[Sidenote:  Two causes of heat.] In the prouing of these colde regions habitable, I shalbe very short, because the same reasons serve for this purpose which were alleged before in the proouing the middle Zone to be temperate, especially seeing all heat and colde proceed from the Sunne, by the meanes either of the Angle which his beames do make with the Horizon, or els by the long or short continuance of the Suns presence aboue ground:  so that if the Sunnes beames do beat perpendicularly at right Angles, then there is one cause of heat, and if the Sunne do also long continue aboue the Horizon, then the heat thereby is much increased by accesse of this other cause, and so groweth to a kinde of extremitie.  And these two causes, as I sayd before, do most concurre vnder the two Tropicks, and therefore there is the greatest heat of the world.  And likewise, where both these causes are most absent, there is greatest want of heat, and increase of colde (seeing that colde is nothing but the priuation and absence of heate) and if one cause be wanting, and the other present the effect will grow indifferent.  Therefore this is to be vnderstood, that the neerer any region is to the Equinoctiall, the higher the Sunne doth rise ouer their heads at noone, and so maketh either right or neere right Angles, but the Sunne tarieth with them so much the shorter time, and causeth shorter dayes, with longer and colder nights, to restore the domage of the day past, by reason of the moisture consumed by vapour.  But in such regions, ouer the which the Sunne riseth lower (as in regions extended towards either pole) it maketh there vnequall Angles, but the Sunne continueth longer, and maketh longer dayes, and causeth so much shorter and warmer nights, as retaining warme vapours of the day past.  For there are found by experience Summer nights in Scotland and Gothland very hot, when vnder the Equinoctiall they are found very cold. [Sidenote:  Hote nights nere the pole.  Colde nights vnder the Equinoctiall.] This benefit of the Sunnes long continuance and increase of the day, doth argument so much the more in colde regions as they are nerer the poles, and ceaseth not increasing vntill it come directly vnder the point of the pole Arcticke, where the Sunne continueth aboue ground the space of sixe moneths or halfe a yere together, and so the day is halfe a yere long, that is the time of the Sunnes being in the North signes, from the first degree of Aries vntill the last of Virgo, that is all the time from our 10 day of March vntill the 14 of September. [Sidenote:  One day of sixe moneths.] The Sunne therefore during the time of these sixe moneth without any offence or hinderance of the night, giueth his influence vpon those lands with heat that neuer ceaseth during that time, which maketh to the great increase of Summer, by reason of the Sunnes continuance. [Sidenote:  Moderate heat vnder the poles.] Therefore it followeth, that though the Sunne be not there very high ouer