1 50 Astronomical Society. 



the results for the planet's mean distance, which are as be- 

 low : viz. 



1. The external diameter of the external ring = 40"*215 



2. internal do. 35 -395 



3. external internal ring 34 '579 



4. internal do. 26 '748 



5. equatorial diameter of Saturn 18 '045 



6. breadth of the external ring 2 *410 



7. do. chasm between "I L, .,._ 



.i • > '408 



the rings J 



8. do. internal ring . 3 \915 



9. Distance of the ring from Saturn 4 *352 



10. The equatorial radius of Saturn 9 *022 



The mean value of the inclination of the ring to the ecliptic 

 is 28° 5'*9, with a probable error not exceeding 6 ,- 9. 



M. Struve has detected no trace of a division of the ring 

 into many parts; but he observes that the outer ring is much 

 less brilliant than the inner. The five longest-known satellites 

 are readily distinguished, through Fraunhofer's telescope, even 

 in the illuminated field. The 4th appears like a small disc, 

 diameter 0"*75. M. Struve saw the 6th several times; but 

 he has never seen the 7th ; of whose existence indeed Schroe- 

 ter entertains doubts. 



The same paper also details the results of micrometrical 

 measurements of Jupiter and its satellites, made with the same 

 instruments and with the same power 540, or from thence to 

 600. The mean results at the mean distance of the planet 

 from the earth, are, 



1. Jupiter's major axis .... 38"*442 



2. minor axis .... 35 '645 



3. compression 0"*0728 or T ^ TT 



4. Mean diam. l/'s 1st Sat. . l"-018 



5. 2d . -914 



6. 3d . 1 -492 



7. 4th . 1 -277 



Schrb'eter and Harding have often imagined that they have 

 detected a deviation of Jupiter from the elliptical form ; and 

 so thought Struve at first ; but a closer examination enables 

 him to explain the illusion. On March 7th this year, he 

 thought the diameter which extended from 61 0, 4 lat. preceding 

 S. to 61°*4 lat. following N., was obviously smaller than the 

 ellipsis would allow. But the micrometric measurement proved 

 that that was not the case. That evening the major axis, A, 

 was 44"*75; the minor axis, B, was 41"*72; and the diameter 



in 



