planets ought to be seen ; and on the first day of the present century, PIAZZI, 

 an Italian astronomer, had his attention engaged by a small star of the fifth 

 magnitude, which he thought presented peculiar appearances. He observed 

 it accordingly from night to night, and soon found that it had a motion among 

 the fixed stars, which was incompatible with the supposition that it could be a 

 body of that class. In short, he soon discovered that this object was a true 

 planet, and afterward applying to the observations made upon it the usual 

 methods of calculation, he found that it moved in the solar system round the 

 sun in the space between Mars and Jupiter, in such a position that its distance 

 from the latter was double its distance from the former. In short, it appeared 

 that this planet filled the vacant place. 



On the 28th of March, in the following year, Dr. OLBERS, of Bremen, dis- 

 covered the planet PALLAS, moving nearly at the same distance. In Septem- 

 ber, 1803, HARDING, also at BREMEN, discovered JUNO ; and finally, on the 

 29th of March, 1807, Dr. OLBERS discovered the fourth new planet, VESTA. 

 Thus within the first five years of the present century, four new members of 

 the solar system were discovered, presenting, among other anomalous circum- 

 stances, the spectacle of four planets equidistant from the sun, and therefore 

 all equally filling the vacant place declared to exist in the system by Kepler 

 and Bode. As these four planets move nearly at the same distance from the 

 sun, they also have nearly equal periods. 



The analogy prevailing between the distances of the planets, indicated by 

 Bode and Kepler, justified the expectation of the discovery of a single planet : 

 how, then, are we to reconcile the principle indicated by this analogy with the 

 known existence of four such bodies 1 This difficulty has been attempted to 

 be removed by the hypothesis that the four new planets are, in fact, fragments 

 of a single planet which has been broken ! But how, it may be asked, could 

 such a catastrophe as the fracture of a planet be brought about ? To this it is 

 answered that there are two causes the possibility and reality of which are 

 not disputed either of which might produce such an effect. The volcanic 

 phenomena developed on our own globe indicate to us the existence of internal 

 causes which may easily be supposed to acquire sulficient energy to cause the 

 explosion of the planet. The intersection, on the other hand, of the solar sys- 

 tem, by innumerable comets rushing among the planets constantly and in every 

 direction, renders the collision of such a body with a planet a possible occur- 

 rence. Either of these causes, then, being sufficient to produce the supposed 

 catastrophe, and both being possible, the next question to be settled is, whether 

 the circumstances attending the appearance, condition, and motion, of the new 

 planets, are such as would attend the fragments of a single planet exploded or 

 broken by either of these causes. 



In 't'e first place, then, it is evident that the magnitude of these four bodies 

 recently discovered afford a strong presumption in favor of such a supposition. 

 Their magnitudes are so minute, that astronomical observers as yet have been 

 unable to agree as to their dimensions ; but it seems certain that their diameters 

 do not amount to more than a few hundred miles. They are therefore not only 

 incomparably smaller than any of the other planets, but even smaller than the 

 satellites. It is estimated that the bulk of VESTA does not exceed the twenty- 

 five thousandth part of the earth. HERSCHEL states that the diameter of CERES 

 ) cannot much exceed a hundred and fifty miles, and that that of JUNO is under 

 ( one hundred miles. It is calculated that the aggregate of the volumes of all 

 ) these four planets united would not exceed the twenty-fifth pnrt of the bulk of 

 \ our globe. 



This minuteness of size is evidently a circumstance that might naturally be 

 \ expected in the fragments of a single planet ; and as from their smallness it is 



