The mariners magazine, or, Sturmy's mathematical and practical arts containing the description and use of the scale of scales, it being a mathematical ruler, that resolves most mathematical conclusions, and likewise the making and use of the crostaff, quadrant, and the quadrat, nocturnals, and other most useful instruments for all artists and navigators : the art of navigation, resolved geometrically, instrumentally, and by calculation, and by that late excellent invention of logarithms, in the three principal kinds of sailing : with new tables of the longitude and latitude of the most eminent places ... : together with a discourse of the practick part of navigation ..., a new way of surveying land ..., the art of gauging all sorts of vessels ..., the art of dialling by a gnomical scale ... : whereunto is annexed, an abridgment of the penalties and forfeitures, by acts of parliaments appointed, relating to the customs and navigation : also a compendium of fortification, both geometrically and instrumentally / by Capt. Samuel Sturmy.

To Work your Observation.

IF the Sun hath North Declination, and be on the Meridian to the Southwards of you, then you must substract the Sun's Declination from your Meridian Altitude, and that Remainder is the Height of the Aequinoctial, or the Complement of the La∣titude North. But if the Sun hath South Declination, you must add the Sun's De∣clination to your Meridian Altitude, and the Sum is the Height of the Aequator, or the Complement of the Latitude North. If the Sun hath North Declination, and be on the Meridian to the Northwards, then add the Sun's Declination to his Meridian Al∣titude, and the Sum is the Height of the Aequator, or the Complement of the Latitude South, if the said Sum doth not exceed 90 deg. but if it doth exceed 90 deg. you must substract 90 deg. from the said Sum, and the Remainder is your Latitude North.

If the Sun hath South Declination, and be to the Northwards at Noon, you must then substract the Sun's Declination from his Meridian Altitude, and the Remainder is the Complement of your Latitude South. When the Sun hath no Declination, then the Meridian-Altitude is the Complement of the Latitude. If the Sun be in the Ze∣nith, and if at the same time the Sun hath no Declination, then you are under the Aequinoctial.

But if the Sun hath North Declination, and in the Zenith, then look how many Degrees and Minutes the Declination is, and that is the Latitude you be in North.

But if your Declination be South, then you are in South Latitude. If you observe the Sun or Star upon the Meridian beneath the Pole, then add your Meridian Alti∣tude to the Complement of the Sun or Stars Declination, and the Sum is the Height of the Pole.