Flavius Blondus, whom Gilbert cites, gives the following reference, in which Gioia's name is not mentioned, in the section upon Campania Felix of his Italy (Blondi Flavii Forlinensis ... Italia Illustrata, Basiliæ, 1531, p. 420).
"Sed fama est qua Amalphitanos audiuimus gloriari, magnetis usum, cuius adminiculo nauigantes ad arcton diriguntur, Amalphi suisse inuentum, quicquid uero habeat in ea re ueritas, certû est id noctu nauigandi auxilium priscis omnino suisse incognitum."
There is a further reference to the alleged Amalphian in Caelius Calcagninus De re nautica commentatio. (See Thesaurus Græcarum Antiquitatum, 1697, vol. xi., p. 761.) On the other hand Baptista Porta, who wrote in Naples in 1558 (Magia Naturalis) distinctly sets aside the claim as baseless.
William Barlowe, in The Navigators Supply (1597, p. A3), says: "Who was the first inuentor of this Instrument miraculous, and endued, as it were, with life, can hardly be found. The lame tale of one Flauius at Amelphis, in the kingdome of Naples, for to haue deuised it, is of very slender probabilitie. Pandulph Collenutius writing the Neapolitane historie telleth vs, that they of Amelphis say, it is a common opinion there, that it was first found out among them. But Polidore Virgil, who searched most diligently for the Inuentors of things, could neuer heare of this opinion (yet himselfe being an Italian) and as he confesseth in the later ende of his third booke de inventoribus rerum, could neuer vnderstand anything concerning the first inuention of this instrument."
According to Park Benjamin (Intellectual Rise in Electricity, p. 146) the use of the pivotted compass arose and spread not from Amalfi at the hands of Italians in the fourteenth century, but from Wisbuy, at the hands of the Finns, in the middle of the twelfth century.
Hakewill (An Apologie or Declaration of the Power and Providence of God, London, 1673, pp. 284-285) says:
"But Blondus, who is therein followed by Pancirollus, both Italians, will not haue Italy loose the praise thereof, telling vs that about 300 yeares agoe it was found out at Malphis or Melphis, a Citty in the Kingdome of Naples in the Province of Campania, now called Terra di Lovorador. But for the Author of it, the one names him not, and the other assures vs, he is not knowne: yet Salmuth out of Ciezus & Gomara confidently christens him with the name of Flavius, and so doth Du Bartas in those excellent verses of his touching this subject.
"'W' are not to Ceres so much bound for bread,
Neither to Bacchus for his clusters red,