56 THE WORM). 



when it is in the meridian, or mid-heaven, and the meridian of a 

 place, is a plane, or direction, which passes through the spectator, 

 and the north and south point. If we observe another star which 

 rises 10 south of east, we will find it arriving to the meridian 

 something more than 10 lower down than the other star, 

 according to our latitude. If we were at the equator, it would be 

 just 10. This star would set 10 south of west, and so of any 

 stars whatever, they would all apparently describe diurnal circles, 

 or parts of such circles, all having the pole of the heavens for 

 their grand centre. Now at the time of the summer solstice, or 

 mid-summer, 21st of June, the sun rises directly east, and sets 

 due west, describing apparently a diurnal circle in the heavens, 

 after a few days, however, he will rise a little south of east, and 

 set a little south of west, and in a few days more he will rise still 

 farther south of east, and set so much south of west, until at the 

 time of the winter solstice, or mid-winter, he will, in our northern 

 latitude, rise very far towards the south, and come to the meridian 

 very low down, and set at as great a distance south of the west 

 point, as he arose south of the east. Now, if the backward motion 

 of the sun in the heavens, had been performed in a diurnal circle, 

 he would rise later and later each day, but always just at the 

 same distance from the east. Hence we infer, that this 

 backward motion of the sun, is not in a diurnal circle but inclined 

 to it. This is the case, the ecliptic, or sun's apparent path, 

 instead of corresponding with the equator, or with any particular 

 diurnal circle parallel to the equator, cuts them all at a certain 

 angle, which angle is called the inclination of the ecliptic. In 

 order to make this part of our subject clear, we must have 

 reference to a diagram. 



Let P P', be the poles of the celestial vault or concave, having 

 the earth A, within it, its poles being in the line P P'. As the 

 earth turns around on its axis, Jet its equator reach the heavens, 

 marking E E' as the celestial equator. Through a point B, at the 

 distance of 33| from the equator, suppose a line B S, which 

 also passes through the centre of the earth, to reach the sky at 

 S. As the earth turns around, this line, B S, will mark out a circle 

 in the heavens, C S, called, for a reason which will soon be given, 



