The adjoining diagram, on Plate No. II, may serve for an illustration. You will see from it, that the Earth is the third Planet from the Sun. Mercury and Venus come before it; the most remote from the Sun is _Herschel_, so called from the astronomer’s name, who has but lately discovered it. § 9. The Earth is constantly attended by One Satellite (Lesson I, § 5); Jupiter by Four (see the diagram), Saturn by Six, and Herschel by Seven. Saturn is, besides, constantly surrounded by a broad luminous ring, which distinguishes it from all other Planets, and of which we shall speak hereafter. § 10. With regard to the magnitude of the different Planets it has been observed that although some of them are much larger than Our Earth; yet in Comparison to the Sun they are but small bodies, as you may see from the figures on plate No. III, in which the different Planets are drawn in proportion to the Sun: you will perceive from it; 1. That the Sun is a great many times[1] larger than either of the Planets. [Illustration: _N^o. II._ ] [Illustration: _N^o. III._. ] 2. That the Sun is much larger than all the Planets (our Earth included) taken together. 3. That Jupiter is the greatest Planet in our solar system. 4. That Saturn is the second Planet with regard to magnitude. 5. That Herschel ranks third. 6. That the Earth ranks fourth; but that 7. Each of the other Planets and the Moon are smaller than the Earth. 8. That either of the Planets Ceres, Vesta, Juno, Pallas is smaller than the Moon. § 11. If you cut a ball or a sphere in halves, and through the centre of one of the flat surfaces, draw a straight line across the whole surface, then this line is called the _Diameter_ of the ball or sphere.—Now as the Sun and the Planets are nothing else but large balls or spheres (Lesson I, § 4), we may also speak of their Diameters.—Thus we say, “the Diameter of the Sun is so many times larger than that of the Earth; the Diameter of Jupiter is so many times larger than that of Venus,” etc. You will now easily understand what the straight line means, which, in plate No. III is drawn through the centre of the circle, which represents the Sun; also the straight lines which are drawn through the circles which represent the Planets.—You will also perceive from the first figure on plate No. III, that the Sun’s Diameter is larger than the Diameters of all the Planets taken together. § 12. Plate No. IV represents the _surfaces_ of the Planets, compared to that of the Sun.—For you must know that it is possible to _measure_ the surface of a sphere; which is done by supposing it to be spread out, and then seeing how many square inches, feet or yards it contains. This we have supposed to be done with the surfaces of the Sun and Planets, and accordingly, have drawn their square measurements, in Plate No. IV. in proportion to each other. You will see from this Plate: