) that constantly issues forth with a Spring there, and floats upon the Water: this I would have separated before it joynes with the water into a ductus of its own, and so conveyed to the place, thought most convenient for such a Lamp, into which it should as perpetually distill, as it does now into the fountain; which I doubt not but you will allow may be done, without any great matter of difficulty: and if so, we have an Oyl, as everlasting as our Weik: nor need we to fear any extinction if inclosed in a Tomb or Vault underground, in never so damp or moist a place; it being the Characteristic of a bitumen, to burn best where there is moisture, as is evident upon diffusion of water upon Sea-coal. And this is one way I have thought of, that such a perpetual Sepulchral Lamp might possibly be contrived. But if you will be too strict with me, as not to allow this this to be a perpetual Weik, or that 'tis probable one should be made any other way; as unlikely may it seem to most (that I say not to this Society) that there was ever any such thing as a perpetual Lamp; notwithstanding the Testimonies of St. Austin, Plutarch, Pliny, Ludovicus Vives, Baptista Porta, Lacerus, Pancirollus, and divers others, whereof some are said to have burnt a 1000, some 1500 years. But I dare not think so many, and so very good Authors, have all imposed upon us, or that 'tis almost possible that so many notable instances as are brought for them, should all be false. Much rather therefore shall I determine (than wholly explode the thing) that the liquor of these Lamps did burn without any Snuff or Weik at all, as we see Camphore and most bitumens will, it not being express't (that I remember) scarce in any of the relations of these Lamps, that they were found with any Weiks, whence both the inconveniences above mention'd attending a Weik, ipso facto cease. It only therefore remaining that we find out an inexhaustible Oyl, which conveyed to a fit vessel might cause such a Lamp; why may not our bitumen at Pitchford serve the turn? which no question will burn without a Weik, as well as any other liquid bitumen: for I begged not above in this instance the favour of a Weik out of necessity, but that I was willing to shew the probability of its being done as many waies as I could. All the objection I can foresee that is likely to obtain advantage against such an Experiment, is that such a Lamp as this, would as likely burn in the open Air, as in an inclosed damp Vault, whereas the Lamps of the Ancients did nourish their flame best, where there was most want of Air, only in close Vaults and Tombs, and were presently extinguish't upon the least immersion of External Air, these being qualities necessary, and almost alwaies asserted as concomitants of the Ancient Sepulchral Lamps. To which I answer first, that some of the Lamps of the Ancients, cients, did as well burn in the open Air, as in close damp Vaults, as that mention'd by St. Austin in his book de Civitatis Dei, which hung in the Temple of Venus alwayes exposed to the open weather, yet was never either consumed or extinguish't. The Lamp also found in the Tomb of Pallas the Arcadian, slain by Turnus in the Trojan War, was of this kind, which remain'd burning after it was taken forth, notwithstanding either Wind or Water, with which some did endeavor to quench it. Now admitting our Lamp at Pitchford should thus burn indifferently under both circumstances, what are we the worse? Since I never heard that the Lamp mention'd by St. Austin, or of Pallas, were ever the less esteemed or admired, because they could not be extinguish't by the open Air, as most of the rest have been said to be. But if any body be so wise that He must have an Oyl in all particulars answerable to that other sort of the Ancients, that burns best where there is want of Air, and is destroyed by its admission: let Him but go with me into Flintshire to the Coale-works of Sr. Roger Mostyn of Mostyn in that County, and He may have satisfaction; where the Miners when they have dugg so deep, that they begin to perceive a want of Air, find a bleuish flame to begin to kindle of it self in the fissures of the Coal (at which, by way of sport, they sometimes light their Candles) which blazes, and moves up and down continually, and sometimes shines too upon the surface of the water in the bottom of the Pits, shewing all the colours of the Rainbow: which yet upon drawing up of the water that annoyes the works, and thereby stirring the Air, will leave burning; but as they sink lower, and are more remote from the day or superterraneous Air, still increases upon them: whence it plainly appears that this is a sort of fire that so little requires Air for the maintenance of it; that it burns best when there is least Air, and is extinguish't when disturb'd by the motion of it; as the ancient Lamps are said to be, upon the immersion of external Air. This therefore must be the fire fittest for this sort of Sepulchral Lamps (for it seems they were not all alike) for the account whereof, we all stand obliged to an eminent member of this Society, the learned Dr. Bathurst Dean of Wells, and President of Trinity College Oxon. By whose care the relation of the strange Phænomena of this sort of fire, stand register'd in the Philosophical Transactions, Numb. 136. to all posterity. Since which it has also been taken notice of, in the Coal-works of Somersetshire, by the ingenious Mr. Beaumont; and by Mr. George Sinclair in the Coal-works of Scotland. This I doubt not but you will readily allow me to be as probable a material for the Oyl of this second sort of perpetual Lamps; as that of Pitchford was, for the former: But how this, or that, shall be so menaged, as to be put into a Lamp, and this Lamp perpetually supplyed, and placed wherever it shall be desired; as it seems the Lamps of the Ancients might, this fire being sometimes found in little Pots, Glasses or Urnes, without any such ductus to them as we required at Pitchford, or might do here; is a difficulty perhaps not easily conquered. To which I must confess that I have only this to say, that unless there can be a preparation Chymically made out of these bitumnious materials, which thus naturally take fire of themselves, or preserve it without a Weik; a small quantity whereof shall maintain so tenuous a flame as that there shall be no considerable consumption of the matter in many years (such as the flame over the Well; and Earth about it, in one Mr. Hawkley's ground in Lancashire, that (like the fire of Plato) only shines and does not burn) we must be contented to be tyed to the places where these materials are. But if we can be content to quit these materials, and to think that these Lamps (as many have done) did not shine or burn for all the time they were inclosed in these Tombs, but were only inkindled inkindled by the admission of Air when open'd: I have thought of a way not at all liable to any of the defects or inconveniencies, of the two former waies; whereby a Glass of liquor inclosed in another (like the Urns of Olybius) upon immission of external Air, shall certainly shine, though it did not so before. And 'tis this: take a small Phial, into which put a little of the liquid Phosphorus (which you all know, if the Phial be stoppt, shines not at all, the external Air being excluded from it) include this in another Glass, as suppose the recipient of an Air-pump, out of which if the pump be stanch, so that the Air may be well exhausted, the solid Phosphorus itself, will leave off shining in ten hours time, though in the Summer-quarter; and the liquid in fewer, so that it shall shine no more, than when the bottle containing it, is stoppt with a Cork; and both of them will be extinguish proportionably in a yet less time, if the Air be taken from them in the Winter season; as has been frequently experimented by my worthy Friend Frederick Slare M.D. and shall again be repeated as soon as I can procure a nice Air-pump fit for the purpose. Now let such an exhausted Recipient with the included Phosphorus, be placed in a Tomb or Vault which are commonly dark, and if ever found, and the outer Glass broken (as usually such things are, by ignorant Men employed in digging) possibly there will appear, upon immission of the Air, as good a perpetual Lamp, as some that have been found in the Sepulchres of the Ancients, tho in all probability of a different kind, from all, or most of them. A Let-