EECREATIVE SCIENCE. 



On the 1st of January, 1801, Piazzi dis- 

 covered the planet Ceres, and tlie gap was 

 filled up ; yet, strange to say, in 1802, Dr. 

 Olbers discovered another (Pallas) at the 

 same mean distance from the sun as Ceres ; 

 and in 1803 Harding detected Juno, and in 

 1807 Dr. Olbers found Vesta ; all of which 

 can be represented by the number 28. Astro- 

 nomers at length began to argue that, as 

 these planets were very small, probably 

 others would be discovered, which, collec- 

 tively, would be equal in a somewhat similar 

 bulk to the other planets. However, no fur- 

 ther discoveries resulted until the year 1845, 

 when Hencke, after many years' dUigent ob- 

 servation, detected Astraea ; since which date 

 planet after planet has been- added to this 

 list, until it has rapidly become swollen to 

 sixty- four, fifty-six of which constitute a ring 

 of planetsi whose mean distance from the 

 sun niay be represented by S8, and to this 

 number no doubt others will be added. 



The numerical law of which we have been 

 speaking, gave promise of other bodies being 

 found exterior to Saturn ; 196 would repre- 

 sent the distance from the sun of a planet 

 exterior to Saturn, and such a planet (Uranus) 

 was detected by Sir William Herschel ; and 

 again, 388 would represent another still fur- 

 ther removed from the sun. 



Owiag to the power of gravitation, plane- 

 tary bodies exert an influence over each other ; 

 thus, a body can be pxilled outtoards if under 

 the influence of a body exterior to it, or in- 

 wards if of one interior to it. !N"ow Uranus 

 was observed to receive this outward in- 

 fluence, and, consequently, a planet exterior 

 to it was conceived to exist. A dozen years 

 ago the independent abstruse calculations of 

 M. Le Verrier, a French, and Mr.- Adams, an 

 English mathematician, based on these per- 

 turbations, were confirmed by the discovery 

 of the planet Neptune. 



Should another planet exist, still more re- 

 mote, at a numerical distance represented by 

 772, calculation may again be the means of 



finding a body so far removed from the sun j 

 and thus the solar system may be again 

 expanded considerably beyond the bounds 

 which it is now shown to occupy. 



We are apt to conceive that planets move 

 around the sun in almost circular paths, and 

 indeed they would do so, were it not for the 

 influence exerted upon them by other bodies. 

 Supposing that no influence were exerted 

 upon a planet, its motion would be repre- 



Fig. 3. 



sented by Fig. 3. Yet, as this is not the 

 case, the annexed diagram, Fig, 4<, of 



Fio. 4. 



a planet's orbit, acted upon by an extc' 

 rior planet in the one portion, and by an in- 

 terior planet in another portion of the orbit, 

 will give some idea of the efiect produced. 

 It is necessary to understand this, in order 

 to be conversant with the effects produced 

 by one body upon another — effects which, 

 studied by our best astronomers, have been 



