A regiment for the sea conteyning most profitable rules, mathematical experiences, and perfect knovvledge of nauigation, for all coastes and countreys: most needefull and necessarie for all seafaring men and trauellers, as pilotes, mariners, marchants. [et] c. Exactly deuised and made by VVilliam Bourne.

The .8. Chapter sheweth you how to handle the declination of the Sunne, when you are betweene the Equinoctiall and the Sunne: that is to say, the Sunne being to the Southwards or Northwards of you and the Equinoctial, or vnder the Equi∣noctiall: the heigth of the Sunne being truely knowen or taken.

NOw furthermore if you be vnto the South parts neare vnto the equinoctiall, so that the Sunne haue any great declination either to the Southwards or y^e Northwards, you being between the equinoctial and the Sunne, whē you haue taken the true heigth of the Sun with y^e Astrolobe, to know the heigth of any of the .2. poles do this: séeke the declination of the Sun for that day with the degrées & minuts, the decli∣natiō being known & the heigth of the Sunne in like maner, then adde y^e declinatiō of the Sun vnto the heigth thereof, & it will exceede or be more than .90. degrées, then againe looke how many degrees it is more thā .90. with degrées & minuts, that shal be the true heigth of the pole towards that side that the Sun is: bycause y^e Equinoctial is y^e number of degrées a∣boue .90. (which is your Zenith) to the contrary part frō the Sunwards. For (as I haue said in y^e chapter going before & is general for euer) looke what heigth soeuer y^e Equinoctial be frō y^e horizō, that is the true distance betwéene y^e Zenith and the pole: in like maner looke what distance is betwéene the Equinoctial & the Zenith, y^e same is the true distāce betwen the horizon & the pole, that is to say, the pole is so many de∣grées in altitude aboue y^e horizō. As it is a cōmon saying (in knowing how farre we be vnto the Southwards or North∣wards) y^t the pole artick is so many degrées in altitude, or (as som wil say) that we are in so many degrées in Latitude: the question is all one in effect, although the one be called Alti∣tude or heigthe, and the other Latitude or widenesse, yet it hathe one signification: for as when you say altitude or

heigth of the Pole, you meane the Pole is raysed so many degrees aboue the Horizon. So likewise when you say Lati∣tude, you mean you be so many degrees in widenesse frō the Equinoctiall: for that your Zenith or verticall pointe is so many degrées frō the Equinoct. Moreouer if you chaunce to be right vnder y^e Equinoctial, as you cānot say that you haue any Latitude, so likewise cannot you say that you haue any Altitude, for that the two Poles be then iust with your Ho∣rizon, and in like maner the Equinoctiall is your Zenith or Verticall poynte. But when you will take the heigth of the Sunne with your Astrolobe, then looke what declination the Sunne hath, either to the Southwardes or Northwardes. Then put the declination of the Sunne vnto the heigthe of the same, and the number will be iust .90. degrées: if it lac∣keth any thing of .90. degrées, then it signifieth that the E∣quinoctiall lacketh so much of the Zenith, and so muche iust shal the pole be aboue y^e Horizon towards that part that you be in from the Sunne wardes. But contrarywise, if it dothe excéede or be any thing more than .90. degrées, then (as afore is declared) it signifieth that the Equinoctiall is as much as that number (both in degrées and minutes.) On the contra∣ry side, from the Sunne wardes, that is to say, your Zenithe shal be betwéene the Sunne and the Equinoctial, & the Pole shall be so many degrees or minutes aboue the Horizon, as is the distaunce betwéene the Zenith and the Equinoctiall, towardes that part or side that the Sunne is on. Wherefore I do think it necessarie to giue certaine ensamples (and first take this for an ensample.) Admit I doe take the heigth of the Sunne vnto the Northwards .80. degrées aboue the Ho∣rizon, and the Sunne hathe declination vnto the North∣wardes .20. degrées, to which I adde or put the heigth, that is to say .80. degrées (being the heigth of the Sunne) and .20. de∣grees (being the declination of the Sunne) doe make .100. frō which I pull .90. away (which is my Zenith) and so ther re∣mayneth .10. degrées. Wherefore you may conclude that the

Equinoctiall is .10. degrées to the South parte of youre Ze∣nith, and the Sunne to be .10. degrées to the North parte of your Zenith, so that the North Pole is .10. degrées aboue the Horizon, as by this example it is declared.

[illustration]

And for the second ensample, admit I take the Sunne vn∣to the Northwardes .75. degrees and .20. minutes aboue the Horizon, the Sunne hauing North declination .14. degrées 40. minutes, I then do adde or put .14. degrées .40. minutes vnto .75. degrées .20. minuts, and those .2. ioyned togither ma∣keth .9••. degrées, whereof you may conclude that the Equi∣noctiall is your Zenith, and then the .2. Poles be with your Horizon, as by this example it doth appeare.

[illustration]

And now followeth the .3. ensample. I admit the Sunne be taken with the Astrolobe .81. degrees and .15. minutes a∣boue the horizon, and the same hathe South declination .22.

degrées .35. minutes, wherefore I do adde or put togither .81. degrées and .15. minutes (being the heigth of the Sunne) and 22. degrées .35. minutes (being the declination) and that ma∣keth .103. degrees .50. minutes: from which I take away .90. degrées (which is my Zenith) so that there remayneth .13. de∣grees .50. minutes: so that you may safely conclude that the Equinoctiall is .13. degrées .50. minutes vnto the North parts of the Zenith, and then it must néedes follow that the South pole is .13. degrees .50. minuts aboue the Horizon, as by thys ensample it is declared.

[illustration]

Notes

• A thing to be noted.
• Altitude or Latitude is all one que∣stion in ef∣fect.
• Being vn∣der the E∣quinoctiall you haue neither La∣titude nor altitude, for that the E∣quinoctiall is your Ze∣nith and the Poles your Horizon.
• Of your ze∣nith being betweene y^e Equinocti∣all and the Sunne.
• An ensāple.
• An ensāple where the pole is .10. degrees a∣boue the Horizon.
• An ensāple.