[90] [Lacmus or litmus is now prepared from _Lecanora tartarea_, the famous _Cudbear_, so called after a Mr. Cuthbert, who first brought it into use. It is imported largely from Norway, where it grows more abundantly than with us; yet in the Highland districts many an industrious peasant gets a living by scraping off this lichen with an iron hoop, and sending it to the Glasgow market.] [91] Linn. Mantissa Plantarum, i. p. 132. [92] See Wallis’s Natural History and Antiquities of Northumberland, 1769, 2 vols. 4to, i. p. 279. MAGNETIC CURES. The external use of the magnet, to cure the tooth-ache and other disorders, is a remedy brought into fashion in modern times, but not a new discovery, as supposed by Lessing, who ascribes it to Paracelsus[93]. It was known to Aëtius, who lived so early as the year 500. That author says, “We are assured that those who are troubled with the gout in their hands or their feet, or with convulsions, find relief when they hold a magnet in their hand[94].” He does not however give any proof of this from his own experience: and perhaps he doubted the truth of it. The above passage contains the oldest account known at present respecting this virtue; for the more ancient writers speak only of the internal use of the magnet. It is evident therefore that this cure has not been discovered in later times, but that it has been preserved by the old physicians copying it from each other into their works. In like manner, many things are mentioned in the Materia Medica which were used or proposed by the ancients, but into the properties of which they never made sufficient inquiry. Paracelsus recommended the magnet in a number of diseases, as fluxes, hæmorrhages, &c. Marcellus, who lived in the fifteenth century, assures us that it cures the tooth-ache[95]. The same virtue is ascribed to it by Leonard Camillus[96], who lived in the sixteenth century: and Wecker[97], who was nearly co-temporary, says that the magnet when applied to the head, cures the head-ache; and adds that Holler had taken this cure from the works of the ancients[98]. We read also in Porta[99], that it was recommended for the head-ache; and in Kircher[100], that it was worn about the neck as a preventive against convulsions, and affections of the nerves. About the end of the 17th century magnetic tooth-picks and ear-pickers were made, and extolled as a secret preventive against pains in the teeth, eyes and ears[101].