“The western Sun withdraws: meanwhile the Moon, Full orb’d, and breaking through the scatter’d clouds, Shows her broad visage in the crimson’d east.” Early in autumn, when the evenings are frequently clear, many persons are led with more force than usual to evince an interest in our satellite, and to desire information which may not be conveniently obtained at the time. The aspect of the Moon at her rising, near the time of the full, during the months of August, September, and October, is more conspicuously noticeable than at any other season of the year, on account of the position she then assumes on successive nights, enabling her to rise at closely identical times for several evenings together. The appearance of her large, ruddy globe at near the same hour, and her increasing brilliancy as her horizontal rays give way under a more vertical position, originated the title of “Harvest Moon,” to commemorate the facility afforded by her light for the ingathering of the corn preceding the time of the autumnal equinox. It will be universally admitted that the Moon possesses special attractions for us, as being situated nearer than any other celestial body, and forming the inseparable companion or tributary world to the Earth. The many important influences she exercises have led to her becoming the object of close investigation; so that her motions and physical appearances have been ascertained with a remarkable degree of exactness and amplitude. Her movements regulate the tides; her positions are of the utmost moment to the mariner; her light is the welcome beacon of the wayfarer, and its picturesque serenity has ever formed the theme of poets. To the practical astronomer she constitutes an orb perfectly unique as regards extent and variety of detail; and questions relating to the physical condition of her surface, now and in past ages, supply a fund of endless speculation to the theorist. The mean apparent diameter of the Moon is 31′ 5″, and it varies from 29′ 21″ at perigee to 33′ 31″ at apogee. Her real diameter is 2160 miles, and her mean distance slightly exceeds 237,000 miles. Her revolution round the Earth (= sidereal period) is performed in 27^d 7^h 43^m 11^s·46, but the time from one new moon to another (= synodical period) is 29^d 12^h 44^m 3^s. The Moon’s motion through the firmament is at the rate of 13° 10′ 35″ per day and 32′ 56″ per hour. Thus she travels over a space slightly exceeding her own diameter in one hour. The linear value of 1″ at the distance of our satellite is 1·16 mile, and of 1′ 69½ miles.