FIGURE OF THE PLANET SATVRN. Q 



points of the greateft curvature not to be fo far north as 45 Obfervatlons on 



^ ° Saturn, by 



degrees. which its fingu- 



The evening being very calm and clear, I look a meafure br figure 13 af- 

 of their fKuation, which gives the latitude of the greatefl cur- "^'^'"'^'^' 

 vature 45® 21'. A fecond meafure gives 45'=' 41'' 



Jupiter being now at a confiderable altitude, I have viewed 

 it alternately with Saturn. The figure of the two planets is 

 decidedly different. The flattening at the poles and on the 

 equator of Saturn is much greater than it is on Jupiter, but the 

 curvature at the latitude of from 40 to 48^ on Jupiter is lefs 

 than on Saturn. ' 



I repeated thefe alternate obfervations many times, and the 

 oftener I compared the two planets together, liie more flriking 

 was their different firu(51ure. 



May 26. 10-leet refleclor. With a parallel thread micro- 

 meter and a magnifying power of 400, I took two meafures 

 of the diameter of the points of greatefl curvature, A mean 

 of them gave 6^4,3 divifions = 1 1'',98. After this, I took alfo 

 two meafures of the equatorial diameter, and a mean of them 

 gave 60,5 divifions = 11^',27; but the eciuatcuiai meafures 

 are probably too fmall. 



To judge by a view of the planet, I fliould fiippofe the 

 latitude of the greatefl curvature to be lefs than 45 degrees. 

 The eye will alfo diflinguifli the difference in the three dia- 

 meters of Saturn. That which paffes through the points of the 

 greatefl curvature is the largeft ; the equatorial the next, and 

 the polar diameter is the fmallefl. 



May 27. The evening being very favourable, I took again 

 kvo meafures of the diameter between the points of grealeft 

 curvature, a mean of which was 63,8 divifions = ll",88. 

 Two meafures of the equatorial diameter gave 61,3 divifions 

 = 11^44. 



June 1 . It occurred to me that a more accurate meafure 

 might be had of the latitude in which the greatefl curvature 

 takes place, by fetting the fixed thread of the micrometer to 

 the direction of the ring of Saturn, which may be done with 

 great accuracy. The two following meafures were taken in 

 this manner, and are more fatisfactory than I had taken before. 

 The firft gave the latitude of the fouth-precediug point of 

 greatefl curvature 43° 26'; and the fecond 43* 13'. A mean 

 of the two will be 43? 20'. 



June 



