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.

CHAP. XV. Directions for Observing the Stars.

SUppose I am at Sea in a Ship, and I observe the bright Star in the left Foot of Orion Rigel, upon the Meridian, and find his Altitude 44 deg. 32 min. his Declination is 8 deg. 37 min. North; The Latitude is required, the Ship is in.

	deg.	min.
The Meridian Altitude	44	32
The Declination North	08	37 substract.
The Complement of the Latitude	35	55
	90	00
The Latitude the Ship is in	54	05

Suppose I am at Sea, and I observe the South Balance of Libra, and by Observati∣on of the Star upon the Meridian, I find his Altitude 39 deg. 27 min. and his Declination South 14 deg. 27 min. I require the Latitude I am in.

	deg.	min.
The Meridian Altitude	39	27
The Declination of the Star	14	37 South.
The Height of the Aequinoctial	54	04
	90	00
The Latitude the Ship is in	35	56

I have furnished the Practitioner with all useful and needful Examples, which I thought necessary for direction, which explains the following Tables, and shews the most easie and perfect way of Observation, and how to work them on either side the Aequator. Others I confess have been larger, but none more plain: for he that can∣not understand these Rules and Directions, is not fit to be a Mate of any Ship or Vessel, nor fit to be ranked among the Ingenious Mariners.