The Primary Planets. SOT 



small, the diameter of none of them probably 

 exceeding 100 miles, to admit of any accurate 

 observations by the best instruments now in use, 



JUPITEE is by far the largest planet in our 

 .svstem, and the brightest next to Venus in ap- 

 pearance. When viewed through a good tele- 

 scope, several belts, or bands, darker than the ge- 

 neral surface (see PL XXVII. figs. 115 and 116.) 

 are observed across his disc parallel to his equa- 

 tor, which, as they are constantly van-ing, are 

 supposed to be a series of clouds in his atmo- 

 sphere. Spots have also been seen on his disc 

 between the belts ; and from their disappearance 

 and reappearance, his diurnal rotation on his 

 axis has been computed at about 9 hours 55 mi- 

 nutes. His axis is nearly perpendicular to his 

 orbit ; his figure is an oblate spheroid, much flat- 

 tened at the poles. 



SATURN, when viewed through a good tele- 

 scope, is the most extraordinary and interesting 

 of all the planets. He is surrounded by a flat, 

 circular, broad, and luminous ring, (see fig, 114.) 

 which does not touch the planet, but casts a 

 shadow upon it, and is itself divided into two 

 parts. With respect to the nature of this extra- 

 ordinary phenomenon, no probable conjecture 

 has yet been formed. 



The GEORGIUM SIDUS, or URANUS, is too far 

 distant to admit of such accurate observation as 

 could be wished. It may sometimes be seen as a 



