The decades of the newe worlde or west India conteynyng the nauigations and conquestes of the Spanyardes, with the particular description of the moste ryche and large landes and ilandes lately founde in the west ocean perteynyng to the inheritaunce of the kinges of Spayne. ... Wrytten in the Latine tounge by Peter Martyr of Angleria, and translated into Englysshe by Rycharde Eden.

¶ The maner of fyndynge the Longitude of regions by dyuers wayes after the description of Gemma Phrysius.

PErceauynge what contention is and longe hath byn not only amonge the pylottes that by tra∣uaylynge the sea haue obserued the starres, but also amonge sum men that are skylfull in ma∣thematicall sciecens, wherof many affirme that the longitude (that is to meane, the course from the East to the Weste) can not be perfectely knowen, I haue thowght good for the better satisfying of such as desire to haue sum knowleage hereof, to interprete such demonstra∣tions as I haue redde of the declarynge of the same in Gem∣ma Phrysius, who as touchynge this matter hath added to thinuentions of other, a more certeyne way of his owr diuise wherby (as he sayth) he can fynde the longitude of regions although he were dryuen owt of the way a thousande myles into places vnto hym vtterlye vnknowen and of vnknowen distance. He wryteth therfore as foloweth.

When yow haue founde the place of the mone,* 1.1 yow ought to consyder the houre when she occupyed that place. Then ey∣ther by the Ephimerides or by the tables of Alphonsus yowe owght to knowe in what houre the moone entereth into the same signe of the Zodiake in an other region or towne whose longitude is well knowen. Then reducynge the houres to xxiiii. the lesse number of houres is to be deducted out of the greater number. Then the remanent of the houres & mynutes is to be brought to degres in this maner. Multiplie the hours by .xv. and diuide the minutes of the houres by foure: so shall appere the degrees of the Equinoctial conteyned betwene two

meridians. And if after this diuision there r••mayne any mi∣nutes, multiplie them also by .xv. and therby shalbe know••n the minutes of degrees. Adde th••s di••ference of longitu••e founde to the longitude of the region knowen if the houres of that place bee more in number: or take awaye from the same longitude if they be lesse: So shall yowe in fin•• gather the longitude of the place vnknowen from the Ilandes of Cana∣rie.* 1.2 But the same is more easely and redely found geome∣trically by the globes by this meanes. Set directly vnder the meridian, the place whose longitude is knowen in the globe.* 1.3 Then directe the poynte or style that moueth abowt the pole, to the houre in the whiche the moone occupyeth the place assigned in that region. Then turne the globe vntyll the style that sheweth the houre, be coomme to the houre in the whi∣che yowesowght the vnknowen place of the moone. And so shall the degrees of the Equinoctiall distaunte or diuy∣ded frome the moueable meridian, declare the longitude of the region which yow seeke. Neuerthelesse, the more certeine way wherby the differences of longitudes may bee founde, is by sum one thynge that in one moment appeareth in all regi∣ons, as by the eclypses of the moone.* 1.4 For the dyuers houres beinge knowen in the whiche the sayd eclypses chaunce in dy¦uers regions, the longitudo maye thus aswell be knowen by geometrie and arithmetike, as it is founde by the rule here be¦fore. But forasmuch as this doth neyther appere at al tymes nor to all men, and the other way is sumwhat difficult, ney∣ther at al tymes redy by reason of the cōiunctions of the mone and furthermore also sumtymes vncerteyne and varying sum what from the truth for the dyuers aspectes and l••titud••s of the mone, it so chaunceth hereby that wee haue eyther no lon¦gitudes or the same very vncerteyne of many regions, and es∣pecially of those which the Spanyardes haue of late discoue∣red. For no certentie doubtlesse can be knowen by such com∣mensurations as are made in the wanderynge turnynges and wyndynges of such vyages, as Ptolome affirmeth in the first booke of his Cosmographie. I wyll therfore adde herevnto sum thynge of myne owne inuention whereby by an easy way and at all tymes the longitudes of regions may bee founde in all vyages and nauigations.

Notes

• * 1.1

  By the mone.
• * 1.2

  The Ilandes of Canarie.
• * 1.3

  howe to fynd the longitude by the globe
• * 1.4

  The Eclipses of the moone.