SECTION XIX. Q$g earth, created it not in vain, because heformed it to be inhabited; Isa. xlv. 18. He thereby insinuates, that had such a globe as the earth never been inhabited, it had been in vain. Now the same way of reasoning may be applied to the other planetary worlds, some of which are so much bigger than the earth is, and their situations or motions seem to render them as con- venient dwellings for creatures of some animal and intellec- tual kind. Many of these things have been performed by ingenious men with great exactness, for the use of persons learned in the mathematics; but I know not any short, plain and intelligible account of them fitted for the use of the unlearned world, except among Dr. Wells' volumes, entitled Mathematics for a Young Gentleman : Yet I persuade myself, that some parts of it might be performed with greater ease and clearness, in a more natural method, and to much greater perfection, if some person of pecu- liar skill in these sciences and of equal condescension would un- dertake the work. SECT. XIX.Probleme relating to Geography and flstronomy to be performed by the Globe. AS theorems in mathematic science are certain propositions declaring some mathematical truth : So a problem is a mathe- matical question proposed to be resolved, or some practice to be performed. Because this problematic part will require the recol- lection of a great many things in the former sections, I think it may not be improper to give a short summary of definitions of the chief subjects of discourse in the doctrine of the sphere, and set them in one view. DEFINITION S.The latitude of a place on the earthly globe, is the distance of the zenith of that place from the equator to- ward the north or south pole measured by the degrees of the meridian. The elevation of the pole is the height of the pole above the horizon of that place measured on the meridian : And it is al- ways the same number of degrees as the latitude. The longitude of a place is the distance of-it toward the east or west from some first meridian, and it is measured on the equator. Thedeclination of the sun or any star or planet is its dis- tance- northward or southward from the equator measured on the meridian. It is the same thing as latitude on the earthly globe. The right ascension of the sun is its distance from that meridian that cuts the point aries measured eastward on the equator ; it is much the same with longitude on the earthly globe.
RkJQdWJsaXNoZXIy OTcyMjk=