3. The Horizon is two fold: { Sensible or appearing.
{ Intelligible or true.

_The Sensible or appearing Horizon is the space of the earth so
farre as in an open plaine, or vpon some Hill a man may see round
about him._ The brim or edge of the earth further then which you
cannot see, that is the Horizon, or as some call it the
_Finitor_. Because _finet_ or terminat _visum_ it setts the
limits or bounds to your sight, beyond which nothing can bee
seene vpon the earth. This is greater or lesser, according as the
height of the eye aboue the plaine superficies of the earth, is
more or lesse. The most exact triall hereof is at Sea, where
there are no mountaines nor any vnequall risings of the water to
hinder the sight, as there are at land. For example let (_CBAF_)
be the superficies of the Sea and let a mans eye bee placed in
(_X_) aboue the Sea; as the eye stands higher or lower so will
the distance seene be more or lesse, as if the hight of (_XA_) be
6 foot which is ordinary the height of a man, the eye looking
from (_X_) to (_B_) shall see 2 miles and 3 quarters, if (_X_) be
20 foote high (_BA_) will bee fiue miles, if 40 foote 7 miles, if
50 foote 8 miles.[1] So that from the mast of a ship 50 foote
high, a man may see round about at sea 8 miles every way, toward
(_BG_) and (_F_). So farre may the water it selfe be seene, but
any high thing on the Water may be seene farther, 16, or 20 miles
according as the height is, as the ship at (_C_) may be seene
from (_X_) as far more as it is from (_A_) to (_B_). There can be
therefore no certaine quantity and space set downe for this
sensible Horizon, which continually varies according to the
height of the eye aboue the plaine ground or sea. This Horrizon