THE SIDEREAL UNIVERSE. 753 



ridiculous hypotheses. Descartes thought they were only 

 old stars which had become crusted over and sick, and 

 which being too feeble to maintain their places, were borne 

 away by the vortices of neighbouring stars. 



The regular movements of comets seem to have been 

 suspected by Seneca, but it was Newton who taught the 

 method of calculating them. These vagabond stars, how- 

 ever, frequently move in such a way as to deceive all the 

 sagacity of astronomers. The reader may recollect, in 

 reference to this point, that Jacopo Bernouilli had an- 

 nounced the return of the comet of 1G80 for the 17th of 

 May, 1719; it ought, at this time, to have made a ma- 

 jestic entry into the sign of the Balance. Voltaire says, 

 that in order to see this beautiful spectacle, not a single 

 astronomer went to bed that night ; but the comet did not 

 appear. These wandering meteors are sometimes guilty 

 now-a-days of the same want of politeness.^ 



The learned themselves have contributed largely to all 

 the errors circulated by the vulgar alDout these strange 

 stars, and even astronomers, though least of all, have sup- 

 plied their contingent. At one time the appearance of 

 comets inspired such dread that people shut themselves 

 up in their dwellings in order not to see their horrible 

 aspect; now-a-days, on the contrary, we rush out of doors 

 the better to gaze upon their luminous tresses. Naturally 

 enough ignorant crowds were alarmed when the most 

 enlightened men, such as J. Bernouilli, maintained that 



^ Seneca suspected not only the regular movements of comets, but even the 

 possibility of tracing their path by means of calculation. "I look ujion them," he 

 says, "not as wandering fires, but as works that are eternal in their nature. 

 Every comet has its defined limits."— See Just. Astron. de Lemomiier. To New- 

 ton belongs the honour of having first demonstrated their course by calculation. 

 —Newton's Principia. Euler has equally contributed to throw light upon the 

 movementa of these &ia.rs.—Tlieoria Flanetarum et Cometarum, 1744. 



