1.* INTRODUCTION. 



C0Lu9.Es... .If we imagine two great circles both passing through 

 the poies of the world, and one of them through the equinoctial 

 points Aries and Libra, and the other through the solstitial points- 

 Cancer and Capricorn, these are called the Colures ; the one the 

 Equinoctial, the other the Solstitial Colure. These are all the 

 great circles. 



Tropics. ...If we suppose two circles drawn parallel to the equi- 

 noctial, at twenty-three degrees thirty minutes distance from it, 

 measured on the brazen meridian, the one towards the north, the 

 .other towards the south, these are called Tropics, from the Greek 

 word rpoTrv, a turning, because the sun appears, when in them, to 

 turn backwards from his former course. The one is called the 

 Tropic of Cancer, the other of Capricorn, because they pass through 

 the first points of these signs. 



Polar circles. ...If two other circles are supposed to be drawn at 

 the like distance of twenty-three degrees thirty minutes, reckoned 

 on the meridian from the polar points, these are called the Polar 

 Circles. The northern is called the Arctic, because the north pole 

 is near the constellation of the Bear, in Greek upKTtn;; the southern, 

 the Antarctic, because opposite the former. And these are the/bur 

 less circles. 



Zones. ...After the four less circles we have mentioned were 

 known, it was observed that the earth, by means of them, might be 

 divided into five portions, and consequently that the places on its 

 surface might be distinguished according as they lay in one or 

 other of these portions, which are called Zones, from the Greek 

 word cf<yvjj, which signifies a girdle ; being broad spaces, like swathes, 

 girding the earth about. 



The torrid zone is that portion of the earth between the tropics, 

 and called by the ancients torrid, because they conceived, that being 

 continually exposed to the perpendicular or direct rays of the sun, 

 it was rendered uninhabitable, and contained nothing but parched 

 and sandy deserts. This notion, however, has long since been re- 

 futed. It is found that the long nights, great dews, regular rains 

 and breezes, which prevail almost throughout the torrid zone, ren- 

 der the earth not only habitable, but so fruitful, that in many pla- 

 ces they have two harvests in a year ; all sorts of spices and drugs 

 are almost solely produced there ; and it furnishes the most perfect 

 metals, precious stones, and pearls. In short, the countries of Afri- 

 ca, Asia, and America, which lie under this zone, are in all respects 

 the most fertile and luxuriant upon earth. 



The two temperate zones are comprised between the tropics and 

 polar circles. They are called temperate, because, meeting the 

 rays of the sun obliquely, they enjoy a moderate degree of heat. 



The two frigid zones lie between the polar circles and the poles, 

 or rather are enclosed within the polar circles. They are called the 

 frigid or frozen, because most part of the year it is extremely cold 

 there, and every thing is frozen so long as the sun is under the hori- 

 zon, or but a little above it. However, these zones are not quite 

 uninhabitable, though much less fit for living in than the torrid. 



None of all these zones have been fully explored by the Euro- 

 peans. Our knowledge of the southern temperate zone is very 

 imperfect; we know little of the northern frigid zone, and still less 

 of the southern frigid zone. The northern temperate and torrid 

 aones are those we are best acquainted with. 



