meridian is (_ANBS_) which goes by the Canary Ilands, the
Æquinoctiall 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 Æquinoctiall 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 Æquator, (_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