240 



THE POPULAR EDUCATOR. 



covered a very small one with a tenth magnitude star near to it. 

 This was afterwards observed and its position noted by other 

 astronomers, but in 1861 it had entirely disappeared. Another 

 nebula, which had frequently been observed as a well-defined, 

 compact cluster, was found, in May, 

 1860, to be replaced by a star of the 

 seventh magnitude. After a few weeks 

 the stellar appearance had ceased, and 

 the cluster seemed to be resuming its 

 nsual form. 



The question as to tha real constitu- 

 tion of the nebulas r'.s one that has 

 given rise to much inquiry and contro- 

 versy. There seems now to be little 

 or no doubt that many of them are 

 universes somewhat resembling our 

 own, immensely removed from us. 

 This theory rapidly gained ground 

 as one after another of the nebulae 

 was resolved, by the construction 

 of more powerful telescope?, and it 

 was very generally believed that all 



the nebulae would ultimately be thus resolved. The hypo- 

 thesis previously received was that they consist merely of 

 masses of cloud-like matter, and modern researches seem now 

 to indicate that in some few eases this may be correct. When 

 the spectroscope was 

 first directed to one 

 of these objects, nc 

 spectrum could be ob- 

 tained, but merely a 

 short luminous band. 

 A second and third 

 much fainter bands 

 were afterwards made 

 out, and these lines 

 were found to corre- 

 spond with those in- 

 dicative of nitrogen, 

 hydrogen,and barium. 

 These facts seem to 

 point strongly to the 

 conclusion that the 

 nebulas did not con- 

 sist of solid matter, 

 but merely of an in- 

 candescent gas. 



The Nebular Hypo- 

 thesis, as it is termed, 

 not only accounts for 

 the nebulae, but also 

 for the formation of 

 entire 



our entire system. 

 According to it, the sun and all the planets originally existed in 

 the form of a globular mass of nebulous matter, filling a space 

 greatly exceeding the orbit of Neptune. This mass was set in 

 rotation, and, as it gradually cooled, became more and more 

 condensed, until at length some part 

 assumed the liquid form, and would 

 then form a ring surrounding the cen- 

 tral mass. This ring was, of course, in 

 rotation, and as it could scarcely be of 

 uniform thickness throughout, would 

 soon break up ; the matter composing 

 it was then collected into a ball still 

 rotating around the centre, and at the 

 same time turning on its own axis. 



In this way all the planets were in 

 turn formed, and they, by centrifugal 

 force, threw off their satellites and 

 rings, till at length the system was 

 complete, and the planets cooled down 

 into solid masses. The comets and 

 nebulas, then, consist of uncondensed portions of this matter 

 etill existing in space. 



The theory is a most plausible and ingenious one, and ac- 

 counts fully for the most remarkable features in the planetary 

 motions, namely, the motion of the planets in the same direc- 



tion, and nearly the same plane ; the motion of the secondaries 

 in the same direction as their primaries ; and the coincidence 

 in direction of the motion of the planets on their own axes with 

 their motion round the sun. The flattening of the planets at 

 the poles further tends to uphold this 

 theory, \7hich thus seems to have the 

 balance of probabilities greatly in its 

 favour. 



We have now completed our hasty 

 survey of this, the most wondrous and 

 sublime of all the sciences. Passing 

 from the early and rude observations 

 of shepherd astronomers, down to the 

 grand discoveries of modern times, wtf 

 have seen how step after step has been 

 taken in solving the mysteries of the 

 heavens ; and how, by the united and 

 persevering eiforts of a long series of 

 astronomers, our knowledge of the 

 heavenly bodies has steadily increased. 

 Instead of the apparent disorder and 

 confusion which the earliest astronomers 



imagined to exist, we find the most perfect order and harmony, 

 and behold all those stupendous orbs rolling on in their courses 

 and sustained by the action of a few grand yet simple laws. 

 We have, as it were, just opened the door to the student of 



Nature, and having 

 pointed outthe bound- 

 less fields of investi- 

 gation which stretch 

 before him, we leave 

 him at the threshold 

 to pursue his onward 

 course. A series of 

 papers like the pre- 

 sent cannot intro- 

 duce him to all the 

 depths of the science. 

 If, however, he has 

 followed us, he will 

 have acquired such 

 an acquaintance with 

 its first principles as 

 will enable him to pro- 

 coed further and fur- 

 ther in his inquiries, 

 and though he will 

 often meet with diffi- 

 culties, patient obser- 

 vation and thought 

 will enable him to 

 overcome most, if not 

 all of them. 



Let us, however, remember that, as has been said, 

 "The undevout astronomer is mad." 



As we gaze on the endless range of suns and systems which 

 crowd the sky, and by the aid of our 

 powerful instruments discover nume- 

 rous other systems infinitely more 

 distant from us, let us learn some- 

 thing of His Glory who made them all. 

 As we form some faint idea of the 

 immensity of these systems, and be- 

 hold in them all constant motion, and 

 yet the utmost stability, let us learn 

 His Power, and remember that " His 

 single arm guides the millions of 

 sweeping suns, and around His throne 

 circles the great constellation of un- 

 numbered universes ; " and, as we 

 behold the wondrous adjustments by 

 which each globe is poised in the 

 system, and made to move on in its own appointed path, let us 

 admire His matchless Wisdom, and learn His Omniscience. 

 Truly all these things should make us exclaim with the inspired 

 writer, " The heavens declare ^ the glory of God ; and the firma- 

 ment sheweth His handiwork." 



