L. Trouveht— Physical Observations of iSalurn. 449 



r. fig. 1, were seen near the summit of the principal division of 

 the rings on the following side, and apparently projected upon 

 the ring B. After an interval of three hours, no sensible change 

 could be detected in the position of these forms ; and on the 

 following day they were seen occupying about the same position. 

 This phenomenon could easily be explained by supposing there 

 were some sort of protuberances on the external edge of the ring 

 0, casting their shadow under the oblique rays of the sun, which 

 occupied then a proper position to answer to this hypothesis. 

 But some days later, another of these singular forms was ob- 

 served 180° from the first, on the preceding side, at s. This at 

 once overthrew the supposition that they were shadows cast by 

 protuberances existing on the ring G; since in this case the 

 shadows would have been projected opposite the sun on the ring 

 C, and not on the ring B. Since that time, I have rarely ob- 

 served the planet without seeing some of these singular appear- 



ances, either on one side or the other, but generally on both 

 sides. The number of these dark forms is variable. One, two, 

 three, four, and even five, have been seen at the same moment, 

 and on the same side. Though these forms are variable, and 

 appear and disappear, I have never been able to detect in one 

 night any change of position which could be ascribed to the ro- 

 tation of the rings. i • i t 

 The most plausible explanation of the phenomenon which I 

 can conceive is, that the inner margin of the ring B, which forms 

 the outer limit of the principal division, is irregular, jagged, and 

 deeply indented, as shown at a, fig. 2, which represents Saturn 

 as it would appear to an observer placed above one of its poles. 



