140 NINTH ANNUAL REPORT OF 



the limits of the charts, it was at once pounced upon as an unlicensed 

 wanderer. 



The discoveries ot" Gasparis were also made partly by comparing 

 the Berlin maps with the heavens, and partly by a series of observa- 

 tions in zones of declination, made for the express purpose of finding 

 new planets. Nearly all the asteroids have been discovered by a sys- 

 tematic comparison of the visible state of the heavens, with the state as 

 recorded in charts. 



The rapid discovery of twenty-nine new asteroids, after a barren 

 interval of almost forty 5^ears from the discovery of Vesta, is calculated 

 to excite surprise; but it is explained by the diminutive size of the new 

 planets, and the great increase in the number of observers, as well as • 

 the use of more powerful instruments. Vesta appears like a star of 

 the sixth magnitude, Pallas of the seventh, while Ceres and Juno are of 

 the eighth. Of the twenty-nine asteroids more recently discovered, 

 none of them, with perhaps two exceptions, are larger than the ninth 

 magnitude, while several are as small as the tenth, and one or two 

 scarcely, if ever, rise so high as the tenth magnitude. The reason that 

 Olbers was not more successful in his search was that he employed a 

 telescope of too feeble power, and did not extend his examination be- 

 yond stars of the eighth magnitude. 



Some may conclude that the number of asteroids already known is 

 so great that the discovery of additional ones is a matter of no interest, 

 and is unworthy the attention of astronomers. I regard the question in 

 a very different light. If only one planet had hitherto been discovered 

 between Mars and Jupiter, our idea of the simplicity and perfection of 

 the solar system would have been satisfied ; and there might have been 

 found ingenious minds attempting to prove by a priori reasoning, that 

 no other planets could possibly exist, unless beyond the limits of the 

 orbit of Neptune. But our theory of the solar s^^stem, altiiough appa- 

 rently simple, would not have been the true theory. Every new dis- 

 covery shows the solar system to be more complex than we had 

 supposed ; and unless we prefer error (provided it has a show of sim- 

 plicity) to truth, when it appears to our view complex, we shall value 

 every new discovery in the solar system, because it promises to conduct 

 us nearer to the true theory of the universe. Every new asteroid 

 which is discovered is a new fact to be explained. It presents a new 

 test by which every theory is to be tried. The true philosopher, 

 instead of regarding the rapidly increasing number of asteroids with 

 indifference, will watch each new discovery with growing interest, in 

 the hope that it may furnish the key to the true theory of the solar 

 system. 



The existence of thirty-three planets revolving round the sun, at dis- 

 tances closely allied to each other, and differing from all the other 

 planets in their diminutive size, is one of the most singular phenomena 

 in our solar system. This fact will appear the more striking if we 

 draw a diagram representing the orbits of all the known planets in their 

 proper proportions. We shall find that while the orbits of JMercury, 

 Venus, the earth, and Mars are quite detached from each other, and 

 the orbits of Jupiter, Saturn, Uranus, and Neptune are separated by 

 intervals which the imagination can scarcely grasp ; between Mars 



