CONVERSATION IV. Of the Ephemeris. CHARLES. Your second method of tracing the ecliptic was by means of the position of the planets: will you explain that now? Tutor. I will; and, to render you perfectly qualified for observing the stars, I will devote the present Conversation to the purpose of explaining the use of White's Ephemeris, a little book which is published annually, and which is a necessary companion to every young astronomer. James. Must we understand all this to study the stars? Tutor. You must; or some other book of the same kind, if you would proceed on the best and most rational plan. Besides, when you know the use of this book, which you will completely with half an hour's attention, you have nothing more to do in order to find the position of the planets at any day of the year, than to turn to that day in the Ephemeris, and you will instantly be directed to those parts of the heavens in which the different planets are situated. Turn to the second page. Charles. Here the astronomical characters are explained. Tutor. The first twelve are the representatives of the signs into which the circle of the ecliptic is divided, called also the twelve signs of the Zodiac. In astronomical inquiries every circle is supposed to be divided into 360 parts, called degrees, and since that of the ecliptic is also divided into 12 signs, each sign must contain 30 degrees. Astronomers subdivide each degree into 60 parts, called minutes, and each minute into 60 seconds; thus, if I would express an angle of 25 degrees, 11 minutes, and 45 seconds, I should write 25°.. 11'..45". Or, if I would express the situation of the sun for the first of January, 1822, I look into the Ephemeris and find it in Capricorn, or V 10°.. 35′.. 48". James. What do you mean by the Zodiac ? Tutor. It is an imaginary broad circle or belt surrounding the heavens, about sixteen degrees wide; along the middle of which runs the ecliptic. The term Zodiac is derived from a Greek word signifying an ani mal, because each of the twelve signs formerly represented some animal; that which we now call Libra being by the ancients reckoned a part of Scorpio. James. Why are the signs of the Zodiac called by the several names of Aries, Taurus, Leo, &c. I see no likeness in the heavens to Rams, or Bulls, or Lions, which are the English words for those Latin ones? Tutor. Nor do I; nevertheless, the ancients saw, by the help of a strong imagination, a similarity between those animals and the places which certain systems of stars took up in the heavens, and gave them the names which have continued to this day. Charles. Perhaps these were originally invented in the same way as we sometimes figure to our imagination the appearances of men, beasts, ships, trees, &c. in the flying clouds or in the fire. Tutor. They might possibly have no better authority for their origin. At any rate, it will be useful for you to have the names of the twelve signs in your memory, as well as the order in which they stand: I will therefore repeat some lines written by Dr. Watts, in which they are expressed in English, and will be easily remembered: The Ram, the Bull, the heavenly Twins, The Virgin and the Scales: |