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A is the position of the earth in its orbit at about September 21, or six months from its position at C. This is called the autumnal equinox. The same conditions prevail when the eafth occu- pies this position as when at C--equal day and night all over the world. The declination of the sun is nothing, but the sun is bound south instead of north as at C. For the position at A our fall and winter,is coming on. At C the -sun is bound north, and our spring and summer begins. At A we see the half of the earth the sun shines upon. At C we see the half in darkness. Remember, that the earth in these two positions ex- periences the same phenomena relative to the sun, the orbit, the plane of the ecliptic, etc. B is the position of the earth in its erbit at about Dec. 21, or winter solstice. The sun reaches its greatest south decli- nation--2314°. The earth in its orbit at this season of the year describes a small- er arc of the ellipse in which it revolves, and as the earth's axis is inclined to the plane of the ecliptic always by the same angle, its full amount is here experi- enced, since the axis in retaining this same inclination must bring one of the earth's poles closer to the sun and the other farther away. This is easily seen for in drawing a line to meet a_ hori- zontal line at an angle of 66%4°, the line first drawn is considerably tilted. The tilted line represents the earth's axis, and as the sun can only shine upon one-half of the earth at a time, the tilted portion must be either in the light or the dark of the sun, depending upon the position of the earth in its orbit. zz is the plane of the ecliptic and shows where the per- pendicular ray of the sun strikes the earth. The dotted line y" represents the same thing. In the one case it coin- cides with the equator, and in the other case 2314° below the equator. D is the position of the earth at the summer solstice, about June 21, declina- tion 23%4° north. z to y' in D is the are of the angle of the sun's declination on or about June 21, being then in it$ ex- treme limits. The declination is north because the plane of the ecliptic is north of the earth's equator. In the winter . solstice, B, the conditions are actually reversed, though the angle of the declina- tion is of the same amount but opposite in name, being south, z to y. In the spring and autumnal equinoxes, A and C of diagram, the sun's declination is 0° because there is no angle between the plane of the ecliptic and the equator, that is, a line drawn directly from the sun's center, at these times of the year, will strike the earth's equator, and they will be as one; at all other times such a line would strike north or south of the equa- tor, hence the term declination. TAE MaARINE. REVIEW Remember that the sun illuminates just one-half of earth each day, but this half of the earth is not from pole to pole. Only twice in the year does this occur. Whatever number of degrees the sun's light falls short of one pole its lights show the same number of degrees be- yond the opposite pole. The dotted line in Fig. 1, marked or- bit, is an ellipse. The importance of the ellipse arises from the fact that all the planets move in elliptical orbits, the sun being in one of the foci. LENGTH OF DAYS AND NIGHTS. Owing to the inclination of the earth's axis, there are but two points in the orbit where the light of the sun reaches both poles of the earth at the same time. These two points, March and September, are called equinoxes (equal days), for when the earth occupies either of these positions in its orbit, the days and nights are everywhere of equal length. At all other points in the orbit, except March and September, the light of the sun ex- tends beyond one pole, but fails to reach the others. As a result, more than half of the one polar hemisphere is illumi- nated, and its days are longer than its nights, while less than half of the other hemisphere is illuminated, and con- sequently in that hemisphere the days are shorter than the nights. By referring to the last diagram, and remembering that the earth is constantly rotating upon its axis as well as moving around the stin in its orbit, it will be seen that the days and nights are al- ways of equal length (12 hours) at the equator, but at all other places they are of unequal length, excepting when the earth is at the equinoxes. The days are shortest in the northern hemisphere and longest in the southern when the earth is at December. The reverse is the case six months later when the earth is at June "At these positions, called solstices, it is continuously day at one polar circle, and continuous night at the other, during a complete rotation of the earth, or 24 hours, while at the poles it is either continuous day or continuous night while the earth is passing from March to September, or for six months. THEORY OF THE SEASONS. The succession of the seasons depends upon the revolution of the earth, together with the inclination of the axis. When the earth is in the position of March 21 in diagram, it is the spring or vernal equinox, and the days and nights are everywhere of equal length. As the earth moves forward in its orbit, the north pole begins to incline toward the sun, the days lengthen in the northern hemisphere and shorten in the southern; and, since the sun reaches the zenith 29 of points north of the equator, the heat increases in the northern hemisphere while the cold increases in the southern. After 9214 days, or about June 21, the sun reaches the zenith of the tropic of Cancer. This is the summer solstice in the northern hemisphere, which receives the sun's rays most perpendicularly, and the winter solstice in the southern hemi- sphere, upon which the sun's rays falt most obliquely. As the earth advances, the sun day by day reaches the autumnal equinox, about Sept. 22. This is the be- ginning of spring in the southern hemi- sphere. Moving onward, the earth grad- ually presents its southern pole to the sun, while the north pole enters its an- nual period of cold and darkness. For 90 days the days in the northern hemi- sphere grow shorter until the winter sol- stice is reached about Dec. 21: This is the summer solstice, however, in the southern hemisphere, the time of its long- est day and most direct exposure to the sun, which reaches the zenith of the tropic of Capricorn. Passing on from this point in its orbit, the earth gradu- ally withdraws its south pole from the sun until after 90 days, it reaches the position of the vernal equinox again. It may be interesting to know that in the northern and southern hemispheres the duration of summer is not the same. The northern is the longer of the two, since the sun is on our side of the equator for 186% days, and to the southward of it for the remaining 17834 days. This is due to the eccentricity of the earth's or- bit, and the fact that we move in it faster when near the sun (our winter) than we do when further away (our summer). SIGNS OF THE ZODIAC, The earth advances 30° every month of the signs of the Zodiac, which causes the sun apparently to do the same in the opposite sign. The Zodiac represents that path in the heavens which the sun seems to describe by the earth's revolu- tion around it. A sign is a portion of the ecliptic containing 30°, or the 12th part of a circle. The first of the 12 signs commences at that point of the ecliptic through which the sun passes at the pe- riod of the vernal or spring equinox-- the signs are counted from west to east. A belt in the heavens extending 8° on each side of the ecliptic is called the Zo- diac, hence the term, "Signs of the Zo- diac." Their names, and the order in which they follow each other, are as follows: NORTHERN SIGNS. Aries--the Ram. Taurus--the Bull. Gemini--the Twins. _Cancer--the Crab. Leo--the Lion. Virgo--the Virgin