GRAMMAR OF GEOGRAPHY. THE present volume, which is chiefly designed as an introduction to Geography, or a description of the earth and its inhabitants, cannot be fully comprehended without occasionally contemplating our globe in its relation to the other parts of the Solar System, and even in connection with the more remote celestial bodies: it therefore becomes necessary to preface the work with a brief outline of the principles of Astronomy. ASTRONOMY Is that sublime science which treats of the classification, arrangement, magnitudes, distances, and motions of the heavenly bodies; explains their mutual influences and actions upon each other, and demonstrates the laws by which their motions are regulated and sustained. 1. The term Astronomy is composed of two Greek words, signifying the law of the Stars, under which name the ancients comprehended not only the Stars properly so called, but the Sun, the Moon, and all the other celestial bodies. 2. These bodies are divisible into two great classes: the one erratic or wandering (implied in the word Planet), including the Planets and the Comets; the other fixed or stationary, comprising those bodies which preserve among themselves so much permanence, as to apparent relative situation, that no positive motion can be detected in them, unless by B the most delicate observations, made with the most accurate instruments, and continued through a long series of years. These are the Sun and those still retaining the name of Fixed Stars, which was applied to them long before a positive motion had been observed in any one individual of this class, and ought, therefore, now to be understood in a comparative, and not in an absolute sense, since many of them are at this time known, and all of them supposed, to be in a state of constant motion. THE SOLAR SYSTEM consists of the Sun, from which it takes its name; seven Primary Planets; four minor Primary Planets; eighteen Secondary Planets, also denominated Satellites or Moons; and an indefinite number of other very curious erratic bodies, called Comets. 3. THE SUN, the great source of light, heat, and vegetation to the planetary bodies which circulate about him, is 883,246 English miles in diameter. The surface of this great luminary is frequently found to be diversified by a number of perfectly black spots, surrounded by a fainter shade, called a penumbra These spots, which differ from one another in form, magnitude, and duration, move from east to west across the disc of the Sun, and seem to be confined to a region not extending more than about 30° from his equator. The period of their apparent revolution is 27 days, 7 hours, 37 minutes; which, due allowance being made for the progressive motion of the Earth in its orbit during that period, determines the true time of the Sun's rotation on his axis to be about 25 days, 9 hours, 56 minutes. 4. THE PRIMARY PLANETS are those which revolve round the Sun as a centre. They are seven in number; their order in the system, their names, and |