"Subsequently the instrument was improved by degrees, till it assumed the shape of a box, containing a needle moving freely on a metal point, and covered by a compass-rose." It is here probably that the share of Amalfi is to be found,[291] and it may have been Flavio Gioja, or some other citizen of the oldest commercial republic of Italy, who first fitted the magnet into the box, and connected it with the compass-card, thus making it generally and easily available.[292] [Footnote 291: "Prima dedit nautis usum magnetis Amalphis."] [Footnote 292: Such a compass-box is figured on the margins of some MSS. of Dati's _Sphera_ of the early fifteenth century. See Nordenskjöld _Periplus_, p. 45.] This it certainly was not in Latini's time. "No mariner could use it (the polarized magnet), nor would sailors venture themselves to sea ... with an instrument so like one of infernal make." In the latter part of the thirteenth century, and not before, its use seems to have crept in among Mediterranean pilots and captains, and in the course of the fourteenth century it was almost universally accepted. A mistake has been made on one point. The first scientific (or portolano) type of map is generally associated with the first scientific use of the magnet; but portolani began while men had not advanced beyond the use of the primitive water-compass above described; and "accurate determination by means of this" must have been very difficult on a tossing sea. "A comparison of the contours of the Mediterranean, according to various portolanos, with a modern chart, shows that the normal portolano contained no mistake due to the misdirection of the compass."[293] Nor do the earliest portolani contain any compass-roses or wind-roses. Gradually these were introduced into the new charts,_ e.g._, they are found in the Catalan Atlas of 1375, in the Pinelli of 1384, and in many fifteenth-century portolani; but not till the sixteenth century do we have a number of these roses drawn on the same map-sheet. [Footnote 293: _Periplus_, p. 47.] The use of the quadrant by Prince Henry and his sailors is expressly mentioned by Diego Gomez; but neither in this case, nor in that of the compass, are we warranted in assuming (as some authorities have done) that to the Infant is due the first use of astronomical instruments at sea. C. RAYMOND BEAZLEY. 13, THE PARAGON, BLACKHEATH. _March 27th, 1899._ FACSIMILE OF PRINCE HENRY'S INITIAL SIGNATURE. [I. D. A. = Iffante Dom Anrique.] [Illustration: autograph] [Illustration: map of western Africa HAKLUYT. S. I. v. C] AZURARA'S CHRONICLE OF THE DISCOVERY AND CONQUEST OF GUINEA. CHAPTER XLI. How they took the ten Moors.