THE MAJOR PLANETS. 



Except therefore for an interval of a few months every fifteen years, the 

 rings of Saturn are always in a position to be seen from the earth. Thr.se cir- 

 cumstances occur when the planet passes through the twentieth degrees of tin- 

 signs Virgo and Pisces. They took place in the year 1832-'33, and will recur 

 again in 1847-'48. 



The angle at which the plane of the rings is inclined to that of the ecliptic 

 being about 30, the rings must always be seen obliquely from the earth, more 

 or less so, as the earth is more or less distant from the plane of the rings, but 

 the obliquity of. the view can never be less than 30. Now, since a circle 

 seen obliquely is always foreshortened into an oval, the appearance of 

 the rings, even in the most favorable position must be elliptical. If a circle be 

 viewed at an angle of 30, it will be seen as an ellipse whose lesser axis is 

 half its greater. Such is the form of the ring as seen at intervals of seven 

 years and a half from Saturn's equinoxes, or when the planet is in the siuns 

 Scorpio and Gemini, which takes place at the middle of the intervals of the 

 disappearances of the rings. This occurred last in 1839-'40, and will occur 

 again in 1854-'55. Between the epochs at which the ring is in its most 

 open state, and the times of its disappearances it undergoes all the intermedi- 

 ate phases. 



In the annexed figures the appearances it presented between 1832 and 1840 

 are given from the observations of William Dick. 



In October, November, and December, 1832, the ring appeared as in fig. 1. 

 In the beginning of January, it appeared like a pure thread of light on each 

 side of the planet as in fig. 2. It began to appear a little larger during die 

 months of January, February, and March, 1833 ; but in April it again disap- 

 peared as the earth was then in the plane of the ring, and it continued invisible 

 till near the end of June ; after which it again appeared as represented in fig. 

 2. In about a year after its second disappearance, it appeared as in fig. 3, and 

 a year and a half afterward was seen as in fig. 4. In 1837 it appeared as 

 in fig. 5, and finally assumed its most open form, as represented in fig. 6. 



From 1838 to 1847, the ring gradually passes through similar phases in a 

 contrary order. 



SATELLITES OF SATURN 



On examining Saturn with powerful telescopes, it is found to be attended by 

 objects revolving round it similar in all respects to the satellites of Jupiter, but 

 amounting to seven in number. These revolve nearly in the plane of the ring 

 and beyond that body. The times of revolution are such as to present various 

 and interesting appearances to the inhabitants of the planet. The nearest 

 satellite, makes its complete revolution in 22^ hours, which is equivalent to 

 about two of Saturn's days. This moon, therefore, exhibits all its various 

 changes within that time. It passes from the crescent to the first quarter 

 in half of one of Saturn's days ; from the first quarter to the full moon in an- 

 other half day. and from the full to the new moon in another half day ; so rapid 

 is the succession of its phases. The next in the order of distance, makes its 

 revolutions in thirty-three hours, or in about three of Saturn's days, which 

 constitutes another sort of month ; within which it passes through all its vari- 

 ous phases. The third revolves in forty-five hours, or abouv four of Saturn's 

 days ; the fourth in seventy-five hours, or about seven and a half of Saturn's 

 days ; the fifth in one hundred and eight hours, or nearly eleven of Saturn's 

 days ; the sixth in about three hundred and eighty hours, or in about thirty- 

 eight of Saturn's days ; the seventh in about nineteen hundred hours, or one 



