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'axis, and observe the two points of tKe ecliptic which pass exactly under that degree of latitude, and look on the horizon for the two days of the year in which the sun is in those points or degrees of the ecliptic, and they are the days required; for oh them, and none else, the sun's declination is equal to the latitude of the given place.
Problem vm. Tojind the anfcect, ptricect, and antipodes of any given place.
Bring the given place to the brazen meridian, and having found its latitude, keep the globe in that position, and count the same number of degrees of latitude on the meridian, from the equator towards the contrary pole, and where the reckoning ends, that will give the place of the antceci upon the globe. Those who live at the equator have no antceci.
The globe remaining in the same position, bring the upper XII, on the horary circle, to the meridian, then turn the globe about till the meridian points to the lower XII; the place which then lies under the meridian, having the same latitude with the given place, is the perkeci required. Those who live at the poles, if any, have no pe~ rioeci. .' „.
'As the globe now stands (with the index at the lower XII), the antipodes of the given place are under the same point of the brazen meridian where, its antceci stood before.
Problem ix. Tojind at iqhat hour the sun rises and sets any day in the year, at any place, and also upon what point of the -conipass.
Rectify the globe for the latitude of the given place; bring the sun's place to the meridian, and bring the XII to the meridian; then turn the sun's place to the eastern edge of the horizon, and the meridian will point out the hour of rising; if you bring it to the western edge of the horizon, it will shew the setting.
Thus, on the 26th day of March, the sun rose a little past six, and set a little before six. .
Note. In the summer the sun rises and sets a little to the northward of the east and west points, but in winter a little to the southward of them. If, therefore, when the sun's place is brought to the eastern and western edges of the horizon, you look on the inner circle, right against the sun's place, you will see the point of the compass upon which the sun rises and sets that day.
Problem x. To find the length of the day and night at any time of the year.
Only double the time of the sun's rising that day, and it gives the length of the night; double the time of his setting and it gives the length of the
This problem shews how long the sun is with us on any day, and how long he is absent from us on any night.
Thus on the 26th of May, the sun rises about four, and sets about eight; therefore the day is sixteen hours long, and the night eight.
Problem xi. Tojind the length of the longest or shortest day, at any place upon the eartfu
Rectify the globe for that place, bring the beginning of Cancer to the meridian, bring XII to the meridian, then bring the same degree of Cancer to the east part of the horizon, and the meridian will shew the time of the sun's rising.
If the same degree be brought to the western side, the meridian will shew the setting, which, doubled, (as in the last problem) will give the length of the longest day and shortest night.
If we bring the beginning of Capricorn to the meridian, and proceed in all respects as before, we shall have the length of the longest night and shortest day.
Thus, in the Great Mogul's dominions, the longest day is fourteen hours, and the shortest night ten hours. The shortest day is ten hours, and the longest night fourteen hours.
At Petersburg!! the longest day is about 19! hours, and the shortest night 4i hours; the shortest day 4f hours, and longest nigh$ 19! hours,
Note. In all places near the equator, the sun rises and sets at six the year round. From thence to the polar circles, the days increase as the latitude increases; so that at those circles themselves, the longest day is twenty-four hours, and the longest night just the same. From the polar circles to the poles, the days continue to lengthen into weeks and months; so that at the very pole, the sun shines for six months together in summer, and is absent from it six months in winter.
Note. That when it is summer with the northern inhabitants, it is winter with the southern, and the contrary; and every part of the world partakes of an equal share of light and darkness.
Problem xii. To Jind all those inhabitants to horn the sun is this mome their meridian or midnight.
whom the sun is this moment rising or setting, in
Find the sun's place in the ecliptic, and raise the pole as much above the horizon as the sun (that day) declines from the equator; then bring the place where the sun is vertical at that hour, to the brass meridian; so will it then be in the zenith or centre of the horizon. Now see what countries lie on the western edge of the horizon, for in them the sun is rising; to those on the eastern side he is setting; to those under the upper part of the meridian it is noon day; and to those under the lower part of it, it is midnight.
Thus, on the 25th of April, at six o'clock in the evening, at Worcester,
The sun is rising at New Zealand: and to those who are sailing in the middle of the Great South Sea,
The Sun is setting at Sweden, Hungary, Italy, Tunis, in the middle of Negroland and Guinea.
In the meridian (or noon) at the middle of Mexico, Bay of Honduras, middle of Florida, Canada, &c.
Midnight at the middle of Tartary, Bengal, India, and the seas near the Sunda isles.
Problem xin. Tojind the beginning and end of twilight.
The twilight is that faint light which opens the morning by little and little, in the east, before the sun rises; and gradually shuts in the evening in the west, after the sun is set. It arises from the sun's illuminating the upper part of the atm«sphere, and begins always when he approaches within eighteen degrees of the eastern part of the horizon, and ends, when he descends eighteen degrees below the western; when dark night commences, and continues till day breaks again.
To find the beginning of twilight, rectify the globe; turn the degree of the ecliptic, which is opposite to the sun's place, till it is elevated eighteen