8 HISTORY OF 



calculate the returning periods of many of them ; but experience 

 has not, as yet, confirmed the veracity of their investigations. 

 Indeed, vi^ho can tell, when those wanderers have made their 

 excursions into other M'orlds and distant systems, what obstacles 

 may be found to oppose their progress, to accelerate theil 

 motions, or retard their return ? 



towards the sun, its faint and nebulous light becomes more brilliant, and its 

 luminous train gradually increases in length. When it reaches its perihelion, 

 the intensity of its light, aud the length of its tail, reach their maximum, and 

 sometimes it shines with all the splendour of Venus. During its retreat 

 from the perihelion, it is shorn of its splendour, it gradually resumes its 

 nebulous appearance, and its tail decreases in magnitude till it reaches such 

 B distance from the earth, that the attenuated light of the sun, which it re. 

 fleets, ceases to make an impression on the organ of sight. Traversing un. 

 seen the ri^mote portion of its orbit, the comet wheels its ethereal course far 

 beyond tlio limits of our system. What region it there visits, or upon what 

 dHstiiiation it is sent, the limited powers of man are unable to discover. 

 After the lapse of years, we perceive it again returning to our system, and 

 tracing a portion of the same orbit round the sun, which it had formerly 

 described. It would be a waste of time to detail the various wild and extra. 

 vagant opinions which have been entertained respecting these interesting 

 stars. During the ages of barbarism and superstition, they were regarded 

 «s the harbingers of awful convulsions, both in the political and in the phy- 

 sical world. Wars, pestilence, and famine, the dethronement of kings, the 

 fall of nations, and the more alarming convulsions of the globe, were the 

 dreadful evils which they presented to the diseased and terrified imaginatioas 

 of men. As the light of knowledge dissipated these gloomy apprehensions, 

 the absurdities of licentious speculation supplied their place, and all the in- 

 genuity of conjecture was exhausted in assigning some rational office to 

 these wandering planets. Even at the beginning of the 18th century, the 

 friend and companion of Newton regarded them as the abode of the damned. 

 Anxious to know more tlian what is revealed, the fancy of speculative theo. 

 logians strove to discover the frightful regions in which vice was to sufftr 

 its merited punishment ; and the interior caverns of the earth had, in general, 

 been regarded as the awful prison-house in which the Almighty was to dis- 

 pense Uie severities of justice. Mr Whiston, however, outstripped all his 

 predecessors in fertility of invention. He pretended not only to fix the resi. 

 dence of the damned, but also the nature of their punishment. Wheeled 

 from the remotest limits of the system, the chilling regions of darkness and 

 cold, the comet wafted them into the very vicinity of the sun ; and thua 

 alternately hiuried its wretched tenants to the terrifying extremes of chil. 

 ling cold and devouring fire. By other astronomers, comets were destined 

 for more scientific purposes. They were supposed to convey back to the 

 planets the electric fluid which is constantly dissipating, or to supply the sun 

 with the fuel which it perpetually consumes. They have been regarded also 

 as the cause of the deluge ; and v/e must confess, that if a natural cause is to 

 be sought for that great event, we can explain it only by the shock of some 

 celestial body. The transient effect of a comet passing near the earth, coul.t 



