[427] The fleur-de-lys placed at the north.
[428] That is, where it coincides with the meridian and begins to deviate or vary. Note, Milan edition.
[429] That is, varies east or west.
[430] Or of midday.
[431] I do not find any mention of the mediclino in any writer of the times near that of Pigafetta who have treated of the astrolabe, such as Regiomontanus, Appianus, Gimma Frisius, Danti, Clavius, etc.; but from what our author says here and elsewhere, it appears that the mediclino is that movable rule, fixed on the centre of the astrolabe, which turns round it, and is named sometimes albidade, or dioptron, or traguardo, or linea di fiducia. Note, Milan edition.
[432] Amoretti, in his introduction to this Treatise of Navigation, in the Milan edition, observes that Pigafetta was misled by a false theory when he supposes that there is in the heavens a point in repose to which the magnetic needle tends, but that the exact direction of the magnetic needle coincided, or at least approximated, to the meridian of the isle of Ferro, which is not now the case; and that in some other places the variations of the compass had been observed to correspond with that of the longitude. By the table of variations of the compass published by Lambert in the Ephemerides of Berlin (Astronomische Jahrbuch) for the year 1779, it is seen by an easy calculation that at the beginning of the sixteenth century the magnetic equator or zero of deviation was very near the isle of Tenerife. Now it is further off, and the distance increases. M. de Bougainville found there the deviation to the west to be 14 deg. 41 min.; and Staunton, the companion of Lord Macartney, found it to be 17 deg. 35 min.
[433] We have two astrolabes in our museum constructed with several plates: one is of brass, and another of card, for more easy manipulation. Note, Milan edition.
[434] “Traguardo,” level or traverser.
[435] “Rosa dei venti.”
[436] Or flag, as appears from the drawing.