SÈC,T.ION XIX. 277 called culminating) also where it is day -light, twilight, or dark night. By the foregoing problem, find the place where the sun is vertical at the hour given ; rectify the globe for the latitude of that place; bring that place to the meridian. Then all those places that are in the west semi-circle'of the horizon have the sun rising, for it is 90 degrees from their zenith. Those in the east semi - circle of the horizon have it setting, for it is 90 degrees past their zenith. To those who live under the sane line of longitude or upper-meridian, it is noon, if they have any day at that time. To those who live under the opposite . line of longitude or lower meridian, it is midnight, if they have any night at that time. Thoseplaces that are above the horizon, have the sun above their horizon so many degrees, as the places themselves are. Thoseplaces that are under the horizon, but within 18 degrees, have twilight. And with those who are lower than 18 degrees, it is dark night. Problem XV. as A place being given in the' torrid zone, to find those two days in which the sun shall be vertical there." Bring the place to the meridian ; mark the degree over it, which is its latitude ; move the globe found, and observe these two opposite points of the ecliptic, that pass through the afore- said degree; search on the wooden horizon on what two days the sun passes through those two points of the ecliptic, for then the sun at noon will be in the zenith of the place given. ProblemXVI. " A place being given in'one of the frigid zones, (suppose the north) to find when the sun begins to'depart from, or to appear on that place, how longhe is absent, and how long he shines constantly upon it." Suppose the place givenbe the north Cape of Lapland 71 degrees of latitude. Rectify the globe for that place, or elevate the pole 71 degrees; then turn the globe till the descending part of the ecliptic, the meridian and south point of the horizon meet together.: Thus the ecliptic will shew, that the sun to- ward the end of Scorpio (that is; a little after the middleof November,) goes below the horizon entirely and leaves that part . of Lapland. Then turn the globe a little further, till the ascending part of the ecliptic meet the meridian in the same south point of the horizon, and it will shew that about the ninth or tenth degree of aquarius, that is, about the end of January, the sun begins to rise above their horizon. Thus they are at least twomonths with- out the sun in winter. In like manner bring the ascending part of the ecliptio to meet the meridian in the north point of the horizon, there you s3
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