In a later work called “Mung-khi-py-than” will be found the following: “The soothsayers rub a needle with the magnet stone, so that it may mark the south; however, it declines constantly a little to the east. It does not indicate the south exactly. When this needle floats on the water it is much agitated. If the fingernails touch the upper edge of the basin in which it floats, they agitate it strongly; only it continues to slide and falls easily. It is preferable, in order to show its virtues in the best way, to suspend it as follows: Take a single filament from a piece of new cotton and attach it exactly to the middle of the needle by a bit of wax as large as a mustard seed. Hang it up in a place where there is no wind. Then the needle always shows the south; but among such needles there are some which, being rubbed, indicate the north. Our soothsayers have some which show the south and some which show the north. Of this property of the magnet to indicate the south, like that of the cypress to show the west, no one can tell the origin.” =A.D. 295–324.=--Koupho, Chinese physicist as well as writer, and one of the most celebrated men of his age, compares the attractive property of the magnet with that of amber animated by friction and heat. In his “Discourse on the Loadstone” he says: “The magnet attracts iron as amber draws mustard seeds. There is a breath of wind that promptly and mysteriously penetrates both bodies, uniting them imperceptibly with the rapidity of an arrow. It is incomprehensible.” REFERENCES.--Klaproth, “Boussole,” p. 125; Humboldt, “Cosmos,” 1848, Vol. V. p. 51; Libri, “Hist. des Mathém.,” Vol. I. p. 381, note 2. =A.D. 304.=--St. Elmo (St. Erasmus) Bishop of Formiæ, in ancient Italy, who suffered martyrdom about this date at Gæta, is the one after whom sailors in the Mediterranean first named the fires or flames which by many are believed to be of an electric nature and which appear during stormy weather, either at the yardarms, mastheads, in the rigging, or about the decks of a vessel. When two flames are seen together, they are called Castor and Pollux, “twin gods of the sea, guiding the mariner to port,” and are considered by seamen an indication of good luck and of fine weather; but when only one flame is visible it is called Helena, and is supposed to be an evil omen, the beacon of an avenging God luring the sailor to death. St. Elmo’s fire is also known to the Italians as the fire of _St. Peter_ and of _St. Nicholas_, to the Portuguese as _San Telmo_ and as _Corpos Santos_, and to the English sailors as _comazant_ or _corposant_.