M. Blundevile his exercises containing sixe treatises, the titles wherof are set down in the next printed page: which treatises are verie necessarie to be read and learned of all yoong gentlemen that haue not bene exercised in such disciplines, and yet are desirous to haue knowledge as well in cosmographie, astronomie, and geographie, as also in the arte of navigation ... To the furtherance of which arte of navigation, the said M. Blundevile speciallie wrote the said treatises and of meere good will doth dedicate the same to all the young gentlemen of this realme.

How to know the Latitude of any place, aswell in the day as in the night. Chap. 8.

BEcause the Latitude of any place is more easie to be found (as most men thinke) then the Lon∣gitude, I will first treat of Latitude. The Lati∣tude thē is to be knowne by the Astrolabe, Qua∣drant, Crossestaffe, and by such like Mathema∣ticall instruments, & that diuerse wayes where∣of the most easie is thus: first with your Astro∣labe or Quadrant, or any such like instrument, take the height of the sunne right at noone, when the sunne is in the first point of A∣ries or of Libra, which height if you subtract from 90. that which remaineth is the true Latitude of that place. But if you would knowe the Latitude at any other day or time of the yeare, then after that you haue taken the height of the sunne at noone, other∣wise called the Meridian altitude, you must first learne to knowe the true degrée of the sunnes declination by the Table of the decli∣nations before set downe, together with the vse thereof in the 13. Chap. of the first booke, or by some other Table more lately calcu∣lated, and if such declination be Northernly, then you must subtract that from the foresaid Altitude or height: but if the declination be Southernly, thē you must adde the same vnto the foresaid height, and by such subtraction or addition, you shall haue the height of the Equinoctial aboue your Horizon, which being subtracted from 90. that which remaineth is the true Latitude of that place: and

to be sure in taking the Meridian altitude, it shall be néedefull to take it diuerse times one after another, with some little pawse be∣twixt, to sée whether it increaseth or decreaseth, for if it doth in∣crease, then it is not yet full noone, but if it decreaseth then it is past noone. This last way of finding out the Latitude, is, and hath béene most commonly taught, as well by the auncient, as moderne writers, as a most sure and readie way of finding the Latitude of any place.

What if the sunne doe not shine at noone, nor perhaps all that day?

Then you must tarrie vntill night that some starre appeare, which you perfectly knowe, and such a one as both riseth and setteth. And hauing taken the Meridian altitude of that starre with your Astrolabe or Quadrant, you must learne what decli∣nation he hath, and whether it be Northerne or Southerne. For if the starre hath North declination, then you must subtract his declination from his Meridian altitude, and the remainder shall be the Altitude of the Equinoctiall, which being taken out of nintie, shall be the Latitude of the place, or eleuation of the pole: but if the declination of the starre be Southernly, then you must adde his declination to his Meridian altitude, and that summe shall be the Altitude of the Equinoctiall, which being taken out of 90. the remainder shall be the eleuation of the Pole. As for example, supposing that you knowe the starre called Arcturus, or Bubulcus, and that you finde his Meridian alti∣tude by your Astrolabe or Quadrant to be 59. degrées 30. minutes and also that you haue learned by some Table, that his declina∣tion to the Northwarde is 21. degrées 30. minutes: here by ta∣king his saide declination because it is Northernly, out of his Meridian altitude, you finde the remainder to be 38. degrées which is the Altitude of the Equinoctiall, which béeing taken from 90. the remainder wilbe 52. degrées, which is the Latitude of the place whereas you made your obseruation, and this is a farre more readie waye then to waite all night to take the Me∣ridian altitude, and also the depression of such a starre as ne∣uer setteth, which is séeledome done in one selfe night. And therefore I would wishe all Mariners to acquaint themselues with manie starres that doe both rise and set, and so shall they

be sure to finde one such starre or other, to be at his Meridian altitude at any houre of the night that they desire, if the starres doe shewe.