SYZYGY, in astronomy, a term equally used for the conjunction and opposition of a planet with the sun. On the pheno mena and circumstances of the syzygies, a great part of the lunar theory depends. For, 1. It is shown in the physical astro nomy, that the fbrce which diminishes the gravity of the moon in the syzygies, is double that which increases it in the quadratures: so that in the syzygies, the gravity of the moon, from the action of the sun, is diminished by a part which is to the whole gravity as 1 to 89,36 : for in the quadratures, the addition of gravity is to the whole gravity as 1 to 17b,73. 2. In the syzygies, the disturbing force is di rectly the distance of the moon from the earth, and inversely as the cube of the distance of the earth from the sun. And at the syzygies, the gravity of the moon to wards the earth, receding from its centre, is more diminished than according to the inverse ratio of the square of the distance from that centre. Hence, in the motion of the moon from the syzygies to the quadraturea, the gravity of the moon to wards the earth is continually increased, and the moon is continually retarded in its motion ; and in the motion from the quadratures to the syzygies, the moon's gravity is continually diminished, and its motion in its orbit accelerated. 3. Fur ther, in the syzygies, the moon's orbit, or circle, round the earth, is more convex than in the quadratures, for which reason the moon is less distant from the earth at the former than the latter. -When the
moon is in the syzygies, her absides go backwards, or are retrograde.
When the moon is in the syzygies, the nodes move in antecedentia fastest : then slower slower, till they become at rest, when the moon is in the quadra tures.
Lastly, When the nodes are come to the syzygies, the inclination of the plane of the orbit is least of all. Add that these several irregularities are not equal in each syzygy, bat all somewhat greater in the conjunction than in the opposition.
Nil Or t, the nineteenth letter, and fif teenth consonant, of our alphabet, the sound whereof is formed by a strong expulsion of the breath through the mouth, upon a sudden drawing back of the tongue from the fore part of the pa late, with the lips at the same time open. The proper sound of this that in tan, ten, tin, &c. When it comes before 1, followed by 'a vowel, it is sounded like s, as in nation, potion, &c. When h comes after it, it has a twofold sound ; one clear and acute, as in thin, thief, &c. the other more obtuse and obscure, as in then, there, &c.