i 



PvECEEATIVE SCIENCE. 



line, and again in an hour's interval, after 

 moving the screw so as to again place them 

 in the same straight line, it follows, that the 

 redaings of the vernier will give the exact 

 movement which has taken place during 

 that hour. 



Sometimes the number of stars in a cer- 

 tain map wiU he found to have diminished, 

 and then it is evident that a planet had been 

 previously mapped down as a star, and if 

 this stranger cannot be detected in an adja- 

 cent map, it will be lost for a time at aU 

 events. In this manner, and also owing to 

 clouds obscuring the sky before the requisite 

 verification coidd be accomplished, and the 

 heavens remaining overcast for several 

 weeks afterwards, some planets have eluded 

 the vigilance of observers. 



To the equatorial telescope we are in- 

 debted for aU these discoveries, for it is ab- 

 solutely requisite that we should be able to 

 turn to any particular portion of the heavens 

 that we may desire, in order to enable us to 

 return to the required spot. This telescope 

 moving on circles of right ascension and de- 

 clination, accurately divided into degrees, 

 minutes, and seconds of space, and having 

 dials which will show these positions, it 

 becomes an easy matter to find any required 

 portion of the heavens. Such telescopes are 

 more numerous than they used to be, and in 

 the hands of a corps of observers, both public 

 and private, and all directing their energies in 

 the same direction, it is not to be wondered 

 at, that such labours should be rewarded by 

 the discovery of bodies hitherto unknown. 



Another circumstance remains to be men- 

 tioned, i. e., formerly, astronomers were sa- 

 tisfied if they constructed maps of the stars 

 down to the 6th magnitude, now, such maps 

 descend to the 10th, 11th, and 12th magni- 

 tudes ; and as it is in the 9th, 10th, and 11th 

 magnitudes that the bulk of these planets are 

 classed, we can see a sufficient reason why so 

 many planets have been previously over- 

 looked. 



There is a singular history with regard to 

 Goldschmidt's planet Daphne, resulting in 

 the discovery of another new planet. Unfa- 

 vourable weather setting in soon after its 

 discovery, prevented a sufficient number of 

 observations being made in order to ascertain 

 its proper orbit; therefore this planet was 

 lost, and its discoverer set about the task of 

 rediscovering it. On the 9th of September, 

 1857, Goldschmidt conceived that he had 

 found it, but Schubert has since proved that 

 the object seen on that date could not be 

 Daphne, but a netu planet. A delicacy seems 

 to exist between Schubert and Goldschmidt 

 as to whom the discovery should be ascribed, 

 the latter having discovered it, yet thought 

 it to be Daphne, whilst the former, from cal- 

 culation, showed that it could not be that 

 planet. Hitherto it has received no other 

 name than Pseudo-Daphne, to distinguish it 

 from the true Daphne. 



With the exception of Neptune, the whole 

 of the new planets are what astronomers have 

 termed Asteroids, or minor planets, and their 

 discovery was in the first instance to be 

 ascribed to Professor Bode, of Berlin, who, in 

 the year 1772, ventured to predict the dis- 

 covery of a new planet. 



That well-known astronomer became aware 

 of the fact that a numerical relation existed 

 between the distances of the planets from 

 each other and from the sun. If we take the 

 numbers 0, 3, 6, 12, 24, 48, 96, 192, and 384, 

 and add 4 to each of them, we shall have 4, 

 7, 10, 16, 28, 52, 100, 196, and 388 expressing 

 the order and proportion of the distances of 

 the planets from the sun. Thus Professor Bode 

 found that 4 represented Mercury, 7 Venus, 

 10 tho Earth, 16 Mars, 52 Jupiter, and 100 

 Saturn, and that this numerical law held 

 good with all the planets, with the solitary 

 exception of a break between 16 (Mars) and 

 52 (Jupiter) ; there wanted a planet which 

 should be expressed by 28, and so satisfied 

 was Professor Bode that one existed, that he 

 boldly came forward, and predicted it. 



