376 ANNUAL OF SCIENTIFIC DISCOVERY. 



things these eccentricities and these inclinations are totally incompatible 

 with Gibers' s hypothesis, which supposed that the small planets (some of 

 which were discovered even in his day) were produced from the wreck of 

 a larger star which had exploded. The forces necessary to launch the 

 fragments of a given body in such different routes, whose existence we 

 should be oblige to suppose, would be of such an improbable intensity 

 that the most limited mathematical knowledge could not but see its absurd- 

 ity. However, as the mutual actions of the celestial bodies belonging to 

 the same system give rise to perturbations which gradually deform their 

 primitive orbits, M. Leverrier resolved to examine whether the present 

 eccentricities and inclinations of the smaller planets might not owe their 

 origin to perturbing actions, whose effects have been accumulated with 

 time. He soon ascertained that in the annular zone between the orbits 

 of Mars and of Jupiter there are two very distinct regions, so far as re- 

 spects the bodies placed within them. The line of demarcation between 

 these two regions is distant from the sun the double of that commonly 

 kept by the earth. Beyond this distance the perturbations can permanent- 

 ly increase neither the eccentricity nor the inclination of the stars there- 

 in primitively established ; within this distance the conditions are changed ; 

 there is neither "stability" in the form nor m the inclinations of orbits. 

 Out of the twenty-seven small planets known to us, there is not one of 

 them which invades this dangerous field ; the nearest of them all still 

 keeps so respectful a distance as to assure itself an orbit analogous to that 

 it now describes. M. Leverrier concludes his memoir by advancing these 

 propositions, which forever annihilate Olbers's hypothesis. 1st. The 

 eccentricities of the orbits of the known small planets cannot receive from 

 perturbations but very slight changes ; these eccentricities (great as they 

 now are) have been, and always will be, great. 2d. The same truth ap- 

 plied to the inclination of the orbits ; so that the degree of the inclinations 

 and of the eccentricities is plainly deducible from the primitive conditions 

 of the formation of the group of these smaller planets. 3d. These prop- 

 ositions are true only for distances from the sun superior to 2.00, the dis- 

 tance of the earth being taken as the unity ; there would be no " stability " 

 for a small planet situated between Mars and a distance of 2.00. Plora 

 is found at a distance of only 2.20 from the sun, and is the nearest of the 

 smaller planets ; are there any within this zone ? We cannot tell, because 

 they are never at the same time sufficiently near us and sufficiently dis- 

 engaged from the solar light. 



ON THE RINGS OF SATURN. 



Sir David Brewster in a recent publication presents the following curious 

 and startling speculation respecting the rings of Saturn. He says, " Ac- 

 cording to very recent observations, the ring is divided into three separate 

 rings, which, according to the calculations of Mr. Bond, an American 

 astronomer, must be fluid. He is of opinion that the number of rings is 



