Some Observations Relating to the Lyncurium of the Ancients; By William Watson, M. D. F. R. S.

XXXVII. Some Observations relating to the Lyncurium of the Ancients; by William Watson, M.D. F.R.S. Read Dec. 20, 1759. To determine the substance, denominated Lyncurium by the ancients, has been the occasion of much controversy among the more modern naturalists; some of whom, as late Dr. Woodward, believed it to be a species of the belemnites; others, as the late *M. Geoffroy*, considered it as amber. But it is evident from †Theophrastus's description of the Lyncurium, which is the most complete that has been handed down to us, that neither the one nor the other of the before-mentioned substances could be what he intended. His words are, Καὶ τὸ λυγκύριον. ὡς γὰρ εἰς τέττα γλύφειαι τα σφραγίδια. ὡς ἐπὶ δερεσάτην, καθάπερ λίθῳ. ἐλκει γὰρ ὁσπερ τὸ πλεκτρον. οἱ δὲ φάσιν ἐς μόνον καρφῇ ὑξελον, ἀλλὰ ὑ ἡλικῶν ὑ σίδηρον, ἐσαν ἡ λεπίδος. ὁσπερ ὑ Διοκλῆς ἐλέγει. "Ετι δὲ ἀπαράνι τε σφόδρα ὑ σύρρει... γινεται ὑ ἡ ἡ καλερτασία τις αὐλα σλειων. From hence we learn, that "the Lyncurium was a stone used for engraving seals on: that it was very hard: that it was endowed with an attracting power like amber: and that it was said, and by Diocles among the rest, to attract not only straws and small pieces of wood, but also copper and iron, if beaten very thin: that it was pellucid, and of a * Mater. Med. Vol. I. p. 165. de succino. Idem et Lyncurium quoque dicitur. † Theophrastus περὶ τῶν λίθων. "deep-" "deep-red colour; and required no small labour to polish it." The rest of Theophrastus's description is taken up with the fabulous account of the generation of this stone, "that it is formed by the urine of the lynx, which the animal, as soon as it parts with it, hides, and scrapes the earth together over it; and that the stones vary according to the sex and disposition of the animal." Dioscorides *, in his history of the Lyncurium, gives us only the fabulous history of its generation, before mentioned by Theophrastus; and subjoins, that it is called by some Ἀλεχίρον πλεροφόρον; that is, amber, which attracts feathers to it. Pliny, in his history †, disbelieves both the fabulous account of the generation of the Lyncurium, as well as its attractive quality, related both by Diocles and Theophrastus, and considers the whole as a falsity; though he is candid enough to confess, that neither himself, nor any one else in that age, had seen a gem of that appellation. Theophrastus, though more ancient, is, in most particulars, more to be depended upon than either Dioscorides or Pliny. He ought to be considered much more of an original author, and one who wrote from his own knowledge, than the others, who, valuable as they are, must be regarded, in most respects, as compilers. His account, then, of the appearance and properties of the Lyncurium must be considered, in order to examine, if any substance, known in our * Lib. II. cap. c. † Plin. Hist. lib. XXXVII. cap. iii. Ego falsum id totum arbitrator, nec visum in ævo nostro gemmam illam eà appellazione. Eee2 time, time, answers his description. But, first, it is plain that Dr. Woodward's hypothesis of the *belemnites* being the Lyncurium, was ill founded; inasmuch as the belemnites is neither pellucid, nor fit for engraving seals upon, on account of the friability of its texture; neither can it, by any management, be made to attract straws, chips of woods, or other light bodies. Nor is Geoffroy's opinion less liable to exception; as amber, though it has the attractive power mentioned by Theophrastus, yet it has by no means the firm texture requisite to have seals engraved upon it; neither is it so very hard, as is expressly said by this author concerning the Lyncurium, as to require great labour in polishing it. Add to these, that Theophrastus has given a particular account of the history and properties of amber * separately, in the before-mentioned work. If, after what has been said, I may be permitted to give my thoughts concerning the *Lyncurium* of the ancients, I make no scruple to think it to be exceedingly probable, that what we now call the *Tourmaline* was the *Lyncurium* of Theophrastus, as it agrees with that author's description in all its sensible qualities; to wit, that it is a very hard pellucid stone, of a deep-red colour; that it is very proper to engrave seals upon; that it attracts, like amber, not only straws and light pieces of wood, but filings of iron and brass, as has been lately evinced by many experiments. And what will give some weight to this --- * Vide Theophrast. περὶ τῶν λίθων. νγ. Καὶ τὸ ἑλεκτρον λίθος, ὡς γὰρ ὀρυζον τὸ περὶ Λιγυστικόν, ὡς τε ὁμάδι τὰ ἐλκεῖν δύναμις ἀπολαβὼν.* opi- opinion is, that this stone, though not much attended to by us till very lately, is very common in several parts of the East Indies, and more particularly in the island of Ceylon, where it is called by the natives Tournamal. The first account which we have had, of late years at least, of this extraordinary stone, was in the History of the Royal Academy of Sciences of Paris, for the year 1717; where we are told, that Mr. Lemery exhibited a stone, which, he said, was not common, and came from Ceylon. This stone attracted and repelled little light bodies, such as ashes, filings of iron, bits of paper, and such like. The publisher of that history then proceeds to give some reasons for these phenomena. Linnæus, in his preface to the Flora Zeylanica, mentions this stone under the name of lapis electricus; and takes notice of M. Lemery's experiments before-mentioned. Notwithstanding this, no further mention was made of this stone, and its effects, till very lately. The duke de Noya, in his letter to M. de Buffon, which was presented to the Royal Society a few months ago, informs us, that when at Naples in the year 1743, the late count Pichetti, secretary to the king, assured him, that, during his stay at Constantinople, he had seen a small stone, called a tourmaline, which attracted and repelled ashes. This account the duke de Noya had quite forgot; but, being last year in Holland, he saw and purchased two of these stones, which are there called aschentrikker. The making experiments with these called to his remembrance what formerly had been told him by count Pichetti. With these stones he made, in company with Mes- sieurs Daubenton and Adanson, a great number of experiments, of which the duke has favoured the public with a particular account. In the year 1757, there were two accounts published upon this subject: the one is a memoir of M. Æpinus, read to the Royal Academy at Berlin, intituled, *De quibusdam experimentis electricis notabilioribus*. The other is a treatise in quarto, printed at Rostock, intituled, *Disputatio de electricitatibus contrariis*. Auctore Joanne Carolo Wilke. Since which time, Dr. Heberden, who is ever desirous of extending the bounds of science, having procured some of these stones from Holland, a great number and variety of experiments with them have been made here, particularly by the ingenious Mr. Wilson; an account of which he has very lately communicated to the Royal Society. XXXVIII. An Attempt to account for the regular diurnal Variation of the horizontal magnetic Needle; and also for its irregular Variation at the Time of an Aurora Borealis: By John Canton, M.A. and F.R.S. Read Dec. 13, 1759. THE late celebrated Mr. George Graham made a great number of observations on the diurnal variation of the magnetic needle, in the years 1722 and 1723; but declared himself ignorant of the cause of that variation, in No. 383 of the Philosophical Transactions, where many of those observations are to be found. About