For example, in these two Haemisphaeres, the longitude of the whole earth is from (_C_) to (_A_) and (_B_) in the AEquator. The latitud is from (_N_) to (_S_), and from (_Q_) to (_P_) the North and South poles, and this reckoned in any meridian. The first meridian is (_ANBS_) which goes by the Canary Ilands, the AEquinoctiall is (_ABCA_). Now I haue a Citty giuen so. (_D_) I would know in what longitude and latitude it is. For the longitude I consider what meridian passeth through it, which is the meridian (_NDS_) which crosseth the AEquinoctiall in (_I_) at 15 degrees, wherefore I say that (_D_) stands Eastward from the first Meridian 15 degrees. So I finde that the Citty (_E_) is 150 degrees Eastward, (_G_) 195, and (_F_) 345. For the Latitude I consider what paralell runnes through (_DEG_) or (_F_) and I finde the 30 to passe by (_D_) 45 by (_E_) the 15 by (_F_) the 45 Southward by (_G_) and those numbers are the latitude of the place that are distant from the AEquator, (_CAB_). [Illustration] Concerning the means whereby the longitude of places is found out, there is scarce any thing that hath troubled Mathematicians so much as the observation of it. For because no standing marke can be taken (the Heavens alwaies running about) it must needs bee difficult. To measure vpon the earth, going alwaies vnder the same paralell, is a way certain in regard of some few places, but so troublesome in it selfe, and vnprofitable in regard of other places that ly out of that paralell, that it may be accounted a fruitlesse labour. The voyages & accounts of Marriners at Sea, are so full of casualty & vncertainty by reason of the doubtfull variation of the compasse, the vnequall violence of windes and tides, the false making of their sea cards, by which they saile, and the ignorance of the Masters for the greatest part, as there can hardly be any assured reckoning made by them. The best means of observation is by Eclipses of the Sunne & Moone, which in severall Countries are sooner or later seene, according as one place lies farther East or farther West from another. But this also falls out so seldome, and when it happens, is so seldome obserued, and when it is observed, hath so many difficulties in the precise and exact observation of it; that wee may Well account this inquiry after the longitude of places, to be one of those things whereof wee must be content to be ignorant, & rather to gesse at it in Grosse, then in vaine to striue for exactnesse, which is the cause why the tables of the longitude and latitude of Citties, though they many times agree in the latitude, doe yet for the most part very much differ in the Longitude.